Write SSH command over multiple lines

Question

I'm trying to remote login to a shell and execute a bunch of commands on the shell. But to make it more readable, I'd like to place my code over multiple lines. How should I be doing this?

ssh -o <Option> -x -l <user> <host> " $long_command1; $long_command2; ....  "

Thanks!

Alfe · Accepted Answer · 2015-08-19T20:37:30.410

41

ssh is in fact just passing a string to the remote host. There this string is given to a shell which is supposed to interpret it (the user's login shell, which is typically something like bash). So whatever you want to execute needs to be interpretable by that remote login shell, that's the whole rule you have to stick to.

You can indeed just use newlines within the command string:

ssh alfe@sweethome "
  ls /home/alfe/whatever
  ping foreignhost
  date
  rm foobar
"

edited Aug 19 '15 at 20:37

answered Aug 18 '15 at 21:30

Alfe

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You might want to have a look at [this answer](http://stackoverflow.com/questions/32019076/having-an-issue-passing-variables-to-subshell/32019393#32019393) I gave just recently about passing variables into ssh-remote shells. – Alfe Aug 18 '15 at 21:32

ntki · Answer 2 · 2015-08-19T20:45:16.430

28

You can use the Here Documents feature of bash. It is like:

ssh <remote-host> bash <<EOF
echo first command
echo second command
EOF

EOF marks the end of the input.

For further info: use man bash and search for Here Documents.

Edit: The only caveat is that using variables can be tricky, you have to escape the $ to protect them to be evaluated on the remote host rather then the local shell. Like \$HOSTNAME. Otherwise works with everything that is run from bash and uses stdin.

edited Aug 19 '15 at 20:45

answered Aug 18 '15 at 21:30

ntki

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is it the remote user's bash shell that'll be used here? – dspshyama Aug 18 '15 at 21:42
@ShyamaDorbala: Yes, remote bash. It actually works without `bash` as well, just "HereDocing" to ssh. – ntki Aug 18 '15 at 21:55
interesting. I'll check it out. Thanks! – dspshyama Aug 18 '15 at 22:02
I like this solution, but I wish it worked better with indentation. Leading spaces will break it (but leading tabs is OK). – Joe Coder Dec 05 '19 at 23:42
1

As an alternative to the escaping, you can use <<"EOF" to stop the evaluation in the local shell. – siwyd Jan 14 '21 at 12:35

score 2 · Answer 3 · answered Aug 18 '15 at 21:30

2

You can do like in the following example.

ssh -o <Option> -x -l <user> <host> '
pwd
whoami
ls
echo "$PATH"
'

answered Aug 18 '15 at 21:30

crafter

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Write SSH command over multiple lines

3 Answers3

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