Why does a single process have many PIDs?

  #!/bin/bash
    #fauz-pas
    num=1
    bool=0
    while [ "$bool" -eq 0 ]
    do
    ps aux | grep "$1" | grep -v "color" | grep -v "grep"  > isahawk
    crazy="$(awk -F" " '{print $2}' isahawk)"
    echo x"$crazy"x
    kill $crazy 2> error
    if [ "$crazy" = "" ]
    then
    echo ":_ $crazy: No such process"
    bool=1
    echo "ha,finally"
    fi
    sleep 1
    done

This is a script to kill a process
I expect to get a single pid as an output but rather i get a list

Output

:~$ ./kil\ vlc vlc
x17311
17363
17561
17794
18033
18139
18278
18335
18337
18371
18452
19196
19199
19213
19230
19262
19326
19354
19369
19380
19389
19409
19925
19936x
Terminated

Output of ps aux | grep "vlc"

ubuntu   20127  4.5  1.5 868204 59788 ?        Sl   14:24   0:00 /usr/bin/vlc --started-from-file
ubuntu   20139  0.0  0.0  14224  1012 pts/2    S+   14:24   0:00 grep --color=auto vlc

Output of pgrep vlc

Passerby

Posted 2019-03-15T08:49:05.893

Reputation: 1

1Have you tried looking at the full ps output that you're processing (before cutting off the PID)? The other fields might tell you what the extra processes belong to, and whether they're false positives. Also – have you considered using pgrep? – user1686 – 2019-03-15T08:52:05.253

If they are indeed false positives?? Why are they showing up ? – Passerby – 2019-03-15T09:08:03.243

1Because that's the definition of a false positive? Something that matches your criteria while you don't intend it to match. Looking at your output you should already realize that your grep and awk are not working as intended. – Seth – 2019-03-15T09:16:50.333

1Why such a rube-goldburg solution to kill a process/list of processes? Your grep command is finding unrelated processes, and you can look at the isahawk file to see what it found because you are not cleaning up after yourself. – davidgo – 2019-03-15T19:00:48.543

The above comment is right, you should examine isahawk. Nobody noticed you had named the script "kil vlc". It detects and terminates itself (therefore Terminated), regardless of whether vlc is running or not. Everything after kill $crazy is futile. – Kamil Maciorowski – 2019-03-27T20:19:36.417

Why does a single process have many PIDs?

No answers