Search and replace with sed when dots and underscores are present

Question

How do I replace foo. with foo_ with sed simply running

sed \'s/foo./foo_/g\' file.php

doesn\'t work. Thanks!

Answer 1

Interestingly, if you want to search for and replace just the dot, you have to put the dot in a character set. Escaping just the dot alone in a sed command for some reason doesn't work. The dot is still expanded to a single character wild card.

$ bash --version  # Ubuntu Lucid (10.04)

GNU bash, version 4.1.5(1)-release (x86_64-pc-linux-gnu)

$ echo aa.bb.cc | sed s/\./-/g  # replaces all characters with dash

'--------'

$ echo aa.bb.cc | sed s/[.]/-/g  # replaces the dots with a dash

aa-bb-cc

With the addition of leading characters in the search, the escape works.

$ echo foo. | sed s/foo\./foo_/g  # works

foo_

Putting the dot in a character set of course also works.

$ echo foo. | sed s/foo[.]/foo_/g  # also works

foo_

-- Paul