As of Hardware Management Console (HMC) Release 3, Version 2.3, the rexec command is no longer available on the HMC. Use ssh command instead. From Version 2.5, users are required to enter a valid HMC user id/password when downloading the WebSM client from the HMC. The URL for the WebSM client is: http://[HMC fully qualified domain name]/remote_client.html.

Standard users receive the restriced shell via a set -r in .mysshrc when logging in. Comment the set -r command in /opt/hsc/data/ssh/hmcsshrc to get rid of the restricted shell for your users (it gets copied to $HOME/.mysshrc). For more information on commands that can be used in restriced shell on the HMC, go to HMC Power 4 Hints & Tips.

A special hscpe user ID can be created which has unrestricted shell access via the pesh command. Use lshmc -v to determine the serial number of the HMC (after *SE). Then call IBM support and request for the password of the hscpe user for the pesh command. IBM is able to generate a password for the hscpe user for one day.

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

To display line numbers in VI: Press ESC, then type

:set number

:set nonumber

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

The uname -Ls command will show you the partition number and the partition (lpar) name. When setting the resource allocation for a partition profile, set the minimum to the absolute bare minimum, and set the maximum as high as possible.

For memory there are special considerations:

• If you set the maximum too low and you wish to exceed above the maximum amount of memory defined in the active profile, you can't simply adjust the profile and put extra memory in via DLPAR, because the LPAR has been initialized with a certain page table size, based on the maximum amount of memory setting. Therefore, a reboot will be required when you wish to use more memory than defined in the active profile. If you do try it however, you'll receive the following error:

  HMCERRV3DLPAR018: There is no memory available for dynamic logical partioning on this partition.

• If you set the maximum too high, the partition will be initialize with a large page table size, which uses too much memory for overhead, which you might never use.