ASH/BASH in Alpine: how to expand a variable from a list of variable names read from a list file-CodePudding

I've been trying to figure out a way to expand a variable from a string (the variable name) read from a list within a file.

The objective here is to evaluate if all variables in a gitlab pipeline are present, if not, fail the pipeline.

The best possible solution would be to have this as an one-liner and working from Alpine's ash shell, but a bash -c "something something" could also do.

Clearly there's a problem with the (!) expansion character as the varcontent is always empty, but I just can't figure out what I'm doing wrong.

alpine314:~# cat checkvars.sh
#!/bin/bash
false=false
while read -r line; do
    varcontent=${!line}
    if [ -z "$varcontent" ]; then
        echo "Error: Missing a required pipeline variable."
        false=true
        exit 1
    else
        echo "$line: $varcontent"
    fi
done < $1
alpine314:~# cat varsfile
VAR1
VAR2
VAR3
alpine314:~# echo $VAR1
1
alpine314:~# echo $VAR2
2
alpine314:~# echo $VAR3

alpine314:~# bash -x checkvars.sh varsfile
  false=false
  read -r line
  varcontent=
  '[' -z '' ']'
  echo 'Error: Missing a required pipeline variable.'
Error: Missing a required pipeline variable.
  false=true
  exit 1
alpine314:~#

The desired behavior here is to exit the script with an error in case any of the variables are empty/not set.

Cheers!

CodePudding user response：

what I'm doing wrong.

Your variables are not exported. Run the following before running your scirpt.

 export VAR1 VAR2 VAR3

Check your scripts with shellcheck. false=true - would be better to use a different variable name...