How to check if Process is active from a file which contains list of PID?

Question

So I have a .txt file which contains a list of PIDs and I want to write a shell script to check which of those PIDs are active.

My File.txt looks like-

I want to read the file line by line and check if that particular PID is active or not and if not then remove only that PID from the file.

Which states of a process would you consider active and non-active? — M. Becerra, Feb 20 '18 at 09:53

P.... · Answer 1 · 2018-02-20T12:35:27.940

1

Here inputFile is the source file containing pids

awk 'NR==FNR{p[$1]=$1;next} $2 in p{print $2}' inputFile <(ps -eaf) >inputFile.tmp && mv inputFile.tmp inputFile

Details:

Following will print the ps result for the process currently running which are also present in your file.

awk 'NR==FNR{p[$1]=$1;next} $2 in p' inputFile <(ps -eaf)

Following will create a tmp storage and create your desired file with only running pids.

>inputFile.tmp && mv inputFile.tmp inputFile

edited Feb 20 '18 at 12:35

answered Feb 20 '18 at 10:09

P....

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Using `cat` in a process substitution to feed Awk a regular file is pretty crazy. – tripleee Feb 20 '18 at 10:22
@tripleee could not think of any alternate way to use `ps` and `file` both as input to `awk`. without using `pipe` – P.... Feb 20 '18 at 12:31
Seriously? `awk 1 <(cat file)`can be rewritten `awk 1 file` – tripleee Feb 20 '18 at 12:32
@tripleee thanks. ohh man. Was I was thinking.!! – P.... Feb 20 '18 at 12:37

score 0 · Answer 2 · answered Feb 20 '18 at 10:11

0

Try this

#!/bin/bash

for pid in $( ps -e | grep -v 'PID' | cut -f 2 -d ' ' );
do
    for _pid in $( cat $1 );
    do
        if [ $_pid = $pid ];
        then
            echo $pid
        fi
    done
done

Usage: ./check_if_is_active.sh list_of_pid_to_check.txt

answered Feb 20 '18 at 10:11

Kerkouch

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1

https://mywiki.wooledge.org/DontReadLinesWithFor – tripleee Feb 20 '18 at 10:23

How to check if Process is active from a file which contains list of PID?

2 Answers2