Mastering Linux Shell Scripting - Second Edition

Other advanced features

These are some of the extra features that we can include with the double brackets. Even if we lose portability in using them, there are some great features that overcome the loss. Remember that if we only use bash, then we can use the double brackets but can't run our scripts in the Bourne shell. The advanced features that we gain, which are covered in the following sections, include pattern matching and regular expressions.