Pattern: Malformed expression grouping in [[ .. ]] or [ .. ]
Issue: -
[ .. ] should not be used to group subexpressions inside [[ .. ]] or [ .. ] statements.
For [[ .. ]], use regular parentheses.
For [ .. ], either use escaped parentheses, or preferably rewrite the expression into multiple [ .. ] joined with &&, || and { ..; } groups. The latter is preferred because [ .. ] is undefined for more than 4 arguments in POSIX.
Example of incorrect code:
[[ [ a || b ] && c ]]
[ [ a -o b ] -a c ]]Example of correct code:
[[ ( a || b ) && c ]]
[ \( a -o b \) -a c ]] # or { [ a ] || [ b ]; } && [ c ]