Processing while read line remotely via ssh doesn't fill read variable

Question

I'm trying to remotely process a while read line loop via ssh with the following:

ssh /root/.ssh/id_rsa "while read var; do echo \"- $var -\"; done < /tmp/file; cat /tmp/file"

/tmp/file exists remotely. Output of the command should be:

- /tmp -
- /var -
/tmp
/var

But output actually is:

- -
- -
/tmp
/var

Why doesn't $var get filled here when remotely executed ? If I happen to connect a console via ssh to the machine and execute the same command, it works as expected.

Answer 1

$var is getting expanded before the ssh because it's inside double quotes. If you make the command you're passing to ssh be in single quotes it won't get expanded, or if you escape the $ you should be set:

ssh /root/.ssh/id_rsa 'while read var; do echo "- $var -"; done < /tmp/file; cat /tmp/file'

or

ssh /root/.ssh/id_rsa "while read var; do echo \"- \$var -\"; done < /tmp/file; cat /tmp/file"

Answer 2

You should use single quotes or escape the $ in $var. Right now $var is getting substituted before ssh runs.

ssh /root/.ssh/id_rsa 'while read var; do echo "- $var -"; done < /tmp/file; cat /tmp/file'