executing script using ssh inside a loop

Question

I am trying to write a script, where I have a loop to login to multiple remote machines and execute a script inside each machine. Here is an example:

for ((j=1; j < 2; j++)); do 

  mchname="n"$j

  ssh -T $mchname <<'ENDSSH'    
    ./run_script < input > output &    
  ENDSSH

done

Whenever I try to execute the above script I get: "warning: here-document at line 37 delimited by end-of-file (wanted `ENDSSH')"

I am new to ssh, so I am sure I am making a silly mistake. Can anyone suggest me a solution? Thanks.

mrb · Accepted Answer · 2012-06-23 20:46:44Z

13

There's a problem in your bash script. The heredoc end tag (ENDSSH in your script) cannot be indented.

Try this instead:

  ssh -T $mchname <<'ENDSSH'    
    ./run_script < input > output &    
ENDSSH
# ^ no indentation for that line

Edit:

Also, you can run a command on the remote system by passing it as an argument to ssh, rather than providing it as standard input. The command will be executed by the user's remote shell:

ssh -T $mchname './run_script < input > output &'

answered Jun 23, 2012 at 20:46

mrb

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3 Comments

dave4420 Over a year ago

And -T is the default when you give ssh an explicit command to run, so ssh $mchname './run_script < input > output &'.

user1477337 Over a year ago

Thanks a lot! I would have never caught that!

chepner Over a year ago

If you use '<<-' instead of '<<' for the here document, any leading tabs (just tabs, not arbitrary whitespace) from the here document and the end tag will be stripped, allowing you to indent them more naturally.

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