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I need a help with a bash script that connect to server as root, execute some commands and then exit from the server.

I tried this script but when login login to server performed the command not running !

#!/bin/bash

sudo ssh -o ConnectTimeout=10 $1 'exit'

if [ $? != 0 ]; then
        echo "Could not connect to $1 , script stopped"
        exit
fi

sudo ssh $1

echo "SRV=`cat /etc/puppet/puppet.conf | grep -i srv_domain | awk '{print $3}'`"
echo $SRV
echo "puppetMaster=`host -t srv _x-puppet._tcp.$SRV | head -1 | awk '{print $8}' | cut -f1 -d"."`"
echo $puppetMaster
'exit'
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  • BTW, you'd do a lot better with a ControlMaster setup -- that way you could use one persistent SSH connection for both the test and the actual commands later, instead of assuming that if the test SSH connection works then the real one will (and paying authentication/connection/startup costs twice). Commented Mar 13, 2015 at 15:23

3 Answers 3

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I'm surprised nobody has suggested a heredoc yet.

sudo ssh "$1" <<'EOF'
SRV=`cat /etc/puppet/puppet.conf | grep -i srv_domain | awk '{print $3}'`
echo $SRV
echo "puppetMaster=`host -t srv _x-puppet._tcp.$SRV | head -1 | awk '{print $8}' | cut -f1 -d"."`"
echo $puppetMaster
EOF

This feeds everything from the <<'EOF' until the line starting with EOF into the stdin of ssh, to be received and run by the remote shell.

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3 Comments

After EOF when I am trying to ssh to $puppetMaster, but it;s not working because the value of the $puppetMaster is empty ! Why ? How can I fix it ?
puppetMaster is set inside the remote shell (the shell running on the other side of the ssh connection, which exits at the EOF). The local shell knows nothing about it. Collecting variables from a remote shell into a local shell is somewhat complex to do in a safe and secure manner; I'd suggest asking about it as a separate question.
...well -- collecting more than one from a single SSH session. If you wanted to collect only one variable per ssh call, that would be easy: puppetMaster=$(ssh "$1" <<'EOF' host -t srv "_x-puppet._tcp.$(cat /etc/puppet/puppet.conf | grep -i srv_domain | awk '{print $3}')" | head -1 | awk '{print $8}' | cut -f1 -d"." EOF
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The commands following ssh machine in a script are not run on the machine. They will be run on the local machine once the ssh exits.

Either specify the commands to run as an argument of ssh, or alternatively, run ssh and make it read the commands from standard input, and send the commands to it.

ssh machine ls
# or
echo ls | ssh machine
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0

You seem to be a little confused as to what runs where.

ssh -o ConnectTimeout=10 $1 'exit'

will connect to $1, run exit, and disconnect. 

ssh -o ConnectTimeout=10 $1 'echo hello world'

will print hello world on the server and then disconnect.

ssh $1

will open up a shell on the remote. After the shell has ended, the following commands will run locally.

echo "SRV=`cat /etc/puppet/puppet.conf | grep -i srv_domain | awk '{print $3}'`"
echo $SRV
echo "puppetMaster=`host -t srv _x-puppet._tcp.$SRV | head -1 | awk '{print $8}' | cut -f1 -d"."`"
echo $puppetMaster
'exit'

What you probably want is start bash on the remote and forward to it the commands you want to give it via stdin.

echo "my commands" | ssh $1 bash

Technically, you don't need that bash -- ssh will start bash even without it (but with different rc files).

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