Taken from http://www.davidpashley.com/articles/writing-robust-shell-scripts/

Bash_guidelines.rst

`bash set -u # The script crashes if a variable is uninitialized set -e # The script crashes if the exit code of a command is not zero`

• Use "$@" instead of $@
• Use quotes around filenames
• Use mkdir -p to create a full path
• Use rm || true to avoid a non-zero exit
• Use traps when using temporary files: `bash if [ ! -e $lockfile ]; then trap "rm -f $lockfile; exit" INT TERM EXIT touch $lockfile critical-section rm $lockfile trap - INT TERM EXIT else echo "critical-section is already running" fi`
• To avoid race conditions with lock files: `bash if ( set -o noclobber; echo "$$" > "$lockfile") 2> /dev/null; then`
• Implement rollback functions when modifying dangerous things: `bash rollback() { del_from_passwd $user if [ -e /home/$user ]; then rm -rf /home/$user fi exit } trap rollback INT TERM EXIT add_to_passwd $user cp -a /etc/skel /home/$user chown $user /home/$user -R trap - INT TERM EXIT`
• Be atomic : work on copies and if the work succeeded, copy the modified files back
• Never use [ or test, always use [[ for secure string handling
• [[ works only in Bash, Zsh and the Korn shell, and is more powerful; [ and test are available in POSIX shells
• Avoid using echo and use printf instead