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pid=$(pgrep 'engrampa') #Get the PID of the engrampa processes .
killpid=$(echo $pid | head -1) #Get only the first line of the $pid variable and put into a new variable called $killpid.
kill $killpid

I want to maintain only the first line of the variable $pid.

Let's say I have 3 instances of the engrampa process open.

When I run the commands above step by step at terminal, I get exactly what I want: 2590

https://i.stack.imgur.com/L3U2g.jpg

When I run those exaclty commands in a script I get this result: 2590 18425 18449

https://i.stack.imgur.com/RuGX9.jpg

Why is that happening?

Lucas Rizzini
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1 Answers1

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Edit: Identified my problem thanks to steeldriver comment.

Running echo $pid | head -1 in bash do nothing. Running the same command at zsh shell I get exactly what I want.

bash shell output -> 2590 18425 18449

zsh shell output -> 2590

That being stated, my problem has been solved changing the shell of the script to #!/bin/zsh.

Edit: Another solution, and more suitable, is just using echo $pid | awk '{print $1}' instead echo $pid | head -1. It works on both shell. Thanks to Christopher comment.

Lucas Rizzini
  • 101
  • 9
  • Your original version would have worked in bash if you'd quoted the variable: echo "$pid" | head -1. However you might want to consider using pgrep -n or pgrep -o (or pidof with the -s switch) so as to avoid piping to head altogether. – steeldriver Dec 18 '18 at 01:16