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:

One of the things you may find you want to do often from your command line is to view the contents of a text file. This could be to view the contents of some startup script or just one of your own basic configuration files like .bashrc or .bash_aliases. The command is simple to use.

units is a command-line tool which performs units conversion between various scales. units is the perfect tool for engineer or scientific workstation, you can call it either interactively from the prompt or within command line. It already handles more than two thousand units and this can be enhanced with your own units in a separate data file.

Perl one-liners are small and awesome Perl programs that fit in a single line of code and they do one thing really well.

Learn how to use the Linux command line and some basic Bash scripting techniques to draw lines and text on images using ImageMagick. And create a pixel ruler along the way.

I just finished writing my third e-book about Perl one-liners. Perl one-liners are small and awesome Perl programs that fit in a single line of code and they do one thing really well. These things include changing line spacing, numbering lines, doing calculations, converting and substituting text, deleting and printing certain lines, parsing logs, editing files in-place, and many more.

Why text files, specifically? Well, if you're doing much work at the shell on Linux, you'll start encountering a lot of text or files that can behave like text. Log files, configuration files and output from many commands can all be manipulated with the GNU textutils.

In today's post I'm going to show how to use the command line find program to search for files. There are certainly different GUI tools available in Linux, such as Beagle, to search for files. The advantage of many of these systems is that they index the files on your system so that the searching is rather fast.

Today I'm going to show you how to use the head and tail commands to view portions of text files. There are, of course, other commands that can be used to view text files. The cat command can be useful for viewing small text files while more and less can be good for larger files. But what if you're only interested in just the beginning or the end of a file? That's where head and tail come in.