Global Regular Expression Print is the rather un-catchy full name of grep, the staple of any Linux users toolkit. It is a search tool run from the command line that is evolved directly from Unix, and is so useful it deserved a post of its own.

There is a classic bit of computer wisdom that states “If you’ve got a problem, and decide to solve it with regular expressions, now you’ve got two problems.” This of course stems from the perception that regular expressions are a complicated mix of magic characters and Voodoo.

Using UNIX® in a day-to-day office setting doesn't have to be clumsy. Learn some of the many ways, both simple and complex, to use the power of the UNIX shell and available system tools to greatly increase your productivity in the office.

The grep search utility is one of the most essential building blocks of command line text filtering and processing. In this tutorial, we will give you a few simple examples.

There are search tools and then there are SEARCH TOOLS. Any Linux user that has ever needed real power for their searches generally has to resort to the command line. But what if you could have a GUI tool that could also handle regular expressions?

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: bash's built-in regular expression comparison operator "=~".

This article covers two beneficial Linux tools, grep and sed. If searching for or handling text, grep and sed can increase your efficiency with Linux bash scripting and configuration files. We'll learn how to use these commands and get some helpful tips, too.

Seriously the command line does it for me, gets me all hot and bothered ;). I just love having all the tools (including the shell itself) to be able to do what I need to do.

Here's a brief example of applying a regex, drawn from the UNIX command-line utility grep, which searches for a specified pattern among the content of one or more UNIX text files. The command grep -i -E '^Bat' searches for the sequence beginning-of-line (indicated with the caret, [^]), followed immediately by upper- or lowercase letters b, a, and t (the -i option ignores case in pattern matches, so B and b are equivalent, for instance). Hence, given the file heroes.txt: