List Tar file contents on AIX

tar -tvf filename.tar

Change core file path for IBM HTTP Server 2.0.47

To change the default path where the core file is dumped for IBM HTTP Server 2.0.47 on AIX
1- Go to IBM HTTP server conf directory (ex: /usr/IBMIHS/conf)
2- Open httpd.conf
3- Edit the "CoreDumpDirectory" to the required directory (ex: CoreDumpDirectory "/usr/IBMIHS/corefiles")

Kill signal to dump core file

To kill a process and make it dump a core file, use the "6" signal
kill -6 PID

How to enable full core on AIX

1- To obtain full core files on AIX, set the following ulimit options:
ulimit -c unlimited turn on corefiles with unlimited size
ulimit -n unlimited allows an unlimited number of open file
descriptors
ulimit -d unlimited sets the user data limit to unlimited
ulimit -f unlimited sets the file limit to unlimited

You can display the current ulimit settings with:
ulimit -a

2- Set the following in smitty:
1. Start smitty as root
2. Go to System Environments -> Change/Show Characteristics of Operating System
3. Set the Enable full CORE dump option to TRUE

Alternatively, you can run chdev -l sys0 -a fullcore='true' as root.

You can check the setting with lsattr -D -c sys -a fullcore -H, which should produce output similar to this:
attribute deflt description user_settable
fullcore false Enable full CORE dump True

Reference: IBM Web Site, AIX Help

Add a job to crontab that runs every minute on AIX

• crontab -e
• 0-59 * * * * hobba

crontab -e: opens a text file (via vi) to add your job

0-59: is to run every minute

hobba: is the command to run, it's either a Unix command or a script

crontab logs on AIX 5.3

/var/adm/cron/log

Extract a certain file to a certain directory from a tar archive using GNU Tar

"gtar -C hobba -xvf aamr.tar aamr/1"

where:

"hobba" is the directory to extract to
"aamr.tar" is the archive from which we'll extract the file
"aamr/1" is the file inside the archive to be extracted to the destination directory (hobba).

A more convenient alternative to AIX tar; gtar

Searched everywhere just to know how to use the "tar" command to extract an archive to a certain folder instead of extracting it using the same directory structure inside, and so here are the steps:

1. Don't use the "tar" program
2. Download the GNU tar rpm from the AIX toolbox
3. Install it "rpm -ivh blablabla.rpm", you must have installed rpm at first from there of course, note that you must have root access to install that package
4. logout and then back in, use "gtar" from now on.

How to edit scheduled jobs (crontab) on AIX

A very useful link: http://publib.boulder.ibm.com/infocenter/discover/v8r4/index.jsp?topic=/com.ibm.discovery.ds.publish.doc/c_UG_Configuring_Cron_Job.htm

How To Find and Delete Files Not Matching MULTIPLE criteria using bash in AIX

"find . ! -name "*.bz2" ! -name "ESPRD*" | xargs rm"

 The above command finds all files in the "current" directory excluding those with "*.bz2" extension and those which start with "ESPRD*" and then deletes them all.

Script to monitor a Filesystem on AIX

#!/bin/sh

# This script checks if the /siebel filesystem reaches 2 GB of free space
# And then delete the old logs except those of today

warninglimit=2097152    # This number is in KB, it's equal to 2 GB,
                        # KB is used to avoid floating point numbers

filesystems="/siebel"   # List of filesystems to be monitored, separated by
                        # blank spaces

for fs in $filesystems  # Loop on the list of filesystems above
do
        size=`df -k $fs|grep $fs|awk '{ print $3; }'`   # Extract size of
                                                        # Filesystem in KB
        if [ $size -le $warninglimit ]  # If fs size is less than warning lim.
        then
                echo "WARNING: Low disk space for $fs ($size)"
                # Add what to delete here
        fi
done

How to ensure the integrity of your VERY LARGE files on AIX

Something that I've learnt by time is that I must check my files - especially big ones - upon transferring them from one medium to another or through a network or you're really going to face troubles that you'll see everyday in your worst nightmares :(. Anyway, it's very simple and quite fast, there are lots of methods available and here are my favourite two:

1. "csum -h MD5 file_name" #for small files, it's very fast
   
2. If the above doesn't work, use this instead "cksum file_name" #For very large files

Both will produce an output for you that will consist of numbers, characters or both, just do this on the source medium and the destination medium (after file transfer) and if the outputs match, the file is healthy, otherwise you must re-transfer the file and re-calculate the sum, Enjoy!

Getting X11 forwarding through ssh working after running su in AIX

After logging to a remote server using the "ssh -X user@host" (assuming that you have enabled X11Forwarding in your "/etc/ssh/sshd_config" file, and then restarted ssh by issuing "stopsrc -g ssh" and then "startsrc -g ssh"), you can run any X-windows application you want ONLY WITH THE USER YOU USED TO LOGIN FROM THE BEGINNING. Whenever you switch your user using "su - username", you won't be able to run any graphical application due to the following two problems:

1. The $DISPLAY variable value is lost
2. X authentication is based on cookies -- secret little pieces of random data that only you and the X server know... So, you need to let the other user know what your cookie is

To solve problem one, you can simply add this entry to your "/etc/profile": "export DISPLAY=localhost:10.0"

To solve problem two, you'll have to do the following after login to the server:

1. run the command "xauth list" to request the cookie for the current DISPLAY that's connecting to your X server, you'll receive something like that: somehost.somedomain:10 mit-magic-cookie-1 4d22408a71a55b41ccd1657d377923ae
2. Switch to the other user by issuing "su - username"
3. Copy the above response and paste it to produce this command "xauth add somehost.somedomain:10 mit-magic-cookie-1 4d22408a71a55b41ccd1657d377923ae"
4. Important Note: You'll have to repeat the above steps every time you use ssh to login to a server.

Example Scenario (Commands are in bold):
"ssh -X root@10.11.12.117"
"xauth list" Output -> "xyosd/unix:10 MIT-MAGIC-COOKIE-1 321c1d6b5bf22484395d0e05b0a29104"
"su - ahmad"
"xauth add xyosd/unix:10 MIT-MAGIC-COOKIE-1 321c1d6b5bf22484395d0e05b0a29104"

Article Resources: "http://www.debian-administration.org/articles/494"

How to increase AIX swap space

"lsps -a"

This will display something like:

Page Space Physical Volume Volume Group Size %Used Active Auto Type
hd6 hdisk0 rootvg 512MB 1 yes yes lv

This means that hd6 is the logical volume used for paging. To increase it, use the following command:

"extendlv hd6 10G"

This will add 10G of space to hd6, now reboot and then re-run "lsps -a" or you can simply use the "topas" command to check the paging space available.

How to solve the error: 452 Error writing file: A file cannot be larger than the value set by ulimit

When trying to transfer a very big file (over ftp for example), you'll receive the error above, this limit is a security limit in AIX and you can solve it by simply editing the /etc/security/limits file and increasing the "fsize" limit or simply changing it to "-1" to be unlimited, and then retry your transfer, you don't have to restart the machine for changes to take effect.

Ubuntu Connect to AIX V5.3 XServer

How to redirect graphical output of AIX to Ubuntu and run:

1) Go to System ->Administration ->Login Window->Security-> untick "Deny TCP connections to Xserver"
2) Log out and then back in
3) Type these commands in the terminal:
xhost +
telnet host_name
export DISPLAY=Client_IP:0.0
4) Run whatever x-application you need :)