SED Command

FIND AND REPLACE with SED

Let us start off simple:

Imagine you have a large file ( txt, php, html, anything ) and you want to replace all the words

"ugly" with "beautiful" because you just met your old friend Sue again and she/he is coming over

for a visit.

This is the command:

CODE

$ sed ­i 's/ugly/beautiful/g' /home/bruno/old­friends/sue.txt

Well, that command speaks for itself "sed" edits "­i in place ( on the spot ) and replaces the word

"ugly with "beautiful" in the file "/home/bruno/old­friends/sue.txt"

Now, here comes the real magic:

Imagine you have a whole lot of files in a directory ( all about Sue ) and you want the same

command to do all those files in one go because she/he is standing right at the door . .

Remember the find command ? We will combine the two:

CODE

$ find /home/bruno/old­friends ­type f ­exec sed ­i 's/ugly/beautiful/g' {} \;

Sure in combination with the find command you can do all kind of nice tricks, even if you don't

remember where the files are located !

Aditionally I did find a little script on the net for if you often have to find and replace multiple files

at once:

CODE

#!/bin/bash

    for fl in *.php; do

    mv $fl $fl.old

    sed 's/FINDSTRING/REPLACESTRING/g' $fl.old > $fl

    rm ­f $fl.old

    done

just replace the "*.php", "FINDSTRING" and "REPLACESTRING" make it executable and you

are set.

I changed a www address in 183 .html files in one go with this little script . . . but note that you

have to use "escape­signs" ( \ ) if there are slashes in the text you want to replace, so as an

example: 's/www.search.yahoo.com\/images/www.google.com\/linux/g' to change

www.search.yahoo.com/images to www.google.com/linux

For the lovers of perl I also found this one:

CODE

# perl ­e "s/old_string/new_string/g;" ­pi.save $(find DirectoryName ­type f)

But it leaves "traces", e.g it backs up the old file with a .save extension . . . so is not really effective

when Sue comes around ;­/