9

I'm running a GUI program called zeal(compiled from src) and add a script(zeal.sh) for the executable:

#!/bin/bash if pgrep zeal &>/dev/null; then printf "already on\n" else ~/tools/zeal/zeal/zeal &>/dev/null & fi

The strange thing is that when I run this script like /path/to/zeal.sh, it always tells "already on", while with bash /path/to/zeal.sh it correctly decides whether the process is running or not.

I also checked other GUI programs(like firefox) with similar scripts and they work fine.

So how can this happen and how to fix it?

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1
  • I've been pulling my hair out for an hour because of this pgrep issue. It felt like someone was playing with me. Unbelievable. 😓 But now I understand that it's because the script I'm trying to run is named after the executable I'm trying to match with pgrep 🤡 Commented Aug 11 at 22:04

2 Answers 2

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7

The long option --exact proposed in Hauke's answer didn't work on some systems. You can use the equivalent short option -x instead.

#!/bin/bash if pgrep -x "zeal" > /dev/null then echo "Running" else echo "Stopped" fi
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  • And if you get the error 'pgrep unary operator expected', make sure to leave the square brackets off of the 'if' statement. Common rookie mistake. :) Commented Jun 12, 2017 at 17:36
3

The problem is that the direct call makes the script name the command name, see

cat /proc/$PID/comm

That causes pgrep to match. If called via bash then the command name is "bash".

Use

pgrep --exact zeal

instead.

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1
  • The --exact flag does not work on macOS but you can use a regex pattern like this: [$]> pgrep '^zeal$' Commented Nov 30, 2022 at 3:48

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