Remove superfluous (..) around condition.

Problematic code:

if ([ "$x" -gt 0 ])
then true; fi

Correct code:

if [ "$x" -gt 0 ]
then true; fi

Rationale:

The shell syntax is if cmd, elif cmd, while cmd and until cmd without any parentheses. Instead, parentheses are an independent construct used to create subshells.

ShellCheck has noticed that you're wrapping (..) around one or more test commands. This is unnecessary, and the resulting fork adds quite a lot of overhead:

$ 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.

Exceptions:

None.

Related resources:

• Help by adding links to BashFAQ, StackOverflow, man pages, POSIX, etc!