How to set variable to output of a command in a bash script, without the command output showing in terminal?

Question

Trying to run the following script:

echo "Is autofs Enabled?" cmd=`systemctl is-enabled autofs` echo $cmd if [[ $cmd = "enabled" ]]; then echo "Yes autofs is enabled" elif [[ $cmd = "disabled" ]]; then echo "No autofs is disabled" else echo "Autofs not found" fi 

If autofs is not installed, script results in:

Failed to issue method call: No such file or directory Autofs not found 

Expected output of script if autofs is not installed:

Autofs not found 

How do I change the script to not print "Failed to issue method call: No such file or directory"?

Edit:Thanks everyone. Answers were exactly what I was looking for.

Answer 1

How about redirect the error stream to /dev/null?

[ $(systemctl is-enabled autos 2>/dev/null) = "enabled" ] && echo true || echo false 

On a side note using backticks while assigning the output to a variable is lowest common denominator for shell portability modern shells recommend migrating to assigning variables from commands to $()

Answer 2

You can examine the message (stdout) produced by systemctl as well as its exit status (the latter via the $? shell variable). The error message you seek to avoid is delivered to stderr, so you need to redirect that stream if you want to suppress it. Non-zero exit status can indicate either that the device was not found or that it was disabled (see the manual for more information).

#!/bin/bash -l service=$1 echo "Is $service enabled?" msg=$(systemctl is-enabled "$service" 2>/dev/null) # capture message res=$? # capture exit code if [ -z "$msg" ]; then # message is empty if service not found echo "$service not found" else # service could be enabled, disabled, static, etc. if [ "$res" -eq 0 ]; then # enabled echo "Yes $service is enabled: $msg" else echo "No, $service is disabled" fi fi 

Saving that script as tmp.sh, you can test with various inputs:

$ ./tmp.sh autofs Is autofs enabled? Autofs not found $ ./tmp.sh anacron.timer Is anacron.timer enabled? Yes anacron.timer is enabled: enabled $ ./tmp.sh runlevel6.target Is runlevel6.target enabled? No, runlevel6.target is disabled 

Given the variety of other cases, you might be better off using a case statement for more granular handling of the status, e.g.,

case "$msg" in enabled*) echo "Yes $service is enabled" ;; disabled) echo "No, $service is disabled" ;; linked*) # etc.. ;; static*) # etc.. ;; esac