Next: Shell Substitutions, Previous: File System Conventions, Up: Portable Shell
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.