Posts Tagged ‘sys admin’

Find all hidden files in Linux, Delete, Copy, Move all hidden files

Tuesday, April 15th, 2014

search-find-all-hidden-files-linux-delete-all-hidden-files
Listing hidden files is one of the common thing to do as sys admin. Doing manipulations with hidden files like copy / delete / move is very rare but still sometimes necessary here is how to do all this.

1. Find and show (only) all hidden files in current directory

find . -iname '.*' -maxdepth 1

maxdepth – makes files show only in 1 directory depth (only in current directory), for instance to list files in 2 subdirectories use -maxdepth 3 etc.

echo .*;

Yeah if you're Linux newbie it is useful to know echo command can be used instead of ls.
echo * command is very useful on systems with missing ls (for example if you mistakenly deleted it 🙂 )

2. Find and show (only) all hidden directories, sub-directories in current directory

To list all directories use cmd:

find /path/to/destination/ -iname ".*" -maxdepth 1 -type d

3. Log found hidden files / directories

find . -iname ".*" -maxdept 1 -type f | tee -a hidden_files.log

find . -iname ".*" -maxdepth 1 type d | tee -a hidden_directories.log
4. Delete all hidden files in current directory

cd /somedirectory
find . -iname ".*" -maxdepth 1 -type f -delete

5. Delete all hidden files in current directory

cd /somedirectory
find . -iname ".*" -maxdepth 1 -type d -delete

6. Copy all hidden files from current directory to other "backup" dir

find . -iname ".*" -maxdepth 1 -type f -exec cp -rpf '{}' directory-to-copy-to/ ;

7. Copy and move all hidden sub-directories from current directory to other "backup" dir

find . -iname ".*" -maxdepth 1 -type d -exec cp -rpf '{}' directory-to-copy-to/ ;

– Moving all hidden sub-directories from current directory to backup dir

find . -iname ".*" -maxdepth 1 -type d -exec mv '{}' directory-to-copy-to/ ;

 

10 must know and extremely useful Linux commands that every sys admin should know

Tuesday, July 30th, 2013

10 must know extremely useful gnu linux command line tools tips and tricks
There are plenty of precious command line stuff every admin should be aware on Linux. In this article I just decided to place some I use often and are interesting to know. Below commands are nothing special and probably many of experienced sys admins already know them. However I'm pretty sure novice admins and start-up Linux enthusiasts will find it useful. I know there much more to be said on the topic. So anyone is mostly welcome to share his used cmds.
 
1. Delete all files in directory except files with certain file extension

It is good trick to delete all files in directory except certain file formats, to do so:

root@linux:~# rm !(*.c|*.py|*.txt|*.mp3)

2. Write command output to multiple files (tee)

The normal way to write to file is by using redirect (to overwrite file) ">" or (to append to file) ">>";. However when you need to write output to multiple files there is a command called tee, i.e.:

root@linux:~# ps axuwwf | tee file1 file2 file3

3. Search for text in plain text file printing number of lines after match

Whether you need to print all number of lines after match of "search_text" use:

root@linux:~# grep -A 5 -i "search_text" text_file.txt

4. Show all files where text string is matched with GREP (Search for text recursively)

Searching for text match is extremely helpful for system administration. I use  grep recursive (capability) almost on daily basis:

root@websrv:/etc/dovecot# grep -rli text *
conf.d/10-auth.conf
conf.d/10-mail.conf
dovecot.conf

-l (instructs to only print file names matching string), -r (stands for recursive search), and -i flag (instructs grep to print all matches  inogoring case-sensitivity ( look for text nomatter if with capital or small letters)

5. Finding files and running command on each file type matched

In Linux with find command it is possible to search for files and run command on each file matched.
Lets say you we want to look in current directory for all files .swp (temporary) files produced so often by VIM and wipe them out:

root@linux:~# find . -iname '*.swp*' -exec rm -f {} \;

6. Convert DOS end of file (EOF) to UNIX with sed

If it happens you not have dos2unix command installed on Linux shell and you need to translate DOS end of file (\r\n – return carriage, new line) to UNIX's (\r – return carriage)), do it with sed:

root@linux:~# sed 's/.$//' filename

7. Remove file duplicate lines with awk:

cat test.txt
test
test
test duplicate
The brown fox jump over ...
Richard Stallman rox

root@linux:~# awk '!($0 in array) { array[$0]; print }' test.txt
test
test duplicate
The brown fox jump over ...
Richard Stallman rox

To remove duplicate text from all files in directory same can be easily scripped with bash for loop:

root@linux:~# for i in *; do
awk '!($0 in array) { array[$0]; print }' $i;
done

8. Print only selected columns from text file

To print text only in 1st and 7th column in plain text file with awk:

root@linux:~# awk '{print $1,$6;}' filename.txt ...

To print only all existing users on Linux with their respective set shell type:

root@linux:~# cat /etc/passwd|sed -e 's#:# #g'|awk '{print $1,$6;}'

9. Open file with VIM text editor starting from line

I use only vim for console text processing, and I often had to edit and fix file which fail to compile on certain line number. Thus use vim to open file for writing from necessary line num. To open file and set cursor to line 35 root@linux:~# vim +35 /home/hipo/current.c

10. Run last command with "!!" bash shorcut

Lets say last command you run is uname -a:

root@websrv:/home/student# uname -a
Linux websrv 3.2.0-4-686-pae #1 SMP Debian 3.2.46-1 i686 GNU/Linux

To re-run it simply type "!!":

root@websrv:/home/student# !!
uname -a
Linux websrv 3.2.0-4-686-pae #1 SMP Debian 3.2.46-1 i686 GNU/Linux

root@websrv:/home/student#

 

Installing Usual PHP Apache needed modules for new Debian GNU / Linux servers

Tuesday, September 18th, 2012

Almost evertime whether install a new Debian Linux server to host some websites, use the popular small and mid-sized hosting solution combination:
 

  • Apache webserver
  • PHP module to interpret the PHP programming code
  • MySQL to store the DB Backend

Installing the basis for on Debian is easy:


# apt-get install --yes apache2 apache2-mpm-prefork libapache2-mod-php \
mysql-server php5 php5-mysql mysql-client mysql-common phpmyadmin
....

This of course is in case, if necessery to run websites which are written to usephp code which is not thread safety (Use Apache child prefork technology to manage processes); For websites writen to be thread safety (not use some forking php functions like: php – exec(); fork(); etc. – I install apache2-mpm-prefork for better Webserver performance and speed.

This minimum collection of packages is good only for basic, websites and most Joomla, WordPress, Drupal or whatever custom PHP websites has to be hosted usually require much more PHP functions which are not part of this basic bundle. Hence as I said prior on almost all new Linux debian / ubuntu deb package based servers need to install following list of extra PHP deb packages:


# apt-get install --yes php-apc php-auth-ssl php-mail \
php-http php-net-smtp php-net-socket php-pear php5-cli php5-curl \
php5-gd php5-imagick php5-mapscript php5-mcrypt php5-odbc php5-sybase \
php5-xsl
...,

After installing this standard bundle of modules PHP is extended to support somenice functionalities like Image editting / convertion / resizing … various graphic editting functions as supported by infamous ImageMagick and GDlib, PEAR support (PHP Extension and Application Repository) bundle providing number of useful PHP classes.
php5-xInstalling Usual PHP Apache needed modules for new Debian GNU / Linux serverssl is usually necessery for websites which pass data in XSL format (a specific formatted XML data). php5-xsl is usually necessery for websites containing flash animationsPresentation, videos, games etc.

That is mostly it, hope this helps some sys admin like me who need configure new Debian based hosting server 🙂

How to test if imap and pop mail server service is working with Telnet cmd

Monday, August 8th, 2011

test-if-imap-pop3-is-working-with-telnet-command-logo-imap
I’ve recently built new mail qmail server with vpopmail to serve pop3 connectins and courierimap and courierimaps to take care for IMAP IMAPS.

I further used telnet to test if the Linux server pop3 service on (110) and imap on (143) worked fine, straight after the completed qmail install.
Here is how to test mail server with vpopmail listening for connections on pop3 port :

debian:~# telnet mail.mymailserver.com 110
Trying 111.222.333.444...
Connected to mail.mymailserver.com.
Escape character is '^]'.
+OK <2813.1312745988@mymailserver.com>
USER hipo@mymailserver.com
+OK
PASS here_goes_my_secret_pass
+OK
LIST
1 309783
2 64053
3 2119
4 64357
5 317893
RETR 1
My first mail content retrieved with RETR commandgoes here ....
quit
+OK
Connection closed by foreign host.

You see I have 5 messages in my mailbox, as you can see I used RETR command to check the content of my mail, this is handy as I can read my mails straight with telnet (if the mail is in plain text), of course it’s a bit more complicated if I have to read encrypted or html mail, though still its easy to write a tiny parser and pipe the content produced by telnet command to lynx or some other text based browser.

Now another sys admin handy tip is the use of telnet to check my mail servers IMAP servers is correctly operating.
Here is how:

debian:~# telnet mail.mymailserver.com 143
Trying 111.222.333.444...
Connected to localhost.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION STARTTLS] Courier-IMAP ready. Copyright 1998-2010 Double Precision, Inc. See COPYING for distribution information.
01 LOGIN hipo@mymailserver.com here_goes_my_secret_pass
A OK LOGIN Ok.
02 LIST "" *
* LIST (Unmarked HasNoChildren) "." "INBOX"
02 OK LIST completed
03 SELECT INBOX
* FLAGS (Draft Answered Flagged Deleted Seen Recent)
* OK [PERMANENTFLAGS (* Draft Answered Flagged Deleted Seen)] Limited
* 5 EXISTS
* 5 RECENT
* OK [UIDVALIDITY 1312746907] Ok
* OK [MYRIGHTS "acdilrsw"] ACL
03 OK [READ-WRITE] Ok
04 STATUS INBOX (MESSAGES)
* STATUS "INBOX" (MESSAGES 5)
04 OK STATUS Completed.
05 FETCH 1 ALL
...
06 FETCH 1 BODY
...
07 FETCH 1 ENVELOPE
...
As you can see according to standard to send commands to IMAP server from console after a telnet connection you will have to always include a command line number like 01, 02, 03 .. etc.

Using such a line numbering is not obligitory and also letters like A, B, C could be use still line numbering with numbers is generally a good idea since it’s easier for reading on the screen.

Now line 02 shows you available mailboxes, line 03 SELECT INBOX selects the imap Inbox to be further operated with, 04 STATUS INBOX cmd displays status about current mailboxes in folder.
FETCH 1 ALL instructs the imap server to get list of all IMAP message headers. Next command in line 05 FETCH 1 BODY will display the message body of the first message in list.
The 07 FETCH 1 ENVELOPE will display the mail headers for the 1 message.

Few other IMAP commands which might be helpfun on connection are:

08 FETCH 1 FULL
09 FETCH * FULL

First one would fetch complete content of a message numbered one from the imap server and the second one 09 FETCH * FULL will get all the mail content for all messages located on the remote IMAP server.

The STATUS command aforementioned earlier could take the following list of arguments:

MESSAGES, UNSEEN, RECENT UIDNEXT UIDVALIDITY

These commands are a gold mine for me as a sysadmin as it helps quickly solve problems, hope they would help to somebody out there as well 😉
This way is a way shorter than bothering each time to check, if some customer e-mail account is improperly configured by creating setting up a new account in Thunderbird.