When exchanging text files between Windows and AIX systems, you often run into ^M (CTRL-M) characters at the end of each line in a text file. To remove these ugly characters:

tr -d '^M' < [inputfile] > [outputfile]

# dos2unix [filename]

It's a good idea to centralize the shell history files for ease in tracking the actions done by the users:

Create a ${hist_dir}. Add the following lines to the /etc/profile file:

export HISTFILE=/${hist_dir}/${LOGNAME}_`date "+%Y%m%d_%H%M%S"`
export HISTSIZE=2000

A way to change the default 027 umask of ftp is to change the entry in /etc/inetd.conf for ftpd:

ftp stream tcp6 nowait root /usr/sbin/ftpd -l -u 117

daemon.info [filename]

How do you send an attachment via e-mail from AIX to Windows? Uuencode is the answer:

# uuencode [source-file] [filename].b64 | mail -v -s "subject" [email-address]

# uuencode /etc/motd motd.b64 | mail -v -s "Message of the day" email@hostname.com

# ( echo "This is the body";uuencode /etc/motd motd.b64 ) | mail -s "This is the subject" email@hostname.com

# uuencode file.tar file.tar | mailx -s "subject" email@hostname.com
# uuencode file.tar.gz file.tar.gz | mailx -s "subject" 
email@hostname.com

Adding a DVD-ROM with DLpar is very easy. Removing however, can be somewhat more difficult, especially when you've run cfgmgr and devices have been configured. This is how to remove it. Remove all cdrom devices found with lsdev -Cc cdrom:

# rmdev -dl cd0
# rmdev -dl ide0

# lsdev -C | grep pci

Defunct processes are commonly known as "zombies". You can't "kill" a zombie as it is already dead. Zombies are created when a process (typically a child process) terminates either abnormally or normally and it's spawning process (typically a parent process) does not "wait" for it (or has yet to "wait" for it) to return an exit status.

It should be noted that zombies DO NOT consume any system resources (except a process slot in the process table). They are there to stay until the server is rebooted.

Zombies commonly occur on programs that were (incompletely) ported from old BSD systems to modern SysV systems, because the semantics of signals and/or waiting is different between these two OS families.

See: http://www.hyperdictionary.com/dictionary/zombie+process

Let's say you have a helpdesk, where they must be able to run a script under user-id root to check or monitor a system:

First, create a script, you wish your helpdesk to run.

Modify your /etc/inetd.conf file and add:

check stream tcp wait root /usr/local/bin/script.sh

check 4321/tcp

# telnet [system] 4321

Use the following command to find any files that no longer have a valid user and/or group, which may happen when a group or user is deleted from a system:

# find / -fstype jfs \( -nouser -o -nogroup \) -ls

It sometimes occurs that a file system runs full, while a process is active, e.g. when a process logs its output to a file. If you delete the log file of a process when it is still active, the file will be gone, but the disk space will usually not be freed. This is because the process keeps the inode of the file open as long as the process is active and still writes to the inode. After deleting the file, it's not available as file anymore, so you can't view the log file of the process anymore. The disk space will ONLY be freed once the process actually ends.

To overcome it, don't delete the log file, but copy /dev/null to it:

# cp /dev/null [logfile]

In general IBM recommends that JFS log devices be set to 2MB for every 1GB of data to be protected. The default jfslog for rootvg is /dev/hd8 and is by default 1 PP large. In some cases, file system activity is too heavy or too frequent for the log device. When this occurs, the system will log errors like JFS_LOG_WAIT or JFS_LOG_WRAP.

First try to reduce the filesystem activity. If that's not possible, this is the way to extend the JFS log:

• Determine which log device to increase. This can be determined by its Device Major/Minor Number in the error log:

  # errpt -a

  An example output follows:

  Device Major/Minor Number
  000A   0003
  

  The preceding numbers are hexadecimal numbers and must be converted to decimal values. In this exmpale, hexadecial 000A 0003 equals to decimal numbers 10 and 3.
• Determine which device corresponds with these Device Major/Minor Numbers:

  # ls -al /dev | grep "10, 3"

  If the output from the preceding command reveals that the log device the needs to be enlarged is /dev/hd8 (the default JFS log device for rootvg), then special actions are needed. See further on.
• Increase the size of /dev/hd8:

  extendlv hd8 1

• If the jfslog device is /dev/hd8, then boot the machine into Service Mode and access the root volume group and start a shell. If the jfslog is a user created jfslog, then unmount all filesystems that use the jfslog in question (use mount to show the jfslog used for each filesystem).
• Format the jfslog:

  # logform [jsflog device]

  For example:

  logform /dev/hd8

• If the jfslog device is /dev/hd8, then reboot the system:

  # sync; sync; sync; reboot

  If the jfslog is a user created jfslog, then mount all filesystems again after the logform completed.