The sample showlsnrs Korn shell script illustrates how to do the following in the Korn shell:

1. Use the AIX kdb command to determine the process communicating via an established TCP connection.

   #
   # Define function to use kdb to find process ID associated with a PCB control block
   #
   getproc()
     {
     echo "sockinfo $1 tcpcb" | kdb | grep "^pvproc" | read pvproc procname active hex1 hex2 rest
     echo $((16#$hex1))    # Convert PID from hex to decimal and return it
     }
   

   Because the AIX kdb command makes use of the /dev/mem special file, it requires root privilege.
   
   The PCB control block address (required as a parameter to the sockinfo subcommand of kdb) can be obtained using the AIX netstat command:

   netstatcmd='netstat -Aan'       # AIX netstat command to display network connections
   established='ESTABLISHED'       # State of connection when established
   $netstatcmd | grep $ipaddr | while read netline
   do
     set - $netline        # Parse netstat output line into positional parms
     pcbaddr=$1            # PCB control block addr is first token
     eval "connstate=\$$#" # Connection state is last token
     if [ "$connstate" == $established ]
     then
       pid=$(getproc $pcbaddr)     # Extract process ID from PCB control block
   

2. Convert a hexadecimal number to a decimal number.

     echo $((16#$hex1))    # Convert PID from hex to decimal and return it
   

   The Arithmetic evaluation in the Korn shell or POSIX shell article is intended to document this technique, but as of 11/5/2009, the documentation there is not clear. Feedback has been submitted to request that the article be revised so it is clearer.

3. Use the Korn shell eval special built-in command to compute the name of a shell environment variable before setting

     eval "hdr$line='$netline'"       # Save header line
   

   or referencing

     eval "connstate=\$$#"       # Connection state is last token
   

   the variable.

4. Determine the length of a character string in a shell environment variable

     linelng=${#netline}           # Get length of netstat output line
   

   The Parameter substitution in the Korn shell or POSIX shell article documents this technique

   Please help! There might well be better ways of performing the operations listed above in the Korn shell. Please use the Add Comment link at the bottom of the page to inform others of better Korn shell techniques than those described above. Thanks! (Note: Until you sign up and log in (using links in the upper right corner of this web page), you will not see the Add Comment link and you can not add a comment.)