Often when you run vmstat, the output may be looking very disorganized, because of column values not being shown properly under each row. A very simple solution to this issue is to run the same command with the "-w" flag, which will provide you with a wide vmstat output:

# vmstat -w

When you change MAXUPROC (Maximum number of processes allowed per user), the smitty help panel will tell you that changes to this operating system parameter will take effect after the next system reboot.

This is wrong Help information. The change takes effect immediately, if MAXUPROC is increased. If it is decreased, then it will take effect after the next system reboot.

This help panel text from smitty will be changed in AIX 5.3. APAR IY52397.

How to do an automatic FTP from within a script:

• -n prevents automatic login and -v puts it in verbose mode
• asciorbin_Type should be set to either ascii or binary
• grep for $PHRASE (particular return code) from $LOGFILE to determine success or failure

ftp -nv $REMOTE_MACHINE < $LOGFILE 
user $USER_NAME $USER_PASSWORD 
$asciorbin_Type 
cd $REMOTE_PATH 
put $LOCAL_FILE $REMOTE_FILE 
quit 
! 
grep $PHRASE $LOGFILE 

Use the following command to interactively find and remove core dumps on your system:

# find / -name core -exec file {} \; -exec rm -i {} \;

To discover the amount of paging space a proces is using, type:

# svmon -wP [proces-id]

To kill all processes of a specific user, enter:

# ps -u [user-id] -o pid | grep -v PID | xargs kill -9

# fuser -k /dev/pts[#]

# su - [user-id] -c kill -9 -1

Searching with grep in directories with large amounts of files, can get the following error:

The parameter list is too long

# ls | xargs grep "[search string]"

# ls | xargs grep -i "error"

The pwd command will show you default the logical directory (pwd -L = default), which means, if any symbolic links are included in the path, that is, what will be shown. To show you the actual physical directory, use the next undocumented feature:

# pwd -P

When you receive an error like:

Do not specify an existing file

# iptrace -u

Where did all these routes come from & why is my system sending ICMP packets every 10 minutes? This is caused by path MTU discovery. If your AIX system is sending ICMP packets, you can disable it:

AIX has a feature called path MTU discovery which is based on ICMP packets in order to learn MTU sizes on the LAN. Path MTU discovery is a way of finding out the maximum packet size that can be sent along a network using ICMP packets and is enabled on AIX by default. This is done to avoid IP fragmentation on heterogenous networks (ie, an ATM network connected to an ethernet network) and is described in RFC 1191.

# no -a | grep discover

# no -p -o tcp_pmtu_discover=0
# no -p -o udp_pmtu_discover=0