Escaping $ variable in sed over ssh command?

Question

I have a command like this:

ssh user@hostname 'sed -e "s|foo|${bar}|" /home/data/base_out.sql > /home/data/out.sql'

The sed command is working in local shell. But it is not expanding the variable over ssh command. Thanks!

Answer 1

The rule is that within single quotes, parameters are not expanded. You have single quotes around the entire command.

Try this:

ssh user@hostname "sed -e 's|foo|$bar|' /home/data/base_out.sql > /home/data/out.sql"

Now $bar is expanded before the command string is passed as an argument to ssh, which is what you want.

I removed the curly braces around ${bar} because I believe they offer a false sense of security. In this case, they are not protecting you against any of the issues associated using shell variables in sed commands.