Print last column containing spaces and special characters

Question

I need a full path/command thats been execued to start a process thats exposed on the network - listens on tcp/udp . I did manage to get all of that using below "one liner":

netstat -nlp46|tail -n +3 |   while IFS=" " read -r -a line; 
do nb=${#line[@]}; 
PID=$(echo ${line[$((nb - 1))]} | awk -F'/' '{print $1}'); 
CMD=$(ps -ef|awk '$2 == '"$PID" |awk -F" " '{out=$8; for(i=9;i<=NF;i++){out=out""$i}; print out}');
echo $PID^$CMD; 
done

but when process contains some special characters in command line, eg thin server, script has some issues with following error

awk: line 1: missing ) near end of line

when I did run part of script against that process I had no problems

root@ftp-host02:~# PID=15000; COMMAND=$(ps -ef|awk '$2 == '"$PID" |awk '{out=$8; for(i=9;i<=NF;i++){out=out" "$i}; print out}'); 
echo $COMMAND

thin server (0.0.0.0:3000)

What I'm doing wrong here?

Thanks

Answer 1

The error is here: awk '$2 == '"$PID"

• if $PID is not strictly numeric, then you're doing an equality check against an unquoted string, so really, who knows how awk will interpret it?

  $ PID="3000)"
  $ echo hello | mawk '$2 == '"$PID"
  mawk: line 1: extra ')'
  

Passing the shell variable to awk as an awk variable (with the -v option) clears that up.

Cleaning up your code in other ways, we have:

netstat -nlp46 | 
tail -n +3 | 
while IFS=" " read -r -a fields; do 
    nb=${#fields[@]}
    PID=${fields[nb-1]%%/*}
    CMD=$( ps -ef | awk -v pid="$PID" '$2 == pid {out=$8; for(i=9;i<=NF;i++){out=out $i}; print out}' );
    echo "$PID^$CMD"; 
done

Notes:

• proper indentation goes a long way towards readable code
• the index of a numerically indexed array is already evaluated in arithmetic context so ${ary[n-1]} will work
• You can remove a slash and all subsequent characters with shell parameter expansion, so you don't need awk to get the PID
• you don't need to pipe awk into awk: consolidate
• pass a shell variable into awk with the -v option

Answer 2

Could you try that:

for i in $(netstat -atnp | awk '{ print $7 }' | grep ^[0-9] | awk -F\/ '{ print $1 }'); do echo "PID: $i " $(ps faxuwwww | grep $i); done