For the following code:

ps auwx | awk -v "PID=${PID}" '$2 == PID {print $LN}'

Hard to tell what you want - so I did this:

ps auwx | awk -v "PID=${PPID}" '$2 == PID {print }'
xxxxxxx  598114  0.0  0.0  956 1048      - A    08:48:02  0:00 sshd: xxxxxxx@pts/1
prdrept:logs :ps auwx | awk -v "PID=$$" '$2 == PID {print }'
xxxxxxx  479452  0.0  0.0  752  800  pts/1 A    08:48:02  0:00 -ksh

Hi "awk", Thanks and sorry for not clarifying enough.

The line is part of a running and working bash script on Linux.
PID is a local variable and the awk line is using its value to print the relevant line from ps.
I don't want to change the code (unless I have too), rather understand why it is used that way.

to simplify it, it is something like:

function foo()
{
   local MY_PID=""
   #...
   MY_PID=get_my_pid
   LINE=`ps auwx | awk -v "PID=${MY_PID}" '$2 == PID {print $LN}'`
   do_something "${MY_PID}"
}

anyone knows something about the $LN ?

It's not allowed to bump your thread to the top and pushing other peoples threads to the bottom.
Please read our rules.

The $ sign is used to print fields and AFAIK LN is not an awk variable.....

Regards