Posts Tagged ‘mistake’

How to promptly interrupt Windows shutdown in case of shutdown, restart mistake

Thursday, April 17th, 2014

Its really annoying, when some Anti-Virus software or application updates itself and requires a Windows restart. It is even more annoying when you have 50 windows opened and suddenly they start closing one by one. In such cases it is precious to know there is way to Cancel Windows Shutdown using command line:

Just press Windows (button) + R: type in;

shutdown /a

and press enter.

That's it a quick cmd prompt will flash through the screen and Windows will stop shutdowning 🙂 Enjoy

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Linux: Rename all files extension from upper to lower cases

Friday, February 14th, 2014

Lets say you're an admin involved in webhosting and due to a programmer's mistake, you end up with directory full with files with extension in upper cases but for actual version of website (all pictures are red only in lower cases), hence would like to transform these to lower cases.
To give an example, to illustrate what I mean, lets say you have in a directory files like;

filename.JPG, picture.PNG, new-picture.GIF

and you would like all files to be renamed to lower extension characters, i.e.:

filename.jpg, picture.png, new-picture.gif.

# find . -name '*.*' -exec sh -c 'a=$(echo {} | sed -r "s/([^.]*)\$/\L\1/"); [ "$a" != "{}" ] && mv "{}" "$a" ' \;

That's all enjoy 🙂

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Resolving messed up console / terminal on GNU Linux / A tiny old school hack ;)

Thursday, September 26th, 2013

Resolve fix messed up unreadable gnu linux console terminal screenshot

Its probably not so common problem among new-comer Linux users / admins but sooner or later even those who haven't will cat by mistake (or on purpose) some binary file end result will be physical console / terminal / SSH Client (lets say PuTTY) will display some non-sense characters and whether typing you will type in some "alien language" characters this continues until you close up console and re-login. Of course its not such a big problem to re-login or (kill active SSH session).

fix terminal after showing displaying binary file by mistake catting wrong file incident

But there is no sense to do that and loose time and most importantly loose your logged in session (especially if you have hopped to 4 ssh sessions and you forgot to run GNU / screen). Thus its handy to know about

# reset

command. Once issued in most cases TTY messed up characters gets fixed up. However if even reset doesn't fix it, there is another "hack" to resolve it with no need for relogin. This is an old hack from my old Linux days and not so popular among admins, here is how:



press Enter

and then press

Ctrl + O (Ctrl ^ O)


then press Enter

and then again press

Ctrl + D (Ctrl ^ D)

Nice hack isn't it ? 🙂

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Change default browser to Internet Explorer

Wednesday, September 18th, 2013

Almost no sane person and security aware person uses Internet Explorer still. However still in huge American companies it is heavily used. If you install Firefox or Google Chrome and by mistake you change default browser to one of them then it is worthy revert back default browser to Internet Explorer.

Here is how to do it;
Open Internet Explorer and navigate to:

Tools -> Interent Options -> Programs -> click on (Make Default)




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ClamTK Linux Desktop Anti-Virus program – Checking Windows mapped drives with ClamTK

Thursday, June 20th, 2013

Linux desktop graphical program to scan for-viruses ClamTK clamav frontend application

In general Linux has fame for being Virus Free Operating System. During the 13 last years as dedicated GNU / Linux user, I've seen Linux servers with binaries infected with Viruses, however the hosts, were severely messed hosts because noone updated them on time and script kiddy crackers has "hacked" multiple times. In lifetime one of my old testing computers got infected with Virus because of my mistake of running "suspicious" pre-compiled "cracker" software binaries with no MD5 verification and "questionable" websites…
I share this story because, I want to beat-up the Myth that Linux cannot have Viruses. It CAN but not very likely to happen 🙂

As a Desktop user over the last 10 years, even though I installed plenty of packages from third party sources and never happened to infect my computer with Virus – or at least if I infected I never knew it. A lot of popular MS-Windows Anti-Virus programs, has already ports for Linux. Just to mention few non-free Linux AV software providing install binaries;

  • Avast

  • BitDefender

  • AVG

  • Dr. Web

Though risk of Viruses on Linux is so tiny, it is useful to have ANTI-Virus Software to check files received from Skype, E-mails and onse downloaded with Browser. I always prefer so until now I used Clamav Antivirus to keep an eye periodically on my Desktop Linux host and servers running mail servers (those who run Mail Servers know how useful is Clamav in stopping tons of E-mail attached Malware Viruses and Trojans).

I use mostly Debian Linux, so on every new server or Desktop one of first things I did was to install it, i.e.:

# apt-get --yes install clamav

Before I knew Clamav AV for Windows has GUI, anyways till recently I didn't know if there is some kind of free software AV Graphical frontend for Linux. I just found out about ClamTK

Linux Free Antivirus ClamTk clamav Virus Scanner graphical frontend

ClamTK is available in most Linux distributions from default package repositories

On Debian and Ubuntu to install it run common:

debian:~# apt-get --yes clamtk

On Fedora and CentOS Linux to install:

[root@fedora ~]# yum -y install clamtk

Its best to run it as root superuser (or via sudo) to make ClamTK able read all files or mounts on system:

hipo@debian:~$ sudo clamtk

ClamTK is very simple to use and there are only few configuration options;
clamtk desktop linux free antivirus startup preferences

clamtk scan for viruses linux gui proxy

linux Anti-Virus Desktop graphics  easy to use AntiVirus ClamTK preferences screenshot

ClamTK is very useful when used with mounted Samba Shared (Mapped) Windows drives to scan for Viruses and malware, i.e, after mounting share using cmd like:

# smbmount // /mnt/projects -o user=USERNAME

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Install jwchat web chat jabber interface to work with Debian ejabberd jabber server

Wednesday, January 4th, 2012

JWChat ejabber jabber Ajax / HTML based client logo

I have recently blogged how I've installed & configured ejabberd (jabber server) on Debian .
Today I decided to further extend, my previous jabberd installation by installing JWChat a web chat interface frontend to ejabberd (a good substitute for a desktop app like pidgin which allows you to access a jabber server from anywhere)

Anyways for a base of installing JWChat , I used the previously installed debian deb version of ejabberd from the repositories.

I had a lot of troubles until I actually make it work because of some very minor mistakes in following the official described tutorial ejabberd website jwchat install tutorual

The only way I can make jwchat work was by using the install jwchat with ejabberd's HTTP-Bind and file server method

Actually for quite a long time I was not realizing that, there are two ways to install JWChat , so by mistake I was trying to mix up some install instructions from both jwchat HTTP-Bind file server method and JWchat Apache install method

I've seen many people complaining on the page of Install JWChat using Apache method which seemed to be experiencing a lot of strangle troubles just like the mines when I mixed up the jwchat php scripts install using instructions from both install methods. Therefore my guess is people who had troubles in installing using the Apache method and got the blank page issues while accessing as well as various XML Parsing Error: no element found errors on – is most probably caused by the same install instructions trap I was diluted in.

The steps to make JWChat install using the HTTP-Bind and file server method, if followed should be followed absolutely precisely or otherwise THEY WILL NOT WORK!!!

This are the exact steps I followed to make ejabberd work using the HTTP-Bind file server method :

1. Create directory to store the jwchat Ajax / htmls

debian:~# mkdir /var/lib/ejabberd/www
debian:~# chmod +x /var/lib/ejabberd
debian:~# chmod +x /var/lib/ejabberd/www

2. Modify /etc/ejabberd/ejabberd.cfg and include the following configs

While editting the conf find the section:


Scrolling down you will fine some commented code marked with %% that will read:

{5269, ejabberd_s2s_in, [
{shaper, s2s_shaper},
{max_stanza_size, 131072}

Right after it leave one new line and place the code:

{5280, ejabberd_http, [
{request_handlers, [
{["web"], mod_http_fileserver}


Scrolling a bit down the file, there is a section which says:

%%% =======

%% Modules enabled in all ejabberd virtual hosts.

The section below the comments will look like so:

{modules, [ {mod_adhoc, []},
{mod_announce, [{access, announce}]}, % requires mod_adhoc
{mod_caps, []},
{mod_configure,[]}, % requires mod_adhoc
{mod_ctlextra, []},
{mod_disco, []},
%%{mod_echo, [{host, "echo.localhost"}]},
{mod_irc, []},
{mod_last, []},

After the {mod_last, … the following lines should be added:

{mod_http_bind, []},
{mod_http_fileserver, [
{docroot, "/var/lib/ejabberd/www"},
{accesslog, "/var/log/ejabberd/webaccess.log"}

3. Download and extract latest version of jwchat

Of the time of writting the latest version of jwchat is jwchat-1.0 I have mirrored it on pc-freak for convenience:

debian:~# wget

debian:~# cd /var/lib/ejabberd/www
debian:/var/lib/ejabberd/www# tar -xzvf jwchat-1.0.tar.gz
debian:/var/lib/ejabberd/www# mv jwchat-1.0 jwchat
debian:/var/lib/ejabberd/www# cd jwchat

4. Choose the language in which you will prefer jwchat web interface to appear

I prefer english as most people would I suppose:

debian:/var/lib/ejabberd/www/jwchat# for a in $(ls *.en); do b=${a%.en}; cp $a $b; done

For other languages change in the small one liner shell script b=${a%.en} (en) to whatever language you will prefer to make primary.After selecting the correct langauge a rm cmd should be issued to get rid of the .js.* and .html.* in other language files which are no longer needed:

debian:/var/lib/ejabberd/www/jwchat# rm *.html.* *.js.*

5. Configure JWChat config.js

Edit /var/lib/ejabberd/www/jwchat/config.js , its necessery to have inside code definitions like:

/* If your Jabber server is, set this: */
var SITENAME = "";

/* If HTTP-Bind works correctly, you may want do remove HTTP-Poll here */
name:"Native Binding",
description:"Ejabberd's native HTTP Binding backend",

6. Restart EJabberd server to load the new config settings

debian:~# /etc/init.d/ejabberd restart
Restarting jabber server: ejabberd..

7. Test JWChat HTTP-Bind and file server backend

I used elinksand my beloved Epiphany (default gnome browser) which by the way is the browser I use daily to test that the JWChat works fine with the ejabberd.
To test the newly installed HTTP-Bind ejabberd server backend on port 5280 I used URL: had quite a struggles with 404 not found errors, which I couldn't explain for half an hour. After a thorough examination, I've figured out the reasons for the 404 errors was my stupidity …
The URL was incorrect because I fogrot to move jwchat-1.0 to jwchat e.g. (mv jwchat-1.0 jwchat) earlier explained in that article was a step I missed. Hence to access the web interface of the ejabberd without the 404 error I had to access it via:

JWChat Ejabber webchat Epiphany Linux screenshot

Finally it is handy to add a small index.php redirect to redirect to

The php should like so:

header( 'Location:' ) ;

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Fix 503 AUTH first (#5.5.1) mail receive errors in Qmail

Friday, September 2nd, 2011

I have one qmail rocks install based on Thibbs Qmalrocks tutorial

I had to do some changes, to:
/etc/service/qmail-smtpd/run and /etc/service/qmail-smtpdssl/run init scripts.

After a qmail restart suddenly qmail stopped receiving any mail messages and my sent messages was returned with an error:

Connected to but sender was rejected.
Remote host said: 503 AUTH first (#5.5.1)

After investigating the issue I finally found, that one value I’ve changed in /etc/service/qmail-smtpd/run and /etc/service/qmail-smtpdssl was causing the whole mess:

The problematic variable was:


To solve the issue I had to disable the value which it seems, I have enabled by mistake.

Below is a quote from which explains what REQUIRE_AUTH shell variable does:

Setting REQUIRE_AUTH=1 will make the service not accept ANY mail unless the client has sent a valid AUTH command. This also prevents incoming mail from being accepted for your own domains, so do not use this setting if the service is accepting “normal” mail from the outside world.
Restarting via qmailctl restart and qmail started receiving messages normal 😉

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How to fix “delivery 1: deferral: Sorry,_message_has_wrong_owner._(#4.3.5)/” qmail mail delivery failure message

Friday, May 20th, 2011

After a failed attempt to enable some wrapper scripts to enable domain keys support in a qmail powered mail server my qmail server suddenly stopped being able to normally send mail.

The exact error message which was logged in /var/log/qmail/current was:

@400000004dd66fcc16a088ac delivery 1: deferral: Sorry,_message_has_wrong_owner._(#4.3.5)/

This qmail messed happened after I substituted /var/qmail/bin/qmail-queue and /var/qmail/bin/qmail-remote with two respective wrapper shell scripts which were calling for the original qmail-queue and qmail-remote binaries under the names qmail-queue.orig and qmail-queue.orig

Restoring back qmail-queue.orig to /var/qmail/bin/qmail-queue and qmail-remote.orig to /var/qmain/bin/qmail-remote and restarting the mail server broke my qmail install.

After a bunch of nerves trying to isolate what is causing the error I found out that by mistake I forgot to copy the qmail-queue and qmail-remote permissions and ownership.

Thus I had to check another qmail working installation’s permissions for both binaries and fix the permissions to be equivalent to the permissions:

debian:~# ls -al /var/qmail/bin/qmail-remote
-rwx–x–x 1 root qmail 50464 2011-05-20 12:56 /var/qmail/bin/qmail-remote*
debian:~# ls -al /var/qmail/bin/qmail-queue
-rws–x–x 1 qmailq qmail 20392 2011-05-20 12:56 /var/qmail/bin/qmail-queue*

The exact chmod and chmod commands I issued to solve the shitty issues were as follows:

First I fixed the qmail-queue and qmail-remote ownership:

debian:~# chown qmailq:qmail /var/qmail/bin/qmail-queue
debian:~# chown root:qmail /var/qmail/bin/qmail-remote

Second I set the proper file permissions:

# make the qmail-queue binary suid
debian:~# chmod u+s /var/qmail/bin/qmail-queue
debian:~# chmod 611 /var/qmail/bin/qmail-queue
debian:~# chmod 611 /var/qmail/bin/qmail-remote

Third and last I did a restart of the qmail server and tested it sends properly

debian:~# /usr/bin/qmailctl stop
Stopping qmail...
debian:~# /usr/bin/qmailctl start
Starting qmail

Finally to test that the qmail server qmail-queue was queing and sending with qmail-remote I used the system mail command like so:

debian:~# mail -s "test email"

Afterwards the mail was properly received on my mail account immediately.

In my /var/log/qmail/current log file all seemed fine:

@400000004dd6702a2eb2b064 starting delivery 1: msg 85281596 to remote
@400000004dd6702a2eb2b834 status: local 0/20 remote 1/20
@400000004dd6702b34cc809c delivery 1: success:
@400000004dd6702b34cc886c status: local 0/20 remote 0/20
@400000004dd6702b34cc8c54 end msg 85281596

The test mail was properly received on my mail account immediately.

It took me like half an hour to figure out what exactly is wrong with the permissions in situations like this I really wanted to change all my qmail installs with postfix and forget forever I ever used qmail …

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What’s going around Lately

Saturday, April 19th, 2008

Nothing special. Last week went just fine thanks to the Lord ! Of Course :). It was mostly peaceful. What was interesting was a method our teacher at management choose to use to make us better understand ourselves. She said I want all of you to draw me a picture of how do you foresee yourself ten years from now :). We all was surprised but just as she requested we did draw the pictures. My picture had 4 possibly futures. In one of them I was with my wife and a kid in front of our house, on the other I was owning and leading an IT company. On one of them I was helping to get out of the terrible pit of depression, addiction to drug, alcoholism, telling them “Stop there is a reason to live, God Loves you!”. In the other case I was a Senior SysAdmin in a middle size/big company managing servers/clusters. Now we had to make a report explaining our picture. I just did make my report hope the teacher would like it. Yesterday, Bino came home and proposed to go out, we went out we saw Stoyan (who btw is a Brother in Christ). Later we saw Dancho a friend of mine (a communist). First we started a normal talk later the talk just transformed into a terrible and useless argue I did a mistake not stopping whenever I had to. And in the end we decided not to see each other because it’s bad for both of us. Later Alex (an ex class-mate) called me and we went we had a walk in the central park and talked ’bout if I can say it like this “the life, the universe, and everything else” :). The next few weeks outline to be a tough one. We are going to have a lot of exams 8 or 9 ! We had a lot of projects and assignments but still I trust on the Holy one to help me make all of them and do just fine on the exams just like he helped me the last semester and the previous year.END—–

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