Something along these lines would allow using bash without making your script completely broken: #!/bin/sh if [ -z "$BASH_VERSION" ]; then if w

Something along these lines would allow using bash without making your script completely broken: #!/bin/sh if [ -z "$BASH_VERSION" ]; then if which bash >/dev/null 2>/dev/null; then exec bash "$0" else echo "ERROR: bash was not in your PATH" >&2 exit 1 fi fi # now start using bash-only shortcuts safely if [[ "hello" == "hello" ]]; then echo Bash has been achieved. fi I'm not promising that's completely foolproof (it clearly isn't), but it works with the default Ubuntu 13.10 config of having /bin/sh linked to /bin/dash. And you could easily expand on the idea to look in specific locations for the bash binary even if it's not in the path, check those binary's versions, etc.