Pattern: Unescaped ( or ) in [..]
Issue: -
[ is implemented as a regular command, so ( is not special.
The preferred way is not to group inside [ .. ] and instead compose multiple [ .. ] statements using the shell's &&, || and { ..; } syntax, since this is well defined by POSIX.
Some shells, such as Bash, support grouping with \( .. \), but this is an obsolete XSI-only extension.
Example of incorrect code:
[ -e ~/.bashrc -a ( -x /bin/dash -o -x /bin/ash ) ]Example of correct code:
In POSIX:
[ -e ~/.bashrc ] && { [ -x /bin/dash ] || [ -x /bin/ash ]; }Obsolete XSI syntax:
[ -e ~/.bashrc -a \( -x /bin/dash -o -x /bin/ash \) ]