TODO: Easily available on google
'''Sed''' is an extremely handy commandline *nix tool. Refer to its manual page for a more extensive overview of its capabilities.
=Uses=
==Substitution==
The most popular command of sed is the <code>s</code> command for substitution. To use the command, type an s, followed by a delimiting character, followed by a regular expression to look for, followed by the delimiting character, followed by an expression with which to replace what was found, followed by a final delimiting character. (<code>/</code> is the conventional delimiting character and potentially required by some versions of sed. GNU sed can take any character however, and when URLs or paths are involved, <code>%</code> is often a handy choice to lessen the amount of escaping required.)
<pre>
$ echo "Never let schooling interfere with your education." | sed 's/schooling/video games/'
Never let video games interfere with your education.
</pre>
Groups can be useful in the replacement portion. Use the <code>-r</code> flag if you don't want to escape the initial grouping parenthesis. The <code>-e</code> flag allows for multiple expressions to be evaluated.
<pre>
$ echo "Never let schooling interfere with your education." | sed -re 's/(schooling)/costly \1/' -e 's/(education)/invaluable \1/'
Never let costly schooling interfere with your invaluable education.
</pre>
=Examples=
* [[Reencoding MediaWiki pages#Script]]
* [[Central Authentication System#Scripted Login]]
[[Category:Commandline *nix]]
[[Category:Pending deletion]]