hoopajoo.net | Modifying lots of files

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If you have some changes to do to a lot of files, for example you're moving a section of your website and all cgi-bin links need to become shoppingcart instead, perl can do it easy and make backups for you. In bash you might do something like this:

#!/bin/bash

for FILE in *.html
do
 mv $FILE $FILE.backup
 sed s/cgi-bin/shoppingcart/g $FILE.backup > $FILE
done

But in perl, using the -p switch to do the printing while() loop and the -i switch to instruct perl to edit in place. The whole script above could be done like this as a one-liner in perl:

perl -pi.backup -e 's/cgi-bin/shoppingcart/g' *.html

The -i tells perl to basically move the file to the .extension you specify, and anything printed will go to the original name. The -p means loop over the file and print anything in $_, and -e means execute this code in the while loop. So you basically do the s/// operator then it prints out the changes, and even preserves a .backup file for you!