bash if statement prints stuff to terminal

2022-05-04 10:22 Lev Shapiro imported from Stackoverflow

I am new to writing bash scripts, so I can't understand how to fix (remove) consoling of stuff that are inside if statement (see code below). Could someone tell me why it does stuff like that?

    if pgrep "Electron" -n
        then 
            killall Electron
        else        
            echo "Visual Studio Code is already closed"
    fi

2 answers

answered 2022-05-04 10:50 Tolis Gerodimos
You could bash redirection https://www.gnu.org/software/bash/manual/html_node/Redirections.html
```
if pgrep "Electron" -n > /dev/null
        then 
            killall Electron 
        else        
            echo "Visual Studio Code is already closed" 
    fi
```
When you pass a linux command in the if statement, bash will run this command in order to check its exit code. The exit code of this command will be used in order to decide true or false. In bash 0 means true, any other exit code evaluates to false.

So since bash execute the command, you will see its output in the terminal. In order to surpress the output, you can use redirection
answered 2022-05-04 10:51 Czaporka
From man pgrep on MacOS:

-q Do not write anything to standard output.

So you can change your condition to:
```
if pgrep -q "Electron" -n
    ...
```
A more generic solution that should work with implementations of pgrep that do not support the -q option (e.g. on Ubuntu), as well as with any other tool, would be to redirect the process's standard output to /dev/null:
```
if pgrep "Electron" -n >/dev/null
    ...
```

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bash if statement prints stuff to terminal

2 answers

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