Pattern: Use of [] around range in tr
Issue: -
Ancient System V tr required brackets around operands, but modern implementations including POSIX, GNU, OS X and *BSD instead treat them as literals.
Unless you want to operate on literal square brackets, don't include them.
Example of incorrect code:
tr -cd '[a-z]'Example of correct code:
tr -cd 'a-z'If you do want to replace literal square brackets, reorder the expression (e.g. a-z[] to make it clear that the brackets are not special).
ShellCheck does not warn about correct usage of [..] in character and equivalence classes like [:lower:] and [=e=].