CODEWITHSUNDEEP
linuxbashshell
yoon
yoon

Reputation: 1385

How can I store a remote server variable to local server variable with ssh?

I'm making a bash script that exits if the remote server has a specific file and specific contents.
I check the file with the code below:

ssh $DEPLOY_HOST 'VAR=false

if [ -f /filename ]; then
    . /filename
    REMOTEID=$ID
        if [ "$REMOTEID" == "something" ]; then
                VAR=true
        fi
else
    echo "Missing /filename"
fi

if [ "$VAR" == false ]; then
    exit 1
fi
'

But that exit command doesn't work for local server, so the afterward code is executed, which I don't expect.
I think I have to get the result variable(VAR) from the remote server so that the local server can decide whether to exit or not with the variable.
How can I solve this?
Thanks :)

Upvotes: 1

Views: 604

Answers (1)

rtx13
rtx13

Reputation: 2610

Try this:

ssh $REMOTE 'test -e file' && exit

where file is the name of the file on the REMOTE server that you want to check for existence.

The exit code from the test command on the REMOTE server will be passed through ssh's exit code into your local shell and be used with the && operator.

If you need to return the string value of a variable, you could use this pattern:

VAR=$(ssh $REMOTE '
{
    some command
    some other command
    ...
    # all of the stdout from these commands will be discarded
} > /dev/null
echo $VAR # the stdout from here will be returned as stdout from ssh
')

Let's break this down:

  • The {} block groups all commands where we want to discard stdout.
  • The '' single quotes capture all of the commands to run on the REMOTE server
  • The VAR=$(ssh ' ... ') command will take stdout from the echo $VAR and place it in the local variable named VAR.

Upvotes: 1

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