Question

I’m trying to make a system call to SSH to a server and echo a string. The string is defined by ruby and has dollars signs in it.

#!/usr/bin/env ruby
string = '$$%%$#@%$#@%325dg345345'

puts %x(ssh server "echo \'#{string}\'")

When I execute, the output that comes back is not the string. The remote server is interpreting the dollar signs as variable. Is there any form of clever escaping I can do to prevent this? The characters are random, so just editing the string to escape the dollar signs will not work.

Answer 1

You can use the stdlib’s Shellwords library to escape not only the dollar signs, but also spaces and any other “dangerous” characters your string might have:

require 'shellwords'

string = '$$%%$#@%$#@%325dg345345'
escaped_string = Shellwords.escape(string)
# "\\$\\$\\%\\%\\$\\\#@\\%\\$\\\#@\\%325dg345345"

puts %x(ssh server "echo #{string}")