fix checking for use of '--overlay-tool unionfs'

Author: boegel

.github/workflows/test_eessi_container_script.yml

@@ -138,13 +138,14 @@ jobs:
 
               # test use of --overlay-tool unionfs
               elif [[ ${{matrix.SCRIPT_TEST}} == 'unionfs' ]]; then
+                outfile=out_unionfs.txt
                 container="docker://ghcr.io/eessi/build-node:debian12"
                 export SINGULARITY_BIND="$PWD:/test"
                 echo 'ls -ld /cvmfs*/software.eessi.io/*' > test_script.sh
                 chmod u+x test_script.sh
                 ./eessi_container.sh --verbose --container ${container} --access rw --overlay-tool unionfs --mode run /test/test_script.sh 2>&1 | tee ${outfile}
                 for pattern in "/cvmfs/software.eessi.io/versions" "/cvmfs_ro/software.eessi.io/versions"; do
-                  grep "${pattern}" $outfile || (echo "Pattern '${pattern}' not found in $outfile"; exit 1)
+                  grep "${pattern}" ${outfile} || (echo "Pattern '${pattern}' not found in ${outfile}"; exit 1)
                 done
 
               else