Create multiple variables from output of single ssh connection

Question

I'm working on a bash script that is currently doing the following for multiple variables:

variable1=$(ssh -T user@hostname "command one")  
variable2=$(ssh -T user@hostname "command two")  
variable3=$(ssh -T user@hostname "command three")  
variable4=$(ssh -T user@hostname "command four")

Is there an easy way (short of sticking the output of multiple commands into a single file and then working with that file) to assign multiple variables from different remote commands on a single ssh connection?

jas_raj_total · Accepted Answer · 2014-01-08 10:38:24Z

3

You can do this by executing all the commands in one SSH command and then getting the output of each back into an array.

Finally, iterate over the array and process as necessary.

Code:

#!/bin/sh

IFS=$'\n'
VARS=`ssh user@host 'echo 1 2; echo 3'`

for A_VAR in $VARS; do
    echo "Out: $A_VAR"
done

Output:

> ./sshtest.sh
Out: 1 2
Out: 3

answered Jan 8, 2014 at 10:38

jas_raj_total

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Kevin · Accepted Answer · 2013-12-25 05:30:00Z

0

No. There is no "return" in bash*, and certainly not over ssh. All you can do is pass data via stdout and stderr.

* all processes and functions have an exit value of an int between 0 and 255, and within a function you can use return to exit with a particular value, but it's not really returning anything like in any other language.

edited Dec 25, 2013 at 5:30

answered Dec 25, 2013 at 5:24

Kevin

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Comments

brianadams · Accepted Answer · 2013-12-25 06:06:56Z

0

You can get finer control over what you want by "programming the SSH library" (via wrapper). An eg, in Perl, you can use libraries such as Net:SSH::Perl.

my $ssh = Net::SSH::Perl->new("yourhost");
$ssh->login("user1", "pass1");

$ssh->cmd("foo");
$ssh->cmd("bar");

you do multiple commands via a single $ssh instance (contrary to calling the ssh command line tool multiple times using the shell). This is just an example.

answered Dec 25, 2013 at 6:06

brianadams

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