Use ( .. ) to group conditions SH-1026

[ .. ] 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.

Problematic code:

[[ [ a || b ] && c ]]
[ [ a -o b ] -a c ]]

Correct code:

[[ ( a || b ) && c ]]
[ \( a -o b \) -a c ]]  # or  { [ a ] || [ b ]; } && [ c ]