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Accepted
Eureka Ikara
Asked: 2012-01-07 16:00:50 +0800 CST

How to return multiline from remote SSH command

  • 772

I have a script that backs-up remote systems, and want it to display disk space on the remote backup device prior and post running backup script.

Thanks to another post have learnt how to run remote commands via SSH such as (SSH keys have been setup for auto login).

echo `ssh -t user@host uname -a`

However, how can I get a multi line response that comes from a command such as

echo `ssh -t user@host df`

Response just shows the last line of output from df

ssh remote

4 Answers

  1. Best Answer

    That sounds overly complicated way to SSH somewhere and call a command.
    Just type:

    ssh user@host df

    Voila. :)

    Edit 1
    Example of remote output parsing:

    ssh user@host df -P | tail -n +2 | awk '{print $6 "," $4}'

    Outputs comma separated list of mountpoint,availablespace like:

    /,1393276
/usr,3524132
/var,2560004
    • 7

  2. This may not be the most efficient or elegant way, but how about something like:

    REMOTEDF="ssh username@hostname df"

    echo "Pre-backup df from hostname"
    echo date >> $HOME/df-backups.out
    echo "" >> $HOME/df-backups.out
    $REMOTEDF >> $HOME/df-backups.out
    echo "" >> $HOME/df-backups.out

    --perform your backup--

    echo "Backup of hostname is complete; post-backup df:"
    echo date >>
    $HOME/df-backups.out
    echo "" >> $HOME/df-backups.out
    $REMOTEDF >> $HOME/df-backups.out
    echo "" >> $HOME/df-backups.out

    • 1

  3. here echo is the source of trouble. Remove the echo and you will get mutiline output. Why not just do ssh username@hostname cmd Why -t ?

    • 0

  4. Here's my hacky solution. This code is not perfect and I'm sure that there are other elegant and efficient methods than this. But here goes.

    I'm going to create a cmds.txt file with the input commands to run on the remote server and the output from the remote server will be saved in another file out.txt.

    By separating the input command in a separate file, it will become easier to modify code.

    Also, saving the output to a text file, will preserve the output by preserving line breaks; Helpful when we need to fetch multi-line output from the remote server.

    Contents of cmds.txt

    Code placed here will be executed in remote server
    df

    Contents of script.sh

    This runs in the local machine
    #!/bin/bash
cmd=$(cat cmds.txt)
/usr/bin/ssh -o StrictHostKeyChecking=no ssh -i $KEY $USERNAME@$HOST "$cmd" > out.txt


cat out.txt
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