How to use bash $(awk) in single ssh-command?

Question

I am trying to execute a single command over ssh that contains `sub-code` or $(sub-code) (I use it all the time but I don't know the official name for that) to be executed first, but on the target server.

For the sake of argument, let's say this is the command I want to use. Ofcourse this can be done with hostname, but this is just a simplified example that contains all the formatting wizardry I want to use.

echo `uname -a | awk '{print $2}'` 

No problem. But how do you escape this properly to send it over ssh in a single command? The following is wrong, because it lets the server reply your local hostname. The sub-code is executed locally:

ssh myServer echo `uname -a | awk '{print $2}'` 

But any escape-ishness that comes to mind doesn't work:

$ ssh myServer echo \`uname -a | awk '{print $2}'\` awk: cmd. line:1: {print $2}` awk: cmd. line:1:           ^ invalid char '`' in expression $ ssh myServer echo \$(uname -a | awk '{print $2}') bash: syntax error near unexpected token `(' $ ssh myServer echo \$\(uname -a | awk '{print $2}') bash: syntax error near unexpected token `)' $ ssh myServer echo \$\(uname -a | awk '{print $2}'\) awk: cmd. line:1: {print $2}) awk: cmd. line:1:           ^ syntax error bash: -c: line 0: unexpected EOF while looking for matching `)' bash: -c: line 1: syntax error: unexpected end of file 

I would like an answer that includes using properly escaped ` or $() because I'd like to know if it's possible.echo` could be something more complicated.

Answer 1

Try this

ssh myServer "uname -a | awk '{print \$2}' " 

Use the double quotes " in order to group the commands you will execute remotely.

You also need to escape the $ in the $2 argument, so that it is not calculated locally, but passed on to awk remotely.

Edit:

If you want to include the $( ), you again have to escape the $ symbol, like this:

ssh myServer "echo \$(uname -a | awk '{print \$2}') " 

You can also escape the backtick `, like this:

ssh myServer "echo \`uname -a | awk '{print \$2}'\` " 

Answer 2

It is better to use a heredoc with ssh to avoid escaping quotes everywhere in a more complex command:

ssh -T myServer <<-'EOF' uname -a | awk '{print $2}' exit EOF