Consistent use of Bash-style compound commands (i.e. [[) instead of the [ builtin
Test to verify logic is preserved:
bash$ f() { if [[ $# -eq 0 || "$1" != "-q" ]] ; then echo IF; else echo ELSE; fi; }; f; f -z; f -q
IF
IF
ELSE
Remove superfluous use of quotes in Bash script hacking/env-setup
Prefer modern-style Bash command substitution in hacking/env-setup
Corrected quoting of parameter expansions in hacking/env-setup