Posts Tagged ‘home’

Perl Modules via HTTP Proxy installation, update and install perl CPAN modules behind a Firewall DMZ-ed networks

Friday, May 19th, 2023

If you have to maintain perl script written applications on Linux servers that are sitting behind a very paranoid set-up firewalls
and Local DMZ network, but you still need to maintain the servers and applications versions including perl CPAN (Comprehensive Perl Archive networking) module libraries, you could still do so via another Proxy machine Hub on the Local network, where you either have to manually download all the newest perl versions and CPAN module (libraries) or you can set it up that Proxy machine
to access only a specific Secured internet URLs for perl stuff.

Proxying perl downloads can be done via FTP connects, but as FTP is communicating in plain text and the protocol is known
for not behaving very well behind firewalls, it is a better idea to use for CPAN downloads HTTP or HTTPS protocol.

Normlly Perl is using FTP to download files from the internet. To enable Perl using also HTTP, please install the following RPM:

# yum install perl-libwww-perl

After figure out a CPAN-mirror from, we can start with the configuration from CPAN.

or debian package

# apt install libwww-perl

At the first run from /usr/bin/cpan the initial configuration will be started up which will be done automatically:

[username@linux-host ~]$ cpan

/home/linux-username/.cpan/CPAN/ initialized.

CPAN is the world-wide archive of perl resources. It consists of about
100 sites that all replicate the same contents all around the globe.
Many countries have at least one CPAN site already. The resources
found on CPAN are easily accessible with the module. If you
want to use, you have to configure it properly.

If you do not want to enter a dialog now, you can answer 'no' to this
question and I'll try to autoconfigure. (Note: you can revisit this
dialog anytime later by typing 'o conf init' at the cpan prompt.)

Are you ready for manual configuration? [yes] no


commit: wrote /home/linux-username/.cpan/CPAN/
Terminal does not support AddHistory.

cpan shell — CPAN exploration and modules installation (v1.7602)
ReadLine support available (try 'install Bundle::CPAN')

cpan> q
Terminal does not support GetHistory.
Lockfile removed.
[username@linux-host ~]$

After the initial configuration you have to run /usr/bin/cpan again, to configure the HTTP-proxy and an alternative HTTP-URL for the default FTP URL:

[username@linux-host ~]$ cpan
Terminal does not support AddHistory.

cpan shell — CPAN exploration and modules installation (v1.7602)
ReadLine support available (try 'install Bundle::CPAN')

cpan> o conf http_proxy

cpan> o conf urllist push

cpan> o conf commit
commit: wrote /home/linux-username/.cpan/CPAN/

cpan> q
Terminal does not support GetHistory.
Lockfile removed.
[username@linux-host ~]$

From now CPAN will load it's files from the internet with the HTTP-proxy:

[username@linux-host ~]$ cpan
Terminal does not support AddHistory.

cpan shell — CPAN exploration and modules installation (v1.7602)
ReadLine support available (try 'install Bundle::CPAN')

cpan> i  Example::DB::Oracle
CPAN: Storable loaded ok
CPAN: LWP::UserAgent loaded ok
Fetching with LWP:
Going to read /home/linux-host/.cpan/sources/authors/01mailrc.txt.gz
Fetching with LWP:
Going to read /home/linux-host/.cpan/sources/modules/02packages.details.txt.gz
  Database was generated on Thu, 07 Jan 2010 10:44:22 GMT

  There's a new version (v1.9402) available!
  [Current version is v1.7602]
  You might want to try
    install Bundle::CPAN
    reload cpan
  without quitting the current session. It should be a seamless upgrade
  while we are running…

Fetching with LWP:
Going to read /home/linux-username/.cpan/sources/modules/
Going to write /home/linux-username/.cpan/Metadata
Strange distribution name [Example::DB::Oracle]
Module id = Example::DB::Oracle
    CPAN_VERSION undef
    CPAN_FILE    M/MS/MSERGEANT/DBIx-AnyDBD-2.01.tar.gz
    INST_FILE    (not installed)

cpan> q
Terminal does not support GetHistory.
Lockfile removed.

Now as the new proxy http URL is set on the machine, to upgrade the existing modules non interactively

# perl MCPAN -e upgrade

or do it the old fashioned way via the MCPAN perl shell:

# perl -MCPAN -e shell

Starting with version 2.29 of the cpan shell, a new download mechanism
is the default which exclusively uses as the host to download
from. The configuration variable pushy_https can be used to (de)select
the new mechanism. Please read more about it and make your choice
between the old and the new mechanism by running

    o conf init pushy_https

Once you have done that and stored the config variable this dialog
will disappear.

cpan shell — CPAN exploration and modules installation (v2.29)
Enter 'h' for help.

cpan[1]> upgrade

That's all folks after a while if no errors are spit during the Perl modules update you'll be at the latest versions of CPAN and modules.


Analyze disk space usage in Linux / BSD with du / find and filelight /qdirstat / baobab GUI disk usage analyzers to check what takes up your disk space on Unix like OSes

Friday, April 21st, 2023


If you're a Desktop Linux or BSD UNIX user and your hard disk / external SSD / flash drive etc. space starts to be misteriously disapper due to whatever reaseon such as a crashing applications producing rapidly log error / warning messages leading quickly to filling up the disk or out of a sudden you have some Disk space lost without knowing what kind of data filled up the disk or you're downloading some big sized bittorrent files forgotten in your bittorrent client or complete mirroring a large website and you suddenly get the result of root directory ( / ) getting fully or nearly filled up, then you definitely would want to check out what has disk activity has eaten up your disk space and leaing to OS and Aplication slow responsiveness.

For the Linux regular *nix user finding out what is filling the disk is a trivial task with with find / du -hsc * but as people have different habits to use find and du I'll show you the most common ways I use this two command line tools to identify disk space low issues for the sake of comparison.
Others who have better easier ways to do it are very welcome to share it with me in the comments.

1. Finding large files on hard disk with find Linux command tool

host:~# find /home -type f -printf "%s\t%p\n" | sort -n | tail -10
2100000000    /home/hipo/Downloads/MameUIfx incl. ROMs/MameUIfx incl. ROMs-6.bin
2100000000    /home/hipo/Downloads/MameUIfx incl. ROMs/MameUIfx incl. ROMs-7.bin
2100000000    /home/hipo/Downloads/MameUIfx incl. ROMs/MameUIfx incl. ROMs-8.bin
2100000000    /home/hipo/Downloads/MameUIfx incl. ROMs/MameUIfx incl. ROMs-9.bin
2815424080    /home/hipo/.thunderbird/h3dasfii.default\
2925584895    /home/hipo/Documents/.git/\
4336918067    /home/hipo/Games/Mames_4GB-compilation-best-arcade-games-of-your-14_04_2021.tar.gz
6109003776    /home/hipo/VirtualBox VMs/CentOS/CentOS.vdi
23599251456    /home/hipo/VirtualBox VMs/Windows 7/Windows 7.vdi
33913044992    /home/hipo/VirtualBox VMs/Windows 10/Windows 10.vdi

I use less rarely find on Desktops and more when I have to do some kind of data usage analysis on servers, of course for my Linux home computer and any other Linux desktop machines, or just a small incomprehensive analysis du cmd is much more appropriate to use.

2. Finding large files Megabyte occupying space files sorted in Megabytes and Gigas with du

  • Check main 10 files sorted in megabytes that are hanging in a directory

pcfkreak:~# du -hsc /home/hipo/*|grep 'M\s'|sort -rn|head -n 10
956M    /home/hipo/last_dump1.sql
711M    /home/hipo/hipod
571M    /home/hipo/from-thinkpad_r61
453M    /home/hipo/ultimate-edition-themes
432M    /home/hipo/metasploit-framework
355M    /home/hipo/output-upgrade.txt
333M    /home/hipo/Плот
209M    /home/hipo/Work-New.tar.gz
98M    /home/hipo/DOOM64
90M    /home/hipo/mp3

  • Get 10 top larges files in Gigabytes that are space hungry and eating up your space

pcfkreak:~# du -hsc /home/hipo/*|grep 'G\s'|sort -rn|head -n 10
156G    total
60G    /home/hipo/VirtualBox VMs
37G    /home/hipo/Downloads
18G    /home/hipo/Desktop
11G    /home/hipo/Games
7.4G    /home/hipo/ownCloud
7.1G    /home/hipo/Документи
4.6G    /home/hipo/music
2.9G    /home/hipo/root
2.8G    /home/hipo/Documents

If you want to still work on the console terminal but you don't want to type too much you can use ncdu (ncurses) text tool, install it with

# apt install –yes ncdu

 For the most lazy ones or complete Linux newbies that doesn't want to spend time typing / learing or using text commands or softwares you can also check what has eaten up your full disk space with GUI tools as well.

There are at least 3 tools to use to check in Graphical Interface what has occupied your disk space on Linux / BSD, I'm aware of:

3. Filelight GUI disk usage analysis Linux tool

For those using KDE or preferring a shiny GUI interface that will capture the eye, perhaps filelight would be the option of choice tool to get analysis sum of your directory sturctures and file use on the laptop or desktop *unix OS.

unix-desktop:~# apt-cache show filelight|grep -i description-en -A 7
Description-en: show where your diskspace is being used
 Filelight allows you to understand your disk usage by graphically
 representing your filesystem as a set of concentric, segmented rings.
 It is like a pie-chart, but the segments nest, allowing you to see both
 which directories take up all your space, and which directories
 and files inside those directories are the real culprits.
Description-md5: 397ff9a469e07a772f22460c66b66875

To use it simply go ahead and install it with apt or yum / dnf or whatever Linux package manager your distro uses:

unix-desktop:~# apt-get install –yes filelight


4. GNOME DIsk Usage Analyzer Baobab GUI tool

For those being a GNOME / Mate / Budgie / Cinnamon Graphical interface users baobab shold be the program to use as it uses the famous LibGD library.

unix-desktop:~# apt-cache show baobab|grep -i description-en -A10
Description-en: GNOME disk usage analyzer
 Disk Usage Analyzer is a graphical, menu-driven application to analyse
 disk usage in a GNOME environment. It can easily scan either the whole
 filesystem tree, or a specific user-requested directory branch (local or
 It also auto-detects in real-time any changes made to your home
 directory as far as any mounted/unmounted device. Disk Usage Analyzer
 also provides a full graphical treemap window for each selected folder.
Description-md5: 5f6072b89ebb1dc83433fa7658814dc6



5. Qdirstat graphical application to show where your disk space has gone on Linux

Qdirstat is perhaps well known tool to track disk space issues on Linux desktop hosts, known by the hardcore KDE / LXDE / LXQT / DDE GUI interface / environment lovers and as a KDE tool uses the infamous Qt library. I personally don't like it and don't put it on machines I use because I never use kde and don't want to waste my disk space with additional libraries such as the QT Library which historically was not totally free in terms of licensing and even now is in both free and non free licensing GPL / LGPL and QT Commercial Licensing license.

unix-desktop:~# apt-cache show qdirstat|grep -i description-en -A10
Description-en: Qt-based directory statistics
 QDirStat is a graphical application to show where your disk space has gone and
 to help you to clean it up.
 QDirStat has a number of new features compared to KDirStat. To name a few:
  * Multi-selection in both the tree and the treemap.
  * Unlimited number of user-defined cleanup actions.
  * Properly show errors of cleanup actions (and their output, if desired).
  * File categories (MIME types) and their treemap color are now configurable.
  * Exclude rules for directories are easily configurable.
  * Desktop-agnostic; no longer relies on KDE or any other specific desktop.


That shiny fuzed graphics is actually a repsesantation of all directories the bigger and if one scrolls on the colorful gamma a text with directory and size or file will appear. Though the graphical represantation is really c00l to me it is a bit unreadable, thus I prefer and recommend the other two GUI tools filelight or baobab instead.

6. Finding duplicate files on Linux system with duff command tool

Talking about big unknown left-over files on your hard drives, it is appropriate to mention one tool here that is a console one but very useful to anyone willing to get rid of old duplicate files that are hanging around on the disk. Sometimes such copies are produced while copying large amount of files from place to place or simply by mistake while copying Photo / Video files from your Smart Phone to Linux desktop etc. 

This is where the duff command line utility might be super beneficial for you.

unix-desktop:~# apt-cache show duff|grep -i description-en -A3
Description-en: Duplicate file finder
 Duff is a command-line utility for identifying duplicates in a given set of
 files.  It attempts to be usably fast and uses the SHA family of message
 digests as a part of the comparisons.

Using duff tool is very straight forward to see all the duplicate files hanging in a directory lets say your home folder.

unix-desktop:~#  duff -rP /home/hipo

/home/hipo/music/var/Quake II Soundtrack – Kill Ratio.mp3
/home/hipo/mp3/Quake II Soundtrack – Kill Ratio.mp3
2 files in cluster 44 (7913472 bytes, digest 98f38be49e2ffcbf90927f9357b3e24a81d5a649)
2 files in cluster 45 (2807808 bytes, digest ce9067ce1f132fc096a5044845c7fac73e99c0ed)
/home/hipo/music/var/Quake II Suondtrack – March Of The Stoggs.mp3
/home/hipo/mp3/Quake II Suondtrack – March Of The Stoggs.mp3
2 files in cluster 46 (3506176 bytes, digest efcc401b4ebda9b0b2367aceb8e334c8ba1a357d)
/home/hipo/music/var/Quake II Suondtrack – Quad Machine.mp3
/home/hipo/mp3/Quake II Suondtrack – Quad Machine.mp3
2 files in cluster 47 (7917568 bytes, digest 0905c1d790654016c2ecf2949f78d47a870c3822)
/home/hipo/music/var/Cyberpunk Group – Futureshock!.mp3
/home/hipo/mp3/Cyberpunk Group – Futureshock!.mp3

-r (Recursively search into all specified directories.)

P (Don't follow any symbolic links.  This overrides any previous -H or -L option.  This is the default.  Note that this only applies to directories, as sym‐
             bolic links to files are never followed.)

7. Deleting duplicate files with duff

If you're absolutely sure you know what you're doing and you have a backup in case if something messes up during duplicate teletions, to get rid of lets say any duplicate Picture files found by duff run sommething like:

# duff -e0 -r /home/hipo/Pictures/ | xargs -0 rm

!!! Please note that using duff is for those who absolutely know what they're doing and have their data recent data. Deleting the wrong data by mistake with the tool might put you in the first grade and you'll be the only one to blame  🙂 !!!

Wrap it Up

Filling up the disk with unknown large files is a task to resolve that happens often. For the unlazy on Linux / BSD / Mac OS and other UNIX like OS-es the easiest way is to use find or du with some one liner command. For the lazy Windows addicted Graphical users filelightqdirstat or baobab GUI disk usage analysis tools are there.
If you have a lot of files and many of thems are duplicates you can use duff to check them out and remove all unneded duplicates and save space. 
Hope this article, was helpful for someone.
That's all folks, enjoy your data profilactics, if you know any other good easy command or GUI tools or hints for drive disk space profilactics please share.

iSH, the best free SSH / Telnet client for iOS iPhone, iPad equivallent of MobaXterm and fully functional Alpine Linux emulator

Wednesday, February 8th, 2023


Since few months I've switched my old BLU r1 HD Phone (a great old low budget phone for its price) to a friend's iPhone 10 ( X ) who gifted it for me. Coming from Android world, everyone who has experience with it is a pain in the ass as some of the Apps, which are into Google's play store does not have the same equivalent into Apple's install Package manager tool AppStore. Some of the crucial tools which I was interested as a freshly new migrated user from Android to iPhone was to have a decent SSH / Telnet client and Terminal, with which I can easily connect to my Linux servers both home and work. 

As Android Phone user, to connect and manage my SSH sessions I used most often some of the most popular Connectbot / SSHDroid / JuiceSSH.
On Android I've usually installed all of these tools but most frequently used Connectbot, which quickly become my favourite SSH client for Android over time.

The reasons why I really loved Connectbot and used it on Android OS in short:

  • It is Completely free
  • Ad-free
  • Open-source (too bad not Free software but still step better)
  • Copy and paste text between Applications
  • Customizable interface (i.e. font size, keyboard layout, SSH auth agent, etc.)


I've seen some people used and preferred Termius but never myself really liked this client, as it was including some Advertisements or for don't remember why reason.
Switching to iOS mobile operating system, of course was quite a shock especially the moment I found out the standard loved SSH Remote Client programs are used are not available or have only a paid version. Thus it took me quite a while of a research and googling until I found some decent stuff.


Tried for a time with Termius as well but again, its Ads and lack of some functionality pissed me off, so I've moved on to Shelly.


Shelly is really not a bad tool but has limitation over the SSH sessions you can add and other limitations, which can only be unlocked with an "Upgrade", to its paid version, thus I decided after few weeks of attempts to make it my remote server management mobile tool for iPhone, I've dropped it off as well.

Then I found the Blink Shell App – Blink Shell is a professional, desktop grade terminal for iOS. As overall the tool is really great and is easy to use but again to have it used in its full power you need the paid version and until you pay for it every now and then you got interruption of your shell for some really annoying ads.
Thus even though I used it for a times this few tools with whom basicly you can do basic remote ssh / telnet session operations eventually,  started looking for a better SSH Client Free alternative for iPhone Users.

Then came a friend at home for a dinner my dear friend Milen (Static) and he show me iOS.
The moment I saw this tool I totally loved it, for its simplicity and its resemblance to a classical TTY Physical old Linux console I used back in the days and its ability to resemble easily any improved functionaltiy through simple screen (multiple session management) command tool or tmux.

Wait, what's iSH ? And why it is the Best SSH / Telnet client to manage your servers remotely on iOS Mobiles (iPhone and IPads) ? 

iSH is a project to get a Linux shell environment running locally on your iOS device, using a usermode x86 emulator.

In other wors iSH is Linux emulator with busybox and a package ports for many of the standard Linux tools you get by simple apt-get / yum or if I have to compare you get via the MobaXterm's advanced apt-cyg (Cygwin packages) tool capabilities.

Once iSH is installed it comes with pre-installed apk command line package management tool, with which you can install stuff like openssh-client / screen / tmux / mc (midnight commander) etc. apk, is an apt like command like tool which uses as a basis for installing its packages Alpine Linux repositories.
Alpine Linux is perhaps little known as it is not one of these main stream disributions, such as Fedora or Ubuntu, but for those more concerned about security  Alpine Linux is well known as it is a security-oriented, lightweight Linux distribution based on musl libc and busybox. What makes the Linux even more attractive and perhaps the reason why the iSH developers decided to use it as a basis for their iSH emulator is it being actively developed and its tightened security makes it a good compliment to the quite closed and security focused mobile platform iOS.

iSH is available straight from AppStore , so to use it install it and run it (it is really a great news that iOS does not require iphone to be jailbreak – ed, and it is an ordinary installable software straight from AppStore):
iSH, already comes with some of the standard programs you would expect in a Linux environment such as Vi, wget, zip / unzip, and tar.
However to fit it better for my use over ssh and improve its capabilities, as well as support and use multiple Virtual windows ssh, just like you do on a Linux xterm
run from ish shell: 

# apk add openssh-client
# apk add screen
# apk add vim
# apk add mc




I also like to have a Midnight Commander and VIM Text editor installed out of the box to be able to move around in Ncurses interface through my iPhone.


Note that, just like most GNU / Linux distributions, iOS shell will run a normal bash shell.
From there on to use iSH as my default SSH client and enable my just installed GNU screen some Windowing beauty for readability whence I use the screen with multiple ssh logins to different servers as well make the screen Virtual consoles to have ability for scroll back and scroll up of console text to work, I do set up the following .screenrc inside my /home/iPhoneuser

The .screenrc to setup on the iSH to easify your work with screen is as follows:

# An alternative hardstatus to display a bar at the bottom listing the
# windownames and highlighting the current windowname in blue. (This is only
# enabled if there is no hardstatus setting for your terminal)
hardstatus on
hardstatus alwayslastline
hardstatus string "%{.bW}%-w%{.rW}%n %t%{-}%+w %=%{..G} %H %{..Y} %m/%d %C%a "
# Enable scrolling fix the annoying screen scrolling problem
termcapinfo xterm* ti@:te@
# Scroll up
bindkey -d "^[[5S" eval copy "stuff 5\025"
bindkey -m "^[[5S" stuff 5\025

# Scroll down
bindkey -d "^[[5T" eval copy "stuff 5\004"
bindkey -m "^[[5T" stuff 5\004

# Scroll up more
bindkey -d "^[[25S" eval copy "stuff \025"
bindkey -m "^[[25S" stuff \025

# Scroll down more
bindkey -d "^[[25T" eval copy "stuff \004"
bindkey -m "^[[25T" stuff \004

You can download the same .screenrc file from here straight with wget from the console:

# wget

Run GNU screen manager


 # screen

You will end up with a screen session, to open a new session for Virtual Terminal use virtual keyboard from ISH and Press

CTRL + A + C

To open other Virtual Windows inside screen just press CTRL + A + C as many times as you need it, each session will appear ina small window on the down corner as you can see in screenshot


To move across the Screen unnamed 3 Virtual Windows 0 ash 1 ash and 2 ash use the Virtual keyboard

for next WIndow use key combination:

CTRL + A + N (where + is just to indicate you have to press them once after another and not actually press the + 🙂 )

For Previous Window use:

CTRL + A + P

Or use CTRL + A and type 

:number 3 (where number is the number of window)

The available iSH commands without adding any further packages which are part of the busybox install are as follows:

Available /bin/ directory commands:

arch  ash  base64  bbconfig  busybox  cat  chgrp  chmod  chown  conspy  cp  date  dd  df  dmesg  dnsdomainname  dumpkmap  echo  ed  egrep  false  fatattr  fdflush  fgrep  fsync  getopt  grep  gunzip  gzip  hostname  ionice  iostat  ipcalc  kbd_mode  kill  link  linux32  linux64  ln  login  ls  lzop  makemime  mkdir  mknod  mktemp  more  mount  mountpoint  mpstat  mv  netstat  nice  pidof  ping  ping6  pipe_progress  printenv  ps  pwd  reformime  rev  rm  rmdir  run-parts  sed  setpriv  setserial  sh  sleep  stty  su  sync  tar  touch  true  umount  uname  usleep  watch  zcat  

Available /usr/bin/ commands:    

awk  basename  beep  blkdiscard  bunzip2  bzcat  bzip2  cal  chvt  cksum  clear  cmp  comm  cpio  crontab  cryptpw  cut  dc  deallocvt  diff  dirname  dos2unix  du  dumpleases  eject  env  expand  expr  factor  fallocate  find  flock  fold  free  fuser  getconf  getent  groups  hd  head  hexdump  hostid  iconv  id  install  ipcrm  ipcs  killall  ldd  less  logger  lsof  lsusb  lzcat  lzma  lzopcat  md5sum  mesg  microcom  mkfifo  mkpasswd  nc  nl  nmeter  nohup  nproc  nsenter  nslookup  od  passwd  paste  patch  pgrep  pkill  pmap  printf  pscan  pstree  pwdx  readlink  realpath  renice  reset  resize  scanelf  seq  setkeycodes  setsid  sha1sum  sha256sum  sha3sum  sha512sum  showkey  shred  shuf  smemcap  sort  split  ssl_client  strings  sum  tac  tail  tee  test  time  timeout  top  tr  traceroute  traceroute6  truncate  tty  ttysize  udhcpc6  unexpand  uniq  unix2dos  unlink  unlzma  unlzop  unshare  unxz  unzip  uptime  uudecode  uuencode  vi  vlock  volname  wc  wget  which  whoami  whois  xargs  xxd  xzcat  yes  

If you're a maniac developer you can even use iSH, to do some programs development with vim with Python / Perl or PHP as these are available from the Alpine repositories and installable via a simple apk add packagename for security experts nmap and some security tools are also available but unfortunately not everything is still working as this project is in active development and iOS has some security limitations if OS is not ROOTED 🙂

Hence some of the packages you can install via apk manager will be failing actually.
There is a list of What works and what doesn't still on iSH on the project github wiki check it out here.

There is much more funny stuff you can do with it, and actually my quick research on how people use iSH on their phones lead me to some Videos talking about iOS and Ethical hacking etc, but I'll stop here as I dont have the time to dig deeper to it. 
If you know or have some good use of iSH or some other goody you are using as a hack please share in comments.

Enjoy ! 🙂

How to extend LVM full partition to bigger size on Linux Virtual machine Guest running in VMware vSphere

Tuesday, September 20th, 2022


Lets say you have to resize a partition that is wrongly made by some kind of automation like ansible or puppet,
because the Linux RHEL family OS template was prepared with a /home (or other partition with some very small size)  on VMware Vsphere Hypervisor hosting the Guest linux VM and the partition got quickly out of space.

To resolve the following question comes for the sysadmin

I. How to extend the LVM parititon that run out of space (without rebooting the VM Guest Linux Host)

II. how to add new disk partition space to the vSphere hypervisor OS. 

In below article i'll shortly describe that trivials steps to take to achieve that. Article won't show anything new original but I wrote it,
because I want it to have it logged for myself in case I need to LVM extend the space of my own Virtual machines and 
cause hopefully that might be of help to someone else from the Linux community that has to complete the same task.

I . Extending a LVM parititon that run out of space on a Linux Guest VM
1. Check the current parititon size that you want to extend

[root@linux-hostname home]# df -h /home/
 Filesystem            Size  Used Avail Use% Mounted on
                       4.7G  4.5G     0 100% /home

2. Check the Virtualization platform

[root@vm-hostname ~]# lshw |head -3
    description: Computer
    product: VMware Virtual Platform

3. Check the Operating System Linux OS type and version 

In this specific case this is a bit old Redhat -like CentOS 6.9 Linux

[root@vmware-host ~]# cat /etc/*release*
CentOS release 6.9 (Final)
CentOS release 6.9 (Final)
CentOS release 6.9 (Final)

4. Find out the type of target filesystem is EXT3, EXT4 or XFS etc.?

[root@vm-hostname ~]# grep home /proc/mounts
/dev/mapper/vg00-home /home ext3 rw,relatime,errors=continue,user_xattr,acl,barrier=1,data=ordered 0 0

Filesystem is handled by LVM thus

5. Check the size of the LVM partition we want to exchange

[root@vm-hostname ~]# lvs |grep home
home vg00 -wi-ao—- 5.00g

6. Check whether free space is available space in the volume group ?

[root@vm-hostname ~]# vgdisplay vg00
  — Volume group —
  VG Name               vg00
  System ID
  Format                lvm2
  Metadata Areas        2
  Metadata Sequence No  15
  VG Access             read/write
  VG Status             resizable
  MAX LV                0
  Cur LV                10
  Open LV               10
  Max PV                0
  Cur PV                2
  Act PV                2
  VG Size               128.99 GiB
  PE Size               4.00 MiB
  Total PE              33022
  Alloc PE / Size       30976 / 121.00 GiB
  Free  PE / Size       2046 / 7.99 GiB
  VG UUID               1F89PB-nIP2-7Hgu-zEVR-5H0R-7GdB-Lfj7t4

Extend VMWare space configured for additional hard disk on Hypervisor (if necessery)

In order for to extend the LVM of course you need to have a pre-existing additional hard-drive on VM (sdb,sdc etc. attached )

– If you need to extend on Vmware Vsphere Hypervisor:
Extend additional harddrive by entering the new size and Validate.

If you have previously extended the size of the Virtual Disk from VMWare to make the Linux guest vm find out about the change
you have to rerun rescan for the respective device that was grown on the HV.

7. Rescan on Linux VM host for changes in disk size from Hypervisor

Rescan disk for new size :

[root@vm-hostname ~]# echo 1> /sys/block/sdX/device/rescan

(where sdX is the extended additional harddrive)

8. Resize LVM physical volume

[root@vm-hostname ~]# pvresize /dev/sdX

9. Enlarge Logical Volume size 

[root@vm-hostname ~]# lvextend -L+5G /dev/mapper/vg00-home
     Extending logical volume LogVol00 to 10.77 GiB
     Logical volume LogVol00 successfully resized

10. Enlarge LVM hosted filesystem size

Filesystem is ext3 or ext4 :

[root@vm-hostname ~]# resize2fs /dev/mapper/vg00-home

– If the filesystem is not ext3 / ext4 but XFS you have to use xfs_growfs to let the FS know about the change.

Filesystem is XFS :

[root@vm-hostname ~]# xfs_growfs /dev/mapper/vg00-home

11. Check the additional filespace is already active on the Linux Guest VM

[root@vm-hostname ~]# df -h /home/
 Filesystem            Size  Used Avail Use% Mounted on
                        10G  4.2G  4.9G  48% /home

12. Verify  the extension of filesystem completed without errors

Check of system log:

[root@vm-hostname ~]# grep -i error /var/log/messages

Check if filesystem is writable.

[root@vm-hostname ~]# touch /home/test

[root@vm-hostname ~]# ls -al /home/test
-rw-r—– 1 root root 0 Sep 20 13:39 /home/test
[root@vm-hostname ~]# rm -f /home/test

II.  How to add additional sdb drive to a Linux host from vSPhere HV lets say (sdb)

1.  On VSphere GUI  interface

-> Select New hard drive and click Add

Enter the desired size for the new disk then unpack the disk parameters to choose Thin provision. Validate and Apply the recommendations.


2. On Linux system VM guest host to detect the new added sdb available space

Discover new disk :

[root@vm-hostname ~]# echo "- – -"> /sys/class/scsi_host/host2/scan && echo "- – -"> /sys/class/scsi_host/host1/scan && echo "- – -"> /sys/class/scsi_host/host0/scan

See  if discovered disk is found in /var/log/messages :

Nov 8 17:33:26 bict4004s kernel: scsi 2:0:2:0: Direct-Access VMware Virtual disk 1.0 PQ: 0 ANSI: 2
Nov 8 17:33:26 bict4004s kernel: scsi target2:0:2: Beginning Domain Validation
Nov 8 17:33:26 bict4004s kernel: scsi target2:0:2: Domain Validation skipping write tests
Nov 8 17:33:26 bict4004s kernel: scsi target2:0:2: Ending Domain Validation
Nov 8 17:33:26 bict4004s kernel: scsi target2:0:2: FAST-40 WIDE SCSI 80.0 MB/s ST (25 ns, offset 127)
Nov 8 17:33:26 bict4004s kernel: sd 2:0:2:0: Attached scsi generic sg3 type 0
Nov 8 17:33:26 bict4004s kernel: sd 2:0:2:0: [sdb] 2097152 512-byte logical blocks: (1.07 GB/1.00 GiB)
Nov 8 17:33:26 bict4004s kernel: sd 2:0:2:0: [sdb] Write Protect is off
Nov 8 17:33:26 bict4004s kernel: sd 2:0:2:0: [sdb] Cache data unavailable
Nov 8 17:33:26 bict4004s kernel: sd 2:0:2:0: [sdb] Assuming drive cache: write through
Nov 8 17:33:26 bict4004s kernel: sd 2:0:2:0: [sdb] Attached SCSI disk

3. Create new LVM Physical Volume

[root@vm-hostname ~]# pvcreate /dev/sdb

4. Enlarge LVM Volume Group to the max available size of /dev/sdb

[root@vm-hostname ~]# vgextend vg00 /dev/sdb

Enlarge LVM Logical Volume

[root@vm-hostname ~]# lvextend -L+10G /dev/mapper/vg00-home

5. Enlarge filesystem to max size of just created LVM

If Filesystem is ext3 or ext4 :

[root@vm-hostname ~]# resize2fs /dev/mapper/vg00-home

Again if we work with XFS additionally do:

[root@vm-hostname ~]# xfs_growfs /dev/mapper/vg00-home

6. Checking filesystem extension completed correct

 [root@vm-hostname ~]# df -h /home

7. Check filesystem is writtable and no errors produced in logs

Check of system log:

[root@vm-hostname ~]# grep -i error /var/log/messages

Check if filesystem is writable.

[root@vm-hostname ~]# touch /home/test

How to move transfer binary files encoded with base64 on Linux with Copy Paste of text ASCII encoded string

Monday, October 25th, 2021


If you have to work on servers in a protected environments that are accessed via multiple VPNs, Jump hosts or Web Citrix and you have no mean to copy binary files to your computer or from your computer because you have all kind of FTP / SFTP or whatever Data Copy clients disabled on remote jump host side or CITRIX server and you still are looking for a way to copy files between your PC and the Remote server Side.
Or for example if you have 2 or more servers that are in a special Demilitarized Network Zones ( DMZ ) and the machines does not have SFTP / FTP / WebServer or other kind of copy protocol service that can be used to copy files between the hosts and you still need to copy some files between the 2 or more machines in a slow but still functional way, then you might not know of one old school hackers trick you can employee to complete the copy of files between DMZ-ed Server Host A lets say with IP address ( -> Server Host B ( The way to complete the binary file copy is to Encode the binary on Server Host A and then, use cat  command to display the encoded string and copy whole encoded cat command output  to your (local PC buffer from where you access the remote side via SSH via the CITRIX or Jump host.). Then decode the encoded file with an encoding tool such as base64 or uuencode. In this article, I'll show how this is done with base64 and uuencode. Base64 binary is pretty standard in most Linux / Unix OS-es today on most Linux distributions it is part of the coreutils package.
The main use of base64 encoding to encode non-text Attachment files to Electronic Mail, but for our case it fits perfectly.
Keep in mind, that this hack to copy the binary from Machine A to Machine B of course depends on the Copy / Paste buffer being enabled both on remote Jump host or Citrix from where you reach the servers as well as your own PC laptop from where you access the remote side.


Base64 Encoding and Decoding text strings legend

The file copy process to the highly secured PCI host goes like this:

1. On Server Host A encode with md5sum command

[root@serverA ~]:# md5sum -b /tmp/inputbinfile-to-encode
66c4d7b03ed6df9df5305ae535e40b7d *inputbinfile-to-encode


As you see one good location to encode the file would be /tmp as this is a temporary home or you can use alternatively your HOME dir

but you have to be quite careful to not run out of space if you produce it anywhere 🙂


2. Encode the binary file with base64 encoding

 [root@serverB ~]:# base64 -w0 inputbinfile-to-encode > outputbin-file.base64

The -w0 option is given to disable line wrapping. Line wrapping is perhaps not needed if you will copy paste the data.


Base64 Encoded string chunk with line wrapping

For a complete list of possible accepted arguments check here.

3. Cat the inputbinfile-to-encode just generated to display the text encoded file in your SecureCRT / Putty / SuperPutty etc. remote ssh access client

[root@serverA ~]:# cat /tmp/inputbinfile-to-encode
EAAOAALAEAAHQAcAAYAAAAEAAA ……………………………………………………………… cTD6lC+ViQfUCPn9bs


4. Select the cat-ted string and copy it to your PC Copy / Paste buffer

If the bin file is not few kilobytes, but few megabytes copying the file might be tricky as the string produced from cat command would be really long, so make sure the SSH client you're using is configured to have a large buffer to scroll up enough and be able to select the whole encoded string until the end of the cat command and copy it to Copy / Paste buffer.


5. On Server Host B paste the bas64 encoded binary inside a newly created file

Open with a text editor vim / mc or whatever is available

[root@serverB ~]:# vi inputbinfile-to-encode

Some very paranoid Linux / UNIX systems might not have even a normal text editor like 'vi' if you happen to need to copy files on such one a useful thing is to use a simple cat on the remote side to open a new File Descriptor buffer, like this:

[root@server2 ~]:# cat >> inputbinfile-to-encode <<'EOF'
Paste the string here


6. Decode the encoded binary with base64 cmd again

[root@serverB ~]:# base64 –decode outputbin-file.base64 > inputbinfile-to-encode


7. Set proper file permissions (the same as on Host A)

[root@serverB ~]:#  chmod +x inputbinfile-to-encode


8. Check again the binary file checksum on Host B is identical as on Host A

[root@serverB ~]:# md5sum -b inputbinfile-to-encode
66c4d7b03ed6df9df5305ae535e40b7d *inputbinfile-to-encode

As you can md5sum match on both sides so file should be OK.


9. Encoding and decoding files with uuencode

If you are lucky and you have uuencode installed (sharutils) package is present on remote machine to encode lets say an archived set of binary files in .tar.gz format do:

Prepare the archive of all the files you want to copy with tar on Host A:

[root@Machine1 ~]:#  tar -czvf /bin/whatever /usr/local/bin/htop /usr/local/bin/samhain /etc/hosts archived-binaries-and-configs.tar.gz

[root@Machine1 ~]:# uuencode archived-binaries-and-configs.tar.gz archived-binaries-and-configs.uu

Cat / Copy / paste the encoded content as usual to a file on Host B:

Then on Machine 2 decode:

[root@Machine2 ~]:# uuencode -c < archived-binaries-and-configs.tar.gz.uu



In this short method I've shown you a hack that is used often by script kiddies to copy over files between pwn3d machines, a method which however is very precious and useful for sysadmins like me who has to admin a paranoid secured servers that are placed in a very hard to access environments.

With the same method you can encode or decode not only binary file but also any standard input/output file content. base64 encoding is quite useful stuff to use also in bash scripts or perl where you want to have the script copy file in a plain text format . Datas are encoded and decoded to make the data transmission and storing process easier. You have to keep in mind always that Encoding and Decoding are not similar to encryption and decryption as encr. deprytion gives a special security layers to the encoded that. Encoded data can be easily revealed by decoding, so if you need to copy between the servers very sensitive data like SSL certificates Private RSA / DSA key, this command line utility tool better to be not used for sesitive data copying.



Deny DHCP Address by MAC on Linux

Thursday, October 8th, 2020

Deny DHCP addresses by MAC ignore MAC to not be DHCPD leased on GNU / Linux howto

I have not blogged for a long time due to being on a few weeks vacation and being in home with a small cute baby. However as a hardcore and a bit of dumb System administrator, I have spend some of my vacation and   worked on bringing up the the and the other Websites hosted as a high availvailability ones living on a 2 Webservers running on a Master to Master MySQL Replication backend database, this is oll hosted on  servers, set to run as a round robin DNS hosts on 2 servers one old Lenove ThinkCentre Edge71 as well as a brand new real Lenovo server Lenovo ThinkServer SD350 with 24 CPUs and a 32 GB of RAM
To assure Internet Connectivity is having a good degree of connectivity and ensure websites hosted on both machines is not going to die if one of the 2 pair configured Fiber Optics Internet Providers Bergon.NET has some Issues, I've rented another Internet Provider Line is set bought from the VIVACOM Mobile Fiber Internet provider – that is a 1 Gigabit Fiber Optics Line.
Next to that to guarantee there is no Database, Webserver, MailServer, Memcached and other running services did not hit downtimes due to Electricity power outage, two Powerful Uninterruptable Power Supplies (UPS)  FPS Fortron devices are connected to the servers each of which that could keep the machine and the connected switches and Servers for up to 1 Hour.

The machines are configured to use dhcpd to distributed IP addresses and the Main Node is set to distribute IPs, however as there is a local LAN network with more of a personal Work PCs, Wireless Devices and Testing Computers and few Virtual machines in the Network and the IPs are being distributed in a consequential manner via a ISC DHCP server.

As always to make everything work properly hence, I had again some a bit weird non-standard requirement to make some of the computers within the Network with Static IP addresses and the others to have their IPs received via the DHCP (Dynamic Host Configuration Protocol) and add some filter for some of the Machine MAC Addresses which are configured to have a static IP addresses to prevent the DHCP (daemon) server to automatically reassign IPs to this machines.

After a bit of googling and pondering I've done it and some of the machines, therefore to save others the efforts to look around How to set Certain Computers / Servers Network Card MAC (Interfaces) MAC Addresses  configured on the LAN network to use Static IPs and instruct the DHCP server to ingnore any broadcast IP addresses leases – if they're to be destined to a set of IGNORED MAcs, I came up with this small article.

Here is the DHCP server /etc/dhcpd/dhcpd.conf from my Debian GNU / Linux (Buster) 10.4


option domain-name "pcfreak.lan";
option domain-name-servers,,,;
max-lease-time 891200;
class "black-hole" {
    match substring (hardware, 1, 6);
    ignore booting;
subclass "black-hole" 18:45:91:c3:d9:00;
subclass "black-hole" 70:e2:81:13:44:11;
subclass "black-hole" 70:e2:81:13:44:12;
subclass "black-hole" 00:16:3f:53:5d:11;
subclass "black-hole" 18:45:9b:c6:d9:00;
subclass "black-hole" 16:45:93:c3:d9:09;
subclass "black-hole" 16:45:94:c3:d9:0d;/etc/dhcpd/dhcpd.conf
subclass "black-hole" 60:67:21:3c:20:ec;
subclass "black-hole" 60:67:20:5c:20:ed;
subclass "black-hole" 00:16:3e:0f:48:04;
subclass "black-hole" 00:16:3e:3a:f4:fc;
subclass "black-hole" 50:d4:f5:13:e8:ba;
subclass "black-hole" 50:d4:f5:13:e8:bb;
subnet netmask {
        option routers        ;
        option subnet-mask    ;
host think-server {
        hardware ethernet 70:e2:85:13:44:12;
default-lease-time 691200;
max-lease-time 891200;
log-facility local7;

To spend you copy paste efforts a file with Deny DHCP Address by Mac Linux configuration is here
Of course I have dumped the MAC Addresses to omit a data leaking but I guess the idea behind the MAC ADDR ignore is quite clear

The main configuration doing the trick to ignore a certain MAC ALenovo ThinkServer SD350ddresses that are reachable on the Connected hardware switch on the device is like so:

class "black-hole" {
    match substring (hardware, 1, 6);
    ignore booting;
subclass "black-hole" 18:45:91:c3:d9:00;

The Deny DHCP Address by MAC is described on distribution lists here but it seems the documentation on the topic on how to Deny / IGNORE DHCP Addresses by MAC Address on Linux has been quite obscure and limited online.

As you can see in above config the time via which an IP is freed up and a new IP lease is done from the server is severely maximized as often DHCP servers do use a max-lease-time like 1 hour (3600) seconds:, the reason for increasing the lease time to be to like 10 days time is that the IPs in my network change very rarely so it is a waste of CPU cycles to do a frequent lease.

default-lease-time 691200;
max-lease-time 891200;

As you see to Guarantee resolving works always as expected I have configured – Google Public DNS and OpenDNS IPs

option domain-name-servers,,,;

One hint to make is, after setting up all my desired config in the standard config location /etc/dhcp/dhcpd.conf it is always good idea to test configuration before reloading the running dhcpd process.


root@pcfreak: ~# /usr/sbin/dhcpd -t
Internet Systems Consortium DHCP Server 4.4.1
Copyright 2004-2018 Internet Systems Consortium.
All rights reserved.
For info, please visit
Config file: /etc/dhcp/dhcpd.conf
Database file: /va/home/hipo/infor/lib/dhcp/dhcpd.leases
PID file: /var/run/

That's all folks with this sample config the IPs under subclass "black-hole", which are a local LAN Static IP Addresses will never be offered leasess anymore from the ISC DHCP.
Hope this stuff helps someone, enjoy and in case if you need a colocation of a server or a website hosting for a really cheap price on this new set High Availlability up described machines open an inquiry on


Howto Configure Linux shell Prompt / Setup custom Terminal show Prompt using default shell variables PS1, PS2, PS3, PS4

Tuesday, August 27th, 2019


System Console, Command Operation Console  or Terminal is a Physical device for text (command) input from keyboard, getting the command output and monitoring the status of a shell or programs I/O operations generated traditionally with attached screen. With the development of Computers, physical consoles has become emulated and the input output is translated on the monitor usually via a data transfer  protocol historically mostly over TCP/IP connection to remote IP with telnet or rsh, but due to security limitations Consoles are now accessed over data (encrypted) network protocols with SHA2 / MD5 cryptography algorithm enabled such as over SSH (Secure Shell) network protocol..
The ancestors of physical consoles which in the past were just a Terminal (Monitoring / Monitor device attached to a MainFrame system computer).


What is Physical Console
A classical TTY (TeleTYpewriter) device looked like so and served the purpose of being just a communication and display deivce, whether in reality the actual computing and storage tape devices were in a separate room and communicating to Terminal.

TTYs are still present in  modern UNIX like GNU / Linux distrubions OSes and the BSD berkley 4.4 code based FreeBSD / NetBSD / OpenBSD if you have installed the OS on a physical computer in FreeBSD and Solaris / SunOS there is also tty command. TTY utility in *nix writes the name of the terminal attached to standard input to standard output, in Linux there is a GNU remake of same program part called GNU tty of coreutils package (try man tty) for more.

The physical console is recognizable in Linux as it is indicated with other tree letters pts – (pseudo terminal device) standing for a terminal device which is emulated by an other program (example: xterm, screen, or ssh are such programs). A pts is the slave part of a pts is pseudo there is no separate binary program for it but it is dynamically allocated in memory.
PTS is also called Line consle in Cisco Switches / Router devices, VTY is the physical Serial Console connected on your Cisco device and the network connection emulation to network device is creates with a virtual console session VTL (Virtual Terminal Line). In freebsd the actual /dev/pts* /dev/tty* temporary devices on the OS are slightly different and have naming such as /dev/ttys001.
But the existence of tty and pts emulator is not enough for communicating interrupts to Kernel and UserLand binaries of the Linux / BSD OS, thus to send the commands on top of it is running a System Shell as CSH / TSH / TCSH or BASH which is usually the first program set to run after user logs in over ptty or pseudo tty virtual terminal.



Setting the Bash Prompt in Terminal / Console on GNU / Linux

Bash has system environments to control multiple of variables, which are usually visible with env command, one important variable to change in the past was for example USER / USERNAME which was red by IRC Chat clients  such as BitchX / irssi and could be displayed publicly so if not changed to a separate value, one could have known your Linux login username by simple /whois query to the Nickname in question (if no inetd / xinetd service was running on the Linux box and usually inetd was not running).

Below is my custom set USER / USERNAME to separate

hipo@pcfreak:~$ env|grep USER

There is plenty of variables to  tune email such as MAIL store directory, terminal used TERM, EDITOR etc. but there are some
variables that are not visible with env query as they're not globally available for all users but just for the single user, to show this ones you need to use declare command instead, to get a full list of All Single and System Wide defined variables and functions type declare in the bash shell, for readability, below is last 10 returned results:


hipo@pcfreak:~$ declare | tail -10
    local quoted=${1//\'/\'\\\'\'};
    printf "'%s'" "$quoted"
quote_readline ()
    local quoted;
    _quote_readline_by_ref "$1" ret;
    printf %s "$ret"


PS1 is present there virtually on any modern Linux distribution and is installed through user home's directory $HOME/.bashrc , ~/.profile or .bash_profile or System Wide globally for all existing users in /etc/passwd (password database file) from /etc/bash.bashrc
In Debian / Ubuntu / Mint GNU / Linux this system variable is set in user home's .bashrc but in Fedora / RHEL Linux distro,
PS1 is configured from /home/username/.bash_profile to find out where PS1 is located for ur user:

cd ~
grep -Rli PS1 .bash*

Here is one more example:

hipo@pcfreak:~$ declare|grep -i PS1|head -1
PS1='\[\e]0;\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '

hipo@pcfreak:~$ grep PS1 /etc/bash.bashrc
[ -z “$PS1” ] && return
# but only if not SUDOing and have SUDO_PS1 set; then assume smart user.
if ! [ -n “${SUDO_USER}” -a -n “${SUDO_PS1}” ]; then
  PS1='${debian_chroot:+($debian_chroot)}\u@\h:\w\$ '

Getting current logged in user shell configured PS1 variable can be done with echo:

hipo@pcfreak:~$ echo $PS1
\[\e]0;\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\u@\h:\w\$

So lets observe a little bit the meaning of this obscure line of (code) instructions code which are understood by BASH when being red from PS1 var to do so, I'll give a list of meaning of main understood commands, each of which is defined with \.

The ${debian_chroot} shell variable is defined from /etc/bash.bashrc

Easiest way to change PS1 is to export the string you like with the arguments like so:


root@linux:/home/hipo# export PS1='My-Custom_Server-Name# '
My-Custom_Server-Name# echo $PS1


  •     \a : an ASCII bell character (07)
  •     \d : the date in “Weekday Month Date” format (e.g., “Tue May 26”)
  •     \D{format} : the format is passed to strftime(3) and the result is inserted into the prompt string; an empty format results in a locale-specific time representation. The braces are required
  •     \e : an ASCII escape character (033)
  •     \h : the hostname up to the first ‘.’
  •     \H : the hostname
  •     \j : the number of jobs currently managed by the shell
  •     \l : the basename of the shell's terminal device name
  •     \n : newline
  •     \r : carriage return
  •     \s : the name of the shell, the basename of $0 (the portion following the final slash)
  •     \t : the current time in 24-hour HH:MM:SS format
  •     \T : the current time in 12-hour HH:MM:SS format
  •     \@ : the current time in 12-hour am/pm format
  •     \A : the current time in 24-hour HH:MM format
  •     \u : the username of the current user
  •     \v : the version of bash (e.g., 2.00)
  •     \V : the release of bash, version + patch level (e.g., 2.00.0)
  •     \w : the current working directory, with $HOME abbreviated with a tilde
  •     \W : the basename of the current working directory, with $HOME abbreviated with a tilde
  •     \! : the history number of this command
  •     \# : the command number of this command
  •     \$ : if the effective UID is 0, a #, otherwise a $
  •     \nnn : the character corresponding to the octal number nnn
  •     \\ : a backslash
  •     \[ : begin a sequence of non-printing characters, which could be used to embed a terminal control sequence into the prompt
  •     \] : end a sequence of non-printing characters

The default's PS1 set prompt on Debian Linux is:

echo $PS1
\[\e]0;\u@\h: \w\a\]${debian_chroot:+($debian_chroot)}\u@\h:\w\$

As you can see \u (print username) \h (print hostname)  and \W (basename of current working dir) or \w (print $HOME/current working dir)
are the most essential, the rest are bell character, escape character etc.

A very good way to make your life easier and learn the abbreviations / generate exactly the PS1 PROMPT you want to have is with Easy Bash PS1 Generator Web Utility
with which you can just click over buttons that are capable to produce all of the PS1 codes.

1. How to show current hour:minute:seconds / print full date in Prompt Shell (PS)

Here is an example with setting the Bash Shell prompt  to include also the current time in format hour:minute:seconds (very useful if you're executing commands on a critical servers and you run commands in some kind of virtual terminal like screen or tmux.

root@pcfreak:~# PS1="\n\t \u@\h:\w# "
14:03:51 root@pcfreak:/home#



export PS1='\u@\H \D{%Y-%m-%d %H:%M;%S%z}] \W ] \$ '



Make superuser appear in RED color (adding PS1 prompt custom color for a User)

root@pcfreak:~$  PS1="\\[$(tput setaf 1)\\]\\u@\\h:\\w #\\[$(tput sgr0)\\]"



In above example the Shell Prompt Color changed is changed for administrator (root) to shebang symbol # in red, green, yellow and blue for the sake to show you how it is done, however this example can be adapted for any user on the system. Setting different coloring for users is very handy if you have to administer Mail Server service like Qmail or other Application that consists of multiple small ones of multiple daemons such as qmail + vpopmail + clamd + mysql etc. Under such circumstances, coloring each of the users in different color like in the example for debugging is very useful.

Coloring the PS1 system prompt on Linux to different color has been a standard practice in Linux Server environments running Redhat Enterprise Linux (RHEL) and SuSE Enterprise Linux and some Desktop distributions such as Mint Linux.

To make The Root prompt Red colored only for system super user (root) on any Linux distribution
, add the following to /etc/bashrc, e.g.

vim /etc/bashrc

# If id command returns zero, you've root access.
if [ $(id -u) -eq 0 ];
then # you are root, set red colour prompt
  PS1="\\[$(tput setaf 1)\\]\\u@\\h:\\w #\\[$(tput sgr0)\\]"
else # normal
  PS1="[\\u@\\h:\\w] $"



2. How to make the prompt of a System user appear Green

Add to ~/.bashrc  following line



PS1="\\[$(tput setaf 2)\\]\\u@\\h:\\w #\\[$(tput sgr0)\\]"


3. Print New line, username@hostname, base PTY, shell level, history (number), newline and full working directory $PWD


export PS1='\n[\u@\h \l:$SHLVL:\!]\n$PWD\$ '


4. Showing the numbert of jobs the shell is currently managing.

This is useful if you run and switch with fg / bg (foreground / background) commands
to switch between jobs and forget some old job.


export PS1='\u@\H \D{%Y-%m-%d %H:%M;%S%z}] \W \$]'


Multi Lines Prompt / Make very colorful Shell prompt full of stats info

PS1="\n\[\033[35m\]\$(/bin/date)\n\[\033[32m\]\w\n\[\033[1;31m\]\u@\h: \[\033[1;34m\]\$(/usr/bin/tty | /bin/sed -e ‘s:/dev/::’): \[\033[1;36m\]\$(/bin/ls -1 | /usr/bin/wc -l | /bin/sed ‘s: ::g’) files \[\033[1;33m\]\$(/bin/ls -lah | /bin/grep -m 1 total | /bin/sed ‘s/total //’)b\[\033[0m\] -> \[\033[0m\]"




5. Set color change on command failure

If you have a broken command or the command ended with non zero output with some kind of bad nasty message and you want to make, that more appearing making it red heighlighted, here is how:


PROMPT_COMMAND='PS1="\[\033[0;33m\][\!]\`if [[ \$? = “0” ]]; then echo “\\[\\033[32m\\]”; else echo “\\[\\033[31m\\]”; fi\`[\u.\h: \`if [[ `pwd|wc -c|tr -d ” “` > 18 ]]; then echo “\\W”; else echo “\\w”; fi\`]\$\[\033[0m\] “; echo -ne “\033]0;`hostname -s`:`pwd`\007"'


6. Other beautiful PS1 Color Prompts with statistics


PS1="\n\[\e[32;1m\](\[\e[37;1m\]\u\[\e[32;1m\])-(\[\e[37;1m\]jobs:\j\[\e[32;1m\])-(\[\e[37;1m\]\w\[\e[32;1m\])\n(\[\[\e[37;1m\]! \!\[\e[32;1m\])-> \[\e[0m\]"





7. Add Muliple Colors to Same Shell prompt


function prompt { local BLUE="\[\033[0;34m\]” local DARK_BLUE=”\[\033[1;34m\]” local RED=”\[\033[0;31m\]” local DARK_RED=”\[\033[1;31m\]” local NO_COLOR=”\[\033[0m\]” case $TERM in xterm*|rxvt*) TITLEBAR=’\[\033]0;\u@\h:\w\007\]’ ;; *) TITLEBAR=”” ;; esac PS1=”\u@\h [\t]> ” PS1=”${TITLEBAR}\ $BLUE\u@\h $RED[\t]>$NO_COLOR " PS2='continue-> ' PS4='$0.$LINENO+ ' }


8. Setting / Change Shell background Color



export PS1="\[$(tput bold)$(tput setb 4)$(tput setaf 7)\]\u@\h:\w $ \[$(tput sgr0)\]"


tput Color Capabilities:

  • tput setab [1-7] – Set a background color using ANSI escape
  • tput setb [1-7] – Set a background color
  • tput setaf [1-7] – Set a foreground color using ANSI escape
  • tput setf [1-7] – Set a foreground color

tput Text Mode Capabilities:

  • tput bold – Set bold mode
  • tput dim – turn on half-bright mode
  • tput smul – begin underline mode
  • tput rmul – exit underline mode
  • tput rev – Turn on reverse mode
  • tput smso – Enter standout mode (bold on rxvt)
  • tput rmso – Exit standout mode
  • tput sgr0 – Turn off all attributes

Color Code for tput:

  • 0 – Black
  • 1 – Red
  • 2 – Green
  • 3 – Yellow
  • 4 – Blue
  • 5 – Magenta
  • 6 – Cyan
  • 7 – White


9. Howto Use bash shell function inside PS1 variable

If you administrate Apache or other HTTPD servers or any other server whose processes are forked and do raise drastically at times to keep an eye while actively working on the server.


function httpdcount { ps aux | grep apache2 | grep -v grep | wc -l } export PS1="\u@\h [`httpdcount`]> "

10. PS2, PS3, PS4 little known variables

I'll not get much into detail to PS2, PS3, PS4 but will mention them as perhaps many people are not even aware they exist.
They're rarely used in the daily system administrator's work but useful for Shell scripting purposes of Dev Ops and Shell Scripting Guru Programmers.

  • PS2 – Continuation interactive prompt

A very long unix command can be broken down to multiple line by giving \ at the end of the line. The default interactive prompt for a multi-line command is “> “.  Let us change this default behavior to display “continue->” by using PS2 environment variable as shown below.

hipo@db-host :~$ myisamchk –silent –force –fast –update-state \
> –key_buffer_size=512M –sort_buffer_size=512M \
> –read_buffer_size=4M –write_buffer_size=4M \
> /var/lib/mysql/bugs/*.MYI
[Note: This uses the default “>” for continuation prompt]

  • PS3 – Prompt used by “select” inside shell script (usefulif you write scripts with user prompts)


  • PS4 – Used by “set -x” to prefix tracing output
    The PS4 shell variable defines the prompt that gets displayed.

You can find  example with script demonstrating PS2, PS3, PS4 use via small shell scripts in thegeekstuff's article Take control of PS1, PS2, PS3, PS4 read it here



In this article, I've shortly reviewed on what is a TTY, how it evolved into Pseudo TTY and how it relates to current shells which are the interface communicating with the modern UNIX like Operating systems's userland and kernel.
Also it was reviewed shortly how the current definitions of shell variables could be viewed with declare cmd. Also I went through on how to display the PS1 variable and  on how to modify PS1 and make the prompt different statistics and monitoring parameters straight into the command shell. I've shown some common PS1 strings that report on current date hour, minute, seconds, modify the coloring of the bash prompt shell, show processes count, and some PS1 examples were given that combines beuatiful shell coloring as well as how the Prompt background color can be changed.
Finally was shown how a combination of commands can be executed by exporting to PS1 to update process counf of Apache on every shell prompt iteration.
Other shell goodies are mostly welcome



Howto create Linux Music Audio CD from MP3 files / Create playable WAV format Audio CD Albums from MP3s

Tuesday, July 16th, 2019


Recently my Mother asked me to prepare a Music Audio CD for her from a popular musician accordionist Stefan Georgiev from Dobrudja who has a unique folklore Bulgarian music.

As some of older people who still remember the age of the CD and who had most likely been into the CD burning Copy / Piracy business so popular in the countries of the ex-USSR so popular in the years 1995-2000 audio ,  Old CD Player Devices were not able to play the MP3 file format due to missing codecs (as MP3 was a proprietary compression that can't be installed on every device without paying the patent to the MP3 compression rights holder.

The revolutionary MP3 compression used to be booming standard for transferring Music data due to its high compression which made an ordinary MP3 of 5 minutes of 5MB (10+ times more compression than an ordinary classic WAV Audio the CPU intensiveness of MP3 files that puts on the reading device, requiring the CD Player to have a more powerful CPU.

Hence  due to high licensing cost and requirement for more powerful CPU enabled Audio Player many procuders of Audio Players never introduced MP3 to their devices and MP3 Neve become a standard for the Audio CD that was the standard for music listening inside almost every car out there.

Nowdays it is very rare need to create a Audio CD as audio CDs seems to be almost dead (As I heard from a Richard Stallman lecture In USA nowadays there is only 1 shop in the country where you can still buy CD or DVD drives) and only in third world as Africa Audio CDs perhaps are still in circulation.

Nomatter that as we have an old Stereo CD player on my village and perhaps many others, still have some old retired CD reading devices being able to burn out a CD is a useful thing.

Thus to make mother happy and as a learning excercise, I decided to prepare the CD for her on my Linux notebook.
Here I'll shortly describe the takes I took to make it happen which hopefully will be useful for other people that need to Convert and burn Audio CD from MP3 Album.


1. First I downloaded the Album in Mp3 format from Torrent tracker

My homeland Bulgaria and specific birth place place the city of Dobrich has been famous its folklore:  Galina Durmushlijska and Stefan Georgiev are just 2 of the many names along with Оркестър Кристал (Orchestra Crystal) and the multitude of gifted singers. My mother has a santiment for Stefan Georgiev, as she listened to this gifted accordinist on her Uncle's marriage.

Thus In my case this was (Стефан Георгиев Хора и ръченици от Добруджа) the album full song list here If you're interested to listen the Album and Enjoy unique Folklore from Dobrudja (Dobrich) my home city, Stefan Georgiev's album Hora and Rachenica Dances is available here


I've downloaded them from Bulgarian famous torrent tracker in MP3 format.
Of course you need to have a CD / DVD readed and write device on the PC which nowdays is not present on most modern notebooks and PCs but as a last resort you can buy some cheap External Optical CD / DVD drive for 25 to 30$ from Amazon / Ebay etc.


2. You will need to install a couple of programs on Linux host (if you don't have it already)

To be able to convert from command line from MP3 to WAV you will need as minimum ffmpeg and normalize-audio packages as well as some kind of command line burning tool like cdrskin  wodim which is
the fork of old good known cdrecord, so in case if you you're wondering what happened with it just
use instead wodim.

Below is a good list of tools (assuming you have enough HDD space) to install:


root@jeremiah:/ # apt-get install –yes dvd+rw-tools cdw cdrdao audiotools growisofs cdlabelgen dvd+rw-tools k3b brasero wodim ffmpeg lame normalize-audio libavcodec58


Note that some of above packages I've installed just for other Write / Read operations for DVD drives and you might not need that but it is good to have it as some day in future you will perhaps need to write out a DVD or something.
Also the k3b here is specific to KDE and if you're a GNOME user you could use Native GNOME Desktop app such brasero or if you're in a more minimalistic Linux desktop due to hardware contrains use XFCE's native xfburn program.

If you're a console / terminal geek like me you will definitely enjoy to use cdw

root@jeremiah:/ # apt-cache show cdw|grep -i description -A 1
Description-en: Tool for burning CD's – console version
 Ncurses-based frontend for wodim and genisoimage. It can handle audio and

Description-md5: 77dacb1e6c00dada63762b78b9a605d5


3. Selecting preferred CD / DVD / BD program to use to write out the CD from Linux console

cdw uses wodim (which is a successor of good old known console cdrecord command most of use used on Linux in the past to burn out new Redhat / Debian / different Linux OS distro versions for upgrade purposes on Desktop and Server machines.

To check whether your CD / DVD drive is detected and ready to burn on your old PC issue:


root@jeremiah:/# wodim -checkdrive
Device was not specified. Trying to find an appropriate drive…
Detected CD-R drive: /dev/cdrw
Using /dev/cdrom of unknown capabilities
Device type    : Removable CD-ROM
Version        : 5
Response Format: 2
Capabilities   :
Vendor_info    : 'HL-DT-ST'
Identification : 'DVDRAM GT50N    '
Revision       : 'LT20'
Device seems to be: Generic mmc2 DVD-R/DVD-RW.
Using generic SCSI-3/mmc   CD-R/CD-RW driver (mmc_cdr).
Supported modes: TAO PACKET SAO SAO/R96P SAO/R96R RAW/R16 RAW/R96P RAW/R96R

You can also use xorriso (whose added value compared to other console burn cd tools is is not using external program for ISO9660 formatting neither it use an external or an external burn program for CD, DVD or BD (Blue Ray) drive but it has its own libraries incorporated from libs.

Below output is from my Thinkpad T420 notebook. If the old computer CD drive is there and still functional in most cases you should not get issues to detect it.

cdw ncurses text based CD burner tool's interface is super intuitive as you can see from below screenshot:


CDW has many advanced abilities such as “blanking” a disk or ripping an audio CD on a selected folder. To overcome the possible problem of CDW not automatically detecting the disk you have inserted you can go to the “Configuration” menu, press F5 to enter the Hardware options and then on the first entry press enter and choose your device (by pressing enter again). Save the setting with F9.

4. Convert MP3 / MP4 Files or whatever format to .WAV to be ready to burn to CD

Collect all the files you want to have collected from the CD album in .MP3 a certain directory and use a small one liner loop to convert files to WAV with ffmpeg:

cd /disk/Music/Mp3s/Singer-Album-directory-with-MP3/

for i in $( ls *.mp3); do ffmpeg -i $i $i.wav; done

If you don't have ffmpeg installed and have mpg123 you can also do the Mp3 to WAV conversion with mpg123 cmd like so:


for i in $( ls ); do mpg123 -w $i.wav $i.mp3; done

Another alternative for conversion is to use good old lame (used to create Mp3 audio files but abling to also) decode
mp3 to wav.


lame –decode somefile.mp3 somefile.wav

In the past there was a burn command tool that was able to easily convert MP3s to WAV but in up2date Linux modern releases it is no longer available most likely due to licensing issues, for those on older Debian Linux 7 / 8 / 9 / Ubuntu 8 to 12.XX / old Fedoras etc. if you have the command you can install burn and use it (and not bother with shell loops):

apt-get install burn


yum install burn

Once you have it to convert


$ burn -A -a *.mp3


5. Fix file naming to remove empty spaces such as " " and substitute to underscores as some Old CD Players are
unable to understand spaces in file naming with another short loop.


for f in *; do mv "$f" `echo $f | tr ' ' '_'`; done


6. Normalize audio produced .WAV files (set the music volume to a certain level)

In case if wondering why normalize audio is needed here is short extract from normalize-audio man page command description to shed some light.

"normalize-audio  is  used  to  adjust  the volume of WAV or MP3 audio files to a standard volume level.  This is useful for things like creating mp3 mixes, where different recording levels on different albums can cause the volume to  vary  greatly from song to song."

cd /disk/Music/Mp3s/Singer-Album-directory-with-MP3/

normalize-audio -m *.wav


7. Burn the produced normalized Audio WAV files to the the CD


wodim -v -fix -eject dev='/dev/sr0' -audio -pad *.wav

Alternatively you can conver all your MP3 files to .WAV with anything be it audacity
or another program or even use 
GNOME's CDBurn tool brasero (if gnome user) or KDE's CDBurn which in my opinion is
the best CD / DVD burning application for Linux K3B.

Burning Audio CD with K3b is up to few clicks and super easy and even k3b is going to handle the MP3 to WAV file Conversion itself. To burn audio with K3B just run it and click over 'New Audio CD Project'.


For those who want to learn a bit more on CD / DVD / Blue-Ray burning on GNU / Linux good readings are:
Linux CD Burning Mini Howto, is Linux's CD Writing Howto on ibiblio (though a bit obsolete) or Debian's official documentation on BurnCD.

8. What we learned here

Though the accent of this tutorial was how to Create Audio Music CD from MP3 on GNU / Linux, the same commands are available in most FreeBSD / NetBSD / OpenBSD ports tree so you can use the same method to build prepare Audio Music CD on *BSDs.

In this article, we went through few basic ways on how to prepare WAV files from MP3 normalize the new created WAV files on Linux, to prepare files for creation of Audio Music CD for the old mom or grandma's player or even just for fun to rewind some memories. For GUI users this is easily done with  k3b,  brasero or xfburn.

I've pointed you to cdw a super useful text ncurses tool that makes CD Burninng from plain text console (on servers) without a Xorg / WayLand  GUI installed super easy. It was shortly reviewed what has changed over the last few years and why and why cdrecord was substituted for wodim. A few examples were given on how to handle conversion through bash shell loops and you were pointed to some extra reading resources to learn a bit more on the topic.
There are plenty of custom scripts around for doing the same CD Burn / Covnersion tasks, so pointing me to any external / Shell / Perl scripts is mostly welcome.

Hope this learned you something new, Enjoy ! 🙂

Virtualbox Shared folder set up on Linux between Host and Guest OS – Set up Virtualbox shared folder to Copy files from PC Host to Guest

Wednesday, September 12th, 2018


How to set-up Virtualbox shared folder to Copy files from PC Host  and Guest Virtualized OS?

Running VirtualBox Host is an easy thing to set-up across all Operating Systems.  Once you have it sooner or later you will need to copy files from the VM Host OS (that in my case is GNU / Linux) to the virtualized Guest operating system (again in my case that's again another Linux ISO running indide the Virtual Machine).

Below are steps to follow To use Virtualbox Shared Folder functionality to copy files between VBox and your Desktop / server Linux install.

1. Install Virtualbox Guest Additions CD Image ISO

I've explained how to add the Guest Additions CD image thoroughfully in my previous article Howto enable Copy / Paste Virtualbox betwen Linux guest and Host OS
Anyways I'll repeat myself below for sake of clarity:

To do so use Oracle VBox menus (on the booted virtualized OS VBox window):


Devices -> Insert Guest additions CD Image


Mount the ISO inside the Linux Virtual Machine:

root@debian:~# mount /media/cdrom1/

If the mount fails and there are no files inside the mount point it might be because the virtualbox-dkms and virtualbox-guest-dkms packages might be missing on the Host OS.

To install them (on Debian GNU / Linux) assuming that you're using virtualbox default distro packages /etc/apt/sources.list :

apt-get install –yes -qq virtualbox-dkms virtualbox-guest-dkms

and run:


root@debian:/media/cdrom1# cd /media/cdrom1; sh

2. Create directory for Shared Folder that will be used to access Host / OS files from the Guest Virtualized OS

root@debian:~# mkdir /mnt/shared_folder


3. Map from VBox program interface Shared folder settings and Mount /mnt/shared_folder location



Devices -> Shared Folder -> Shared Folder settings -> Transient Folders (click blue folder add small button right)


From Transient Folders add whatever directory you want to be shared from your local notebook / PC to the VM.

virtualbox-devices-Shared-Folder-Add-Shared-Folder-add-share-linux-screenshotDepending on whether you would like to mount the shared folder only for reading files (choose Read Only) to make it a permanent shared folder (and not just for the one session of current running Virtual Machine until its killed use Make Permanent) or check Auto-Mount tick if you want the shared_folder mapping to be mounted on every VM boot.

Once the shared_folder directory location is set-up from GUI menu click OK and in order for the settings to take effect, you'll need to restart the VM Guest with Linux (use halt command from terminal) or Power Off the Machine via the VBox menus.

To mount use command like:

mount -t vboxsf name_of_folder_linked_from_vbox  /mnt/name_folder_guest_os/


In my case I wanted to share home folder /home so the command I used is:

root@debian:~# mount -t vboxsf  shared_folder /mnt/shared_folder

If everything is fine your Host OS file content from /home will be visible (for read and write if you Mapped it so) 
under /mnt/shared_folder …

And as Turtles Ninja used to heavily say Cowabunga !!! 🙂
You have it mounted and ready for file share between Desktop -> Virtualized OS.


Bear in mind that above mount command has to run as root (superuser) to succeed.

You now could copy files from your Host OS (running the Virtual Machine) and the Guest OS (Virtualized OS) using /mnt/shared_folder mount point without problems.

The example is if you want to share files between VirtualBox installed Linux and the Guest (Desktop / server) OS, however at many cases mounting your Host OS directory for root users might be not very practical but, instead you might prefer to do the mount for specific non admin user, for example I prefer to do the shared folder mount with my pointed non-root username hipo.

Here is how to do above VM shared_folder mount for non-root user:

First you need to know the exact UID / GID (User ID / Group ID) of user, you can get that with id command:


hipo@linux:~$  id
uid=1000(hipo) gid=1000(hipo) groups=1000(hipo),24(cdrom),25(floppy),29(audio),30(dip),44(video),46(plugdev),108(netdev),114(bluetooth),115(lpadmin),119(scanner)


As you see UID / GID in my case are 1000 / 1000

hipo@linux:~$ sudo mount -t vboxsf -o rw,uid=1000,gid=1000 shared_folder /mnt/shared_folder



4. Mounting configured shared_folder to automatically mount into the Guest OS Linux on every boot

a) Configuring shared_folder auto-mount using /etc/rc.local

If you need the shared_folder to automatically mount next-time you boot the virtual machine quickest way is to add the mount command to /etc/rc.local (on Debian 8 and Debian 9 and newer Ubuntu Linuxes rc.local is missing by default to enable it to work like it worked before read follow my previous article ).

b) Configuring auto-mount for shared_folder through /etc/fstab

The more professional way to auto-mount on emulated OS VM boot time,  you could add the vboxsf mount definitions to /etc/fstab with your favourite text-editor mcedit, nano, joe etc. … (for me that's vim).

Syntax of /etc/fstab is as follows:

<Device> <Mount Point> <Type> <Options> <Dump> <Pass>

root@linux:~# vim /etc/fstab


shared_folder /mnt/shared_folder                                vboxsf rw,uid=1000,gid=1000 0 0

Note that you will want to change 1000 / 1000, id / gid with the ones of the non-admin user you would like to add to mount it for.

A quick way to add it to /etc/fstab with a shell one-liner is with command

root@linux:~# echo 'shared_folder /mnt/shared_folder                                vboxsf rw,uid=1000,gid=1000 0  0' >> /etc/fstab

An alternative way to add a user to have permissions for vboxsf file system (without specifying the long -o uid=1000,gid=1000 options is to simply add the username in question to group vboxsf like so:

c) Adding non super user username to vboxsf group

root@linux:~# usermod -G vboxsf hipo
root@linux:~# grep -i vboxsf /etc/group


hipo@linux:~$ sudo mount -t vboxsf  shared_folder /mnt/shared_folder


without the extra arguments and the options to pass to /etc/fstab (for eventual requirement to auto mount the shared_folder) would be more simple e.g.:


echo 'shared_folder /mnt/shared_folder                                vboxsf ' >> /etc/fstab


One note to make here is if the uesr is added to vboxsf the line for /etc/fstab to auto mount to mount for root user and non-root will be identical.

Then you can get the /etc/fstab auto-mount configured tested by running:

c) Checking auto-mount is working

hipo@linux:~# mount -a
hipo@linux:~# mount |grep -i vboxsf
shared_folder on /mnt/shared_folder type vboxsf (rw,nodev,relatime)

5. What if you end up with mounting failed errors ? – What might be causing the mounting failed Protocol error (a few things to check to solve)

In case of troubles with the mount you might get an error like:

hipo@linux:~# mount -t vboxsf  share_folder /mnt/shared_folder

/sbin/mount.vboxsf: mounting failed with the error: Protocol error

This error might be caused because of Insert Guest Additions CD Image might be not properly enabled and installed using the ISO provided shell script.
Other common reason you might get this error if you have mistyped the Folder name: given in Shared Folders -> Folder Path -> Add Share for example I have given shared_folder as a Map name but as you can see in above mount -t vboxsf, I've mistyped share_folder instead of the correct one shared_folder inserted.
In some VBox releases this error was caused by bugs in the Virtual Machine.


One useful tip is to be able to check whether a Virtualbox Virtual Machine has a configured shared_folder (if you're logging to manage the machine on remote server – nomatter whether you have logged in with VNC / Teamviewer / Citrix etc. or via SSH session.

To do so use VBoxControl as of time of writting usually located on most distributions under (/usr/bin/VBoxControl)


hipo@linux:~# VBoxControl sharedfolder list -automount
Oracle VM VirtualBox Guest Additions Command Line Management Interface Version 5.2.18
(C) 2008-2018 Oracle Corporation
All rights reserved.


Auto-mounted Shared Folder mappings (0):

No Shared Folders available.

You can use VBoxControl command to get set and list a number of settings on the VBox VM, here is an useful example with it where you get information about numerous VBox info values:


root@linux:~# VBoxControl guestproperty enumerate
Oracle VM VirtualBox Guest Additions Command Line Management Interface Version 5.2.18
(C) 2008-2018 Oracle Corporation
All rights reserved.


Name: /VirtualBox/GuestInfo/OS/Product, value: Linux, timestamp: 1536681633430852000, flags: <NULL>
Name: /VirtualBox/GuestInfo/Net/0/V4/IP, value:, timestamp: 1536681633438717000, flags: <NULL>
Name: /VirtualBox/HostInfo/GUI/LanguageID, value: en_US, timestamp: 1536697521395621000, flags: RDONLYGUEST
Name: /VirtualBox/GuestInfo/Net/0/MAC, value: 08002762FA1C, timestamp: 1536681633442120000, flags: <NULL>
Name: /VirtualBox/GuestInfo/OS/ServicePack, value: <NULL>, timestamp: 1536681633431259000, flags: <NULL>
Name: /VirtualBox/HostInfo/VBoxVerExt, value: 5.2.18, timestamp: 1536681619002646000, flags: TRANSIENT, RDONLYGUEST
Name: /VirtualBox/GuestInfo/Net/0/V4/Netmask, value:, timestamp: 1536681633440157000, flags: <NULL>
Name: /VirtualBox/GuestInfo/OS/Version, value: #1 SMP Debian 4.9.110-3+deb9u2 (2018-08-13), timestamp: 1536681633431125000, flags: <NULL>
Name: /VirtualBox/GuestAdd/VersionExt, value: 5.2.18, timestamp: 1536681633431582000, flags: <NULL>
Name: /VirtualBox/GuestAdd/Revision, value: 124319, timestamp: 1536681633432515000, flags: <NULL>
Name: /VirtualBox/HostGuest/SysprepExec, value: <NULL>, timestamp: 1536681619002355000, flags: TRANSIENT, RDONLYGUEST
Name: /VirtualBox/GuestInfo/OS/LoggedInUsers, value: 1, timestamp: 1536681673447293000, flags: TRANSIENT, TRANSRESET
Name: /VirtualBox/GuestInfo/Net/0/Status, value: Up, timestamp: 1536681633443911000, flags: <NULL>
Name: /VirtualBox/GuestInfo/Net/0/Name, value: enp0s3, timestamp: 1536681633445302000, flags: <NULL>
Name: /VirtualBox/HostGuest/SysprepArgs, value: <NULL>, timestamp: 1536681619002387000, flags: TRANSIENT, RDONLYGUEST
Name: /VirtualBox/GuestAdd/Version, value: 5.2.18, timestamp: 1536681633431419000, flags: <NULL>
Name: /VirtualBox/HostInfo/VBoxRev, value: 124319, timestamp: 1536681619002668000, flags: TRANSIENT, RDONLYGUEST
Name: /VirtualBox/GuestInfo/Net/0/V4/Broadcast, value:, timestamp: 1536681633439531000, flags: <NULL>
Name: /VirtualBox/HostInfo/VBoxVer, value: 5.2.18, timestamp: 1536681619002613000, flags: TRANSIENT, RDONLYGUEST
Name: /VirtualBox/GuestInfo/OS/LoggedInUsersList, value: hipo, timestamp: 1536681673446498000, flags: TRANSIENT, TRANSRESET
Name: /VirtualBox/GuestInfo/Net/Count, value: 1, timestamp: 1536698949773993000, flags: <NULL>
Name: /VirtualBox/GuestInfo/OS/Release, value: 4.9.0-7-amd64, timestamp: 1536681633431001000, flags: <NULL>
Name: /VirtualBox/GuestInfo/OS/NoLoggedInUsers, value: false, timestamp: 1536681673447965000, flags: TRANSIENT, TRANSRESET
Name: /VirtualBox/GuestAdd/HostVerLastChecked, value: 5.2.18, timestamp: 1536681702832389000, flags: <NULL>

Hope you enjoyed ! Have phun! 🙂

Why don’t you use Window Maker GNU Step to improve your computer interaction performance

Monday, October 30th, 2017


If you're pissed off too already of GNOME 3 Unity / GNOME 3 Flashback and KDE Plasma  as I am you perhaps are looking for something more light weigth but you're not okay with default Debian Cinnanom GUI environment or you don't feel confortable for system administration jobs and programming with XFCE then perhaps you would like to give a try to something more old school but build with good design in Mind.

Those who are fans of the evil genius Steve Jobs (as Richard Stallman use to call him), definitely Remember NeXT company and the revolutionary Graphic Environment they tried to develop NeXT Step then you'll be happy to hear about GNUStep  which historically was called AfterStep and is a Free Software remake of NextStep graphical environment for Free and Open Source operating systems (FOSS) such as GNU / Linux and FreeBSD / OpenBSD / NetBSD etc.


Amanda the Panda is the mascot of Window Maker. She was designed by Agnieszka Czajkowska.

The good thing about Window Maker and the complete bunch of desktop environment GNUStep is it much lighter and less complex than the more and more becoming bloated modern Free Software graphical environments, it definitely easifies the way the user interacts with basic browsing with Firefox / Opera, terminal code writting or command system administration and basic chat functionalities such as with Gajim or Pidgin and basic email writting operatins be it with some text email client such as Mutt or with Thunderbird. Its great also to reduce the overall load the Operating System puts on your brain so you can have more time to invest in more useful stuff like programming.


After all simplicity in Operating System is a key for an increased productivity with your computer.
Besides that stability of Window Maker is much better when compared to GNOME and GNOME 2 fork MATE graphical environment which nowadays in my opinion is becoming even more buggy than it used to be some years ago.

Below is how Window Makers site describes Window Maker:

"Window Maker is an X11 window manager originally designed to provide integration support for the GNUstep Desktop Environment. In every way possible, it reproduces the elegant look and feel of the NEXTSTEP user interface. It is fast, feature rich, easy to configure, and easy to use. It is also free software, with contributions being made by programmers from around the world.

Window Maker has a stable user interface since many years and comes with a powerful GUI configuration editor called WPrefs, which removes the need to edit text-based config files by hand. It supports running dockapps which make everyday tasks such as monitoring system performance and battery usage, mounting devices or connecting to the internet very easy. Please see the features section for more specifics on what Window Maker can do, and how it compares with other popular window managers."

Window Maker is bundled with a number of useful applications which gives ability to put Dock applets easily for easily intearcive desktop update of current Weather Report, Monitoring Network Traffic, TV Player (video4linux), laptop battery info dock, CD player and Volume control management app, text editor, pdf viewer, integrated Mail application, Calculator, RSS Reader, GNUStep games and much useful things to customize from the desktop resembling many of the basic features any other graphical environment such as GNOME / KDE Provides.

The User Interface (UI) of Window Maker is highly configurable with an integrated WMaker tool called



All generated settings from WPrefs (Window Maker Prefernces) GUI tool are to be stored in a plaintext file:


All Wmaker configurations are stored inside ~/GNUstep/ (Your user home GNUStep), so if you're to become its user sooner or later you will have to get acquired to it.

Wmaker is very minimalist and the performance is killing so Window Maker is perhaps the number one choice Graphical Environment to use on Old Computers with Linux and BSD.

Below is a full list of all packages installed on my Debian GNU / Linux that provides WMaker / GNUStep great functionalities:

root@jericho:/home/hipo# dpkg -l |grep -i wmaker; dpkg -l |grep -i gnustep
ii  wmaker                                        0.95.8-2                             amd64        NeXTSTEP-like window manager for X
ii  wmaker-common                                 0.95.8-2                             all          Window Maker – Architecture independent files
ii  wmbattery                                     2.50-1+b1                            amd64        display laptop battery info, dockable in WindowMaker
ii  wmcdplay                                      1.1-2+b1                             amd64        CD player based on ascd designed for WindowMaker
ii  wmifs                                         1.8-1                                amd64        WindowMaker dock app for monitoring network traffic
ii  wmnut                                         0.66-1                               amd64        WindowMaker dock app that displays UPS statistics from NUT's upsd
ii  wmpuzzle                                      0.5.2-2+b1                           amd64        WindowMaker dock app 4×4 puzzle
ii  wmrack                                        1.4-5+b1                             amd64        Combined CD Player + Mixer designed for WindowMaker
ii  wmtv                                          0.6.6-1                              amd64        Dockable video4linux TV player for WindowMaker
ii  wmweather                                     2.4.6-2+b1                           amd64        WindowMaker dockapp that shows your current weather
ii  wmweather+                                    2.15-1.1+b2                          amd64        WindowMaker dock app that shows your current weather
ii                            0.4.8-2+b2                           amd64        Personal Address Manager for GNUstep
ii                                    0.42.2-1+b7                          amd64        Calendar manager for GNUstep
ii                                   0.3~rc1-3                            amd64        Character map for GNUstep
ii                            0.3~rc1-3                            all          Character map for GNUstep (arch-independent files)
ii                                 1.0.0-1+b4                           amd64        Music player for GNUstep
ii                          0+20080616+dfsg-2+b6                 amd64        Dict client for GNUstep
ii                                  1.1.1a-7.1+b1                        amd64        Scientific calculator for GNUstep
ii                                   1.2.2-1.1                            amd64        Mail client for GNUstep
ii                            1.2.2-1.1                            all          Mail client for GNUstep (common files)
ii  gnustep                                       7.8                                  all          User applications for the GNUstep Environment
ii  gnustep-back-common                           0.25.0-2                             amd64        GNUstep GUI Backend – common files
ii  gnustep-back0.25                              0.25.0-2                             all          GNUstep GUI Backend
ii  gnustep-back0.25-cairo                        0.25.0-2                             amd64        GNUstep GUI Backend (cairo)
ii  gnustep-base-common                           1.24.9-3.1                           all          GNUstep Base library – common files
ii  gnustep-base-doc                              1.24.9-3.1                           all          Documentation for the GNUstep Base Library
ii  gnustep-base-runtime                          1.24.9-3.1                           amd64        GNUstep Base library – daemons and tools
ii  gnustep-common                                2.7.0-1                              amd64        Common files for the core GNUstep environment
ii  gnustep-core-devel                            7.8                                  all          GNUstep Development Environment — core libraries
ii  gnustep-core-doc                              7.8                                  all          GNUstep Development Environment — core documentation
ii  gnustep-devel                                 7.8                                  all          GNUstep Development Environment — development tools
ii  gnustep-games                                 7.8                                  all          GNUstep games
ii  gnustep-gui-common                            0.25.0-4                             all          GNUstep GUI Library – common files
ii  gnustep-gui-doc                               0.25.0-4                             all          Documentation for the GNUstep GUI Library
ii  gnustep-gui-runtime                           0.25.0-4+b1                          amd64        GNUstep GUI Library – runtime files
ii  gnustep-icons                                 1.0-5                                all          Several free icons for use with GNUstep and others
ii  gnustep-make                                  2.7.0-1                              all          GNUstep build system
ii  gnustep-make-doc                              2.7.0-1                              all          Documentation for GNUstep Make
ii                                    1.2.9-2+b2                           amd64        Extended TicTacToe game for GNUstep
ii                                      1.2.23-1                             amd64        Visual Interface Builder for GNUstep
ii                                  1.10-4+b2                            amd64        Collection of grid-based board games for GNUstep
ii                                       1.0-1+b2                             amd64        RSS reader for GNUstep
ii  gworkspace-common                             0.9.3-1                              all          GNUstep Workspace Manager – common files
ii                                0.9.3-1+b2                           amd64        GNUstep Workspace Manager
ii                                0.3-8+b3                             amd64        Online help viewer for GNUstep programs
ii  libaddresses0                                 0.4.8-2+b2                           amd64        Database API backend framework for GNUstep (library files)
ii  libaddressview0                               0.4.8-2+b2                           amd64        Address display/edit framework for GNUstep (library files)
ii  libgnustep-base-dev                           1.24.9-3.1                           amd64        GNUstep Base header files and development libraries
ii  libgnustep-base1.24                           1.24.9-3.1                           amd64        GNUstep Base library
ii  libgnustep-gui-dev                            0.25.0-4+b1                          amd64        GNUstep GUI header files and static libraries
ii  libgnustep-gui0.25                            0.25.0-4+b1                          amd64        GNUstep GUI Library
ii  libpantomime1.2                               1.2.2+dfsg1-1                        amd64        GNUstep framework for mail handling (runtime library)
ii  libpopplerkit0                                0.0.20051227svn-7.1+b9               amd64        GNUstep framework for rendering PDF content (library files)
ii  libpreferencepanes1                           1.2.0-2+b2                           amd64        GNUstep preferences library – runtime library
ii  librenaissance0                               0.9.0-4+b6                           amd64        GNUstep GUI Framework – library files
ii  librenaissance0-dev                           0.9.0-4+b6                           amd64        GNUstep GUI Framework – development files
ii  librsskit0d                                   0.4-1                                amd64        GNUstep RSS framework (runtime library)
ii  mknfonts.tool                                 0.5-11+b5                            amd64        Create nfont packages for GNUstep
ii                                     1.3.0-1                              amd64        Image filtering and manipulation using GNUstep
ii                             0.6.2-1                              amd64        IDE for GNUstep Development
ii  renaissance-doc                               0.9.0-4                              all          GNUstep GUI Framework – documentation
ii                         1.2.0-2+b2                           amd64        GNUstep preferences application
ii                                                    amd64        Terminal Emulator for GNUstep
ii                                  4.0+20061029-3.5+b1                  amd64        Text editor for GNUstep
ii                                   1:0.2dfsg1-5+b2                      amd64        Portable Document Format (PDF) viewer for GNUstep
ii                                    1.5-1+b2                             amd64        Archive manager for GNUstep

Well yes it is true Window Maker is not a spoon for every mouth, those who want to have more confortable desktop environment better look out at other options as Window Maker is Unix / Linux graphical environment that fits better hackers, computer developers and system administrators.

Anyhow if you have some old family member that has to use an old computer architecture and the person is only to use mainly just browser to check email, youtube and basic surfing then Wmaker will be a great choice as it will consume little CPU and Memory much less than the heavy and computer resources sucking GNOME and KDE.

I've historically used Wmaker also with its teminal emulator rxvt (VT102 terminal emulator for the X Windows System) which is a kinda of improved version of xterm (the default terminal program bundled with Xorg server), but for those who are already used to Gnome Terminal nice tabs perhaps that would be not the terminal of choice.

rxvt was build to match well the look and feel of AfterStep and consequently Wmaker, its scrollbar was aiming to very much resemble NeXTStep style scrollbar


Most "custom" shortcuts are used to launch specific applications. To add your own keyboard shortcut for an application, go to the "Applications Menu Definition" panel in the Preferences app.  Select the application item in the menu for which you want to create a shortcut, then use the "capture" button to capture the keystrokes you want to assign to that item.  In the screenshot, I've assigned Mod1 + W to open Firefox.

Above  screenshot shows how to map the Run Application keyboard bind to behave like GNOME Run application ALT + F2


Customizing background of Window Maker

Because WMaker is so simple made and targetting more of a developer audience for use it doesn't have a special graphical interaface to set a Background if you like so, but instead you need to use a wmsetbg command to do so:

wmsetbg -s -u filename.jpg


WMSetBG command stands for WindowMaker Set Background

If you're too lazy to install and start configuring wmaker, there is a Window Maker LiveCD, you can run Window Maker through LiveCD in Virtual Machine such as VirtualBox to get feeling what you're about to get if you install and start using Wmaker on your Computer.


Well at first with Window Maker you might feel confused and quickly irritating missing the already established way to work with your computer, but that's just for a starter sooner you will realize, that for using a limited number of applications for work wmaker, makes you much more efficient. Moreover using your computer with Wmaker can rewire your brain circuits to think a little bit different.

Once you switched to Window Maker you will likely want to have a graphical option to connect to Wireless Networks especially if you're using Wmaker on a notebook it is convenient to not always manually do scan for networks with


commad and use wpasupplicant command to connect instead you can just install wicd and stop default Gnome Network Manager (called Network Manager), you can do so by running as root:

service network-manager stop
apt-get install wicd wicd-gtk
service wicd start
wicd-gtk &