local variable is not accesible inside ssh block

Question

#!/bin/sh
flag="False"
ssh -n  $Domain_1@$IP "$( cat <<'EOT'
$flag="True"
cat << 'EOT'
)"

flag is equal to false before connecting to the remote location.I just want to change the value of flag inside the ssh block after doing some operation in remote location and return the value of flag to my local variable flag. –

Your code doesnt make any sense the way it is. What exactly are you trying to accomplish? — D. Ben Knoble, Jun 02 '19 at 13:18
In terms of quoting, that looks ok, it's not in single quotes. Be careful, the `$(` is evaluated by the shell on the local machine, and leaving aside the missing/wrong end of your here-document, you roughly appear to be sending `False="True"` to the remote machine. Is that what you indend? — Ulrich Schwarz, Jun 02 '19 at 14:13
flag is equal to false before connecting to the remote location.I just want to change the value of flag inside the ssh block after doing some operation in remote location and return the value of flag to my local variable flag. — user355931, Jun 02 '19 at 15:38
↑ ↑ For the [possible duplicate](https://unix.stackexchange.com/q/66581/100397) I've suggested, it's not so much the "capture output" part as the "capture exit code" part — roaima, Jun 02 '19 at 15:57

score 0 · Answer 1 · answered Jun 05 '19 at 21:54

I'm assuming you are wanting to do something on the lines of

#!/bin/sh

flag=$(
    ssh -T "$user@$host" <<'END_SCRIPT'
        # some operations on
        # the remote host goes here

        # later...

        if some_condition; then
            echo true
        else
            echo false
        fi
END_SCRIPT
)

This would execute the script given as a quoted here-document on the remote host, and its output would be assigned to the local variable flag. The way I have written it here, I'm assuming that the some operations bit does not produce any output, and instead that the only output produced by the remote script comes from either one of the two conditional echo commands.

Your flag variable would be assigned the string true or false depending on the outcome of some_condition.

If you need to use the value $flag inside the remote script, you would have to use an unquoted here-document. Care must then be taken to properly escape any shell expansions that you would want to happen remotely (by escaping the $ of these as \$).

local variable is not accesible inside ssh block

1 Answers1