File: autoconf.info,  Node: Shell Pattern Matching,  Next: Shell Substitutions,  Prev: File System Conventions,  Up: Portable Shell

11.7 Shell Pattern Matching
===========================

Nowadays portable patterns can use negated character classes like
‘[!-aeiou]’.  The older syntax ‘[^-aeiou]’ is supported by some shells
but not others; hence portable scripts should never use ‘^’ as the first
character of a bracket pattern.

   Outside the C locale, patterns like ‘[a-z]’ are problematic since
they may match characters that are not lower-case letters.