I recently came across a typo that existed in a bunch of html files on my web server. I thought it should be easy enough to change, but since it was in a number of files, editing it by hand would be time consuming. Fortunately, there is an easy, one liner command to replace the text in multiple files in a sub directory using recursion.

grep -lr -e '<oldword>' * | xargs sed -i 's/<oldword>/<newword>/g'

This command broken down:

• grep for the word in a files, use recursion (to find files in sub directories), and list only file matches
• | xargs passes the results from the grep command to sed
• sed -i uses a regular expression (regex) to evaluate the change: s (search) / search word / target word / g (global replace)

For more information, see man pages for grep, sed, and xarg. Also it is very handy to learn about regular expressions as they are a valuable tool to any command line programmer!

Update 2009/7/19:

Thanks to reader btr we have a great one-line perl command that will perform the same task:

Perl provides a really nice one-line for this kind of thing:

perl -p -i -e ’s///g’ *

It also provides the option of creating a backup of each file changed:

perl -p -i.bak -e ’s///g’ *

mnemonic: PIE (”easy as pie”, etc.)
google “perl pie” and you’ll get lots of info for other uses of this technique.

http://www.linux.org/lessons/short/perlpie/perl_pie.html