Escape PHP variable in sed command from Ruby script - php

Question

I have a Ruby script that generates a sed command to replace some PHP code. The command is later executed via SSH.
command = "sed -i \"s*#{find_what}*#{replace_with}*\" #{file} "
The replace_with string will contain multiple lines of PHP code so the following escaping needs to take place:
command.gsub!(/\n/, '\\\n ') # Handle new-line escaping
command.gsub!(/&/, '\\\&') # Handle RegEx variable escaping
command.gsub!(/(\$[a-zA-Z0-9_]+)/) { |s| s.gsub!(/\$/, '\\$') } # Handle bash variable escaping
The command after escaping looks like this:
sed -i "s*require_once('file.php');*\n require_once(\$www_dir . \$path . '/file.php');\n *" /var/www/something.php
When executing this command manually everything works as expected. However if I execute the command via Kernel.system all the PHP variables are stripped out in the replacement string. Something.php ends up looking like this:
require_once( . . '/file.php');
Any ideas would be appreciated.
Thanks.

Answer 1

Update: try having single quotes around the sed command that way no bash variable substitution will be run. I'd try the ruby stuff out like this until it looks just right.
puts `echo #{command}`
If you're using SSH anyway, I'd just cook something up like this to be able to run it locally via ssh, makes it super easy to have total control by keeping it all ruby.
require 'net/sftp'
Net::SFTP.start('host', 'username', :password => 'password') do |sftp|
filedata = sftp.file.open("/path/to/remote", "r").read
filedata.gsub!(/foo/, "bar")
sftp.file.open("/path/to/remote", "w") do |f|
f.puts filedata
end
end
see http://net-ssh.rubyforge.org/sftp/v2/api/