sed -i .bak ‘/^\$config_file = .*dev\/config.php”;$/ {
s_.*_//&_
a\
$config_file = “dev/config.php”;
}’ *.php

A few notes: This uses pattern matching to only apply a block of commands to lines matching a particular pattern. So on lines that match the $config_file pattern, we do the substitution. Note that since we already know the line is the correct line, the actual search & replace pattern is much simpler: .* is the string to search. We can use & to represent the entirety of the match (the entire line). Also, although it’s typical to use / as the delimiter for the s command, you can pick almost any other character. Here, I’ve used _ to avoid having to escape the //. For the newline problem, we use the a\ command to explicitly add a new line to the output stream.

Voila, \n issue resolved.

Cheers.

/usr/bin/sed is the BSD version from May 10, 2005

Optionally, you can install gnu sed or gsed via ports (currently 4.2.1 from June 2009) that behaves as you are accustomed to on linux.

$ echo “a b c d” | gsed ‘s/ /\n/g’
a
b
c
d

you need to set the “deny duplicates;” statement in the dhcpd.conf configuration file.