The following code will perform a global search and replace in UNIX.

perl -p -i -e 's/oldstring/newstring/g' $(find . -name \*.fileext)

The parameters mean the following:

• -p = assume loop like -n but print line also, like sed (-n = assume "while () { ... }" loop around program)
• -i = edit files in place
• -e = precedes each line of the program (in this case 's/oldstring/newstring/g')
• $(find . -name \*.fileext) = do this for all file names matching *.fileext in the current drectory