CODEWITHSUNDEEP
bashwc
Even Tmas
Even Tmas

Reputation: 1

why the num is wrong when I use bash -x

When I count process's number to use wc -l , The number is 2 in the command line, but I found it is 4 in the shell scripts, what's happened?

$ ps -ef |grep -v grep |grep etcd  |wc -l
2

$ bash -x count.sh etcd
++ ps -ef
++ grep -v grep
++ grep etcd
++ wc -l
+ num=4
+ case $1 in
+ echo 4
4

The shell script

#!/usr/bin/env bash

num=$(ps -ef |grep -v grep |grep etcd  |wc -l)

case $1 in
etcd) 
    echo ${num}
;;

*) 
   echo  "other"

;;
esac

Upvotes: 0

Views: 53

Answers (1)

hek2mgl
hek2mgl

Reputation: 158090

I guess you are calling the script with an argument: count.sh etcd. The script itself will be part of the ps output, which does add to the results.

Use pgrep, it is meant for that

pgrep -c etcd

I further recommend to use the -x (exact match) argument, to prevent it from matching etcdctl, for example:

pgrep -xc etcd

#!/usr/bin/env bash

num=$(pgrep -xc etcd)

case $1 in
etcd) 
    echo "${num}"
;;

*) 
   echo  "other"

;;
esac

Upvotes: 1

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