For example, in some tools, you might search "id=([0-9])+" then in the replacement string you could use \1 to refer to whatever number matched the expression in the parentheses.

Regular expressions (both basic and extended), in fact, are said to be greedy—they try to match as many characters as possible. The result of the script is written to standard output and can be ...

Regular expressions — the things you feed to programs like grep — are a bit like riding a bike. It seems impossible until you learn to do it, and then it’s easy. Part of their bad… ...

When working with regular expressions in a shell script the norm is to use grep or sed or some other external command/program. Since version 3 of bash (released in 2004) there is another option: ...