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linuxbashsshquoting

Bash resolve variables locally before used in a remote context

I've got a script that sets some environment variables on a remote machine, but I've got a problem with some variables being resolved in the remote machine's context. These variables must be resolved before being sent to the remote.

#!/bin/bash
devIP=$(ifconfig | sed -En \'s/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p')
#10.0.0.1

ssh -A ubuntu@remote '\
export variable="$devIP";\
echo $variable'
#Will echo blank as it is trying to resolve $devIP under the remote context.

How can I properly feed the script executor's IP into an environment variable on the remote machine?

Solution

  • Consider the following command

    ssh -A ubuntu@remote "\
export variable=$devIP;\
echo \$variable"

    Here variable substitution is performed on the local machine for variable $devIP in the command line argument 

    export variable=$devIP; echo \$variable

    because of the double quotes.

    Yet variable $variable is protected from local substitution with a backslash.