Execute bash command with calling subshell $() via ssh with Here Document

Question

I try to send command via ssh which looks like this:

ssh user@192.168.1.1 "echo $(uname -a)"

But my problem is, that $(uname -a) part actually create a subshell and executes not on 192.168.1.1 server, but on my system, from which I executed this command.

How can I fix it?

P.S. My actual example involved docker stop all command, which looks like

docker stop $(docker ps -q)

but I simplified question.

UPDATED: Sorry, I oversimplify my question. My command use Here Document (because inside command is complex and use a lot of different quotes marks)

ssh user@192.168.1.1 <<SSHCOMMAND
  echo $(uname -a)
SSHCOMMAND

So Ignacio Vazquez-Abrams solution will not work

score 7 · Answer 1 · answered Sep 11 '15 at 12:25

7

Single quotes suppress all substitution.

ssh user@192.168.1.1 'echo $(uname -a)'

answered Sep 11 '15 at 12:25

Ignacio Vazquez-Abrams

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Thank you, your solution works fine, but I added more complex example, which is closer to my actual command. – ShockwaveNN Sep 11 '15 at 12:35

score 6 · Accepted Answer · edited Apr 13 '17 at 12:13

6

I found solution -

ssh user@192.168.1.1 <<'SSHCOMMAND'
  echo $(uname -a)
SSHCOMMAND

Pretty strange for me, but works, thanks Ignacio Vazquez-Abrams for correct name of this process 'substitution', I couldn't find before :)

edited Apr 13 '17 at 12:13

Community

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1

answered Sep 11 '15 at 12:42

ShockwaveNN

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See 'man sh' near the bottom of the section 'Redirections'. It is all documented there. – m4r35n357 Nov 14 '20 at 15:41

Execute bash command with calling subshell $() via ssh with Here Document

2 Answers2