(..)around test command to avoid subshell overhead.
([ "$x" -gt 0 ]) && foo
[ "$x" -gt 0 ] && foo
You are wrapping a single test command in
(..), creating an unnecessary subshell. This serves no purpose, but is significantly slower:
$ i=0; time while ( [ "$i" -lt 10000 ] ); do i=$((i+1)); done real 0m6.998s user 0m3.453s sys 0m3.464s $ i=0; time while [ "$i" -lt 10000 ]; do i=$((i+1)); done real 0m0.055s user 0m0.054s sys 0m0.001s
Just delete the surrounding
(..) since they serve no purpose and only slows the script down.
This issue only affects performance, not correctness, and can be ignored for stylistic reasons.
ShellCheck is a static analysis tool for shell scripts. This page is part of its documentation.