Can I pass a variable from case statement out of SSH session?

Question

Let's say there is a case statement within the SSH session. I want to pass the variable entry out of remote machine and store it in local machine's csv file.
The example:

#!/bin/sh
set -x
    
read -p 'Enter the raspberry ip address you want to connect:' Rasp_id
entry=$(sshpass -pthe@Donut ssh -oStrictHostKeyChecking=no pi@"$Rasp_id" "$(cat << 'E3


    cd
    read -p 'Enter the case you want to configure\n 1.1 WM \n 2.1 LWM\n' option

    case $option in

    (1)
    read -p 'config_wide_motion token' token_w_m
    cat SoundEye/NoCAN/config_nocan.json
    cat SoundEye/NoCAN/config_processor_motion.json
    entry="1_WM"
    ;;

    (2)
    read -p 'config_laser_wide_motion token:' token_l_w_m
    cat SoundEye/NoCAN/config_nocan.json
    cat SoundEye/NoCAN/config_processor_motion.json
    entry="1_LWM"
    ;;
    esac

E3
)"
)
printf "$entry"

However, it doesn't do what I want. I would like to see the entry be either 1_WM or 1_LWM when it finished the last line

It strikes me as more useful to do the user input locally and then simply `ssh user@host cat "$somename" "$someothername"`. Also, you seem to want to cat the same files regardless of user input on the second question, and the variable read is not used. — Kusalananda, Jan 06 '21 at 09:47
What exactly do you mean by "it couldn't execute as what I want"? For one, you have the same problem as in [your other question](https://unix.stackexchange.com/q/627414/377345) regarding the mix between shell variables in your local script and your remote ssh session. — AdminBee, Jan 06 '21 at 09:49
i would like to pass the variable **entry** out of SSH session , pass the variable value either entry="1_WM" or entry="1_LWM" out of remote machine to local machine, store it to local machine CSV file. — TensorFlowGuan, Jan 06 '21 at 10:07
Always use a format string for printf: see https://github.com/koalaman/shellcheck/wiki/SC2059 — glenn jackman, Jan 06 '21 at 15:23

Stéphane Chazelas · Answer 1 · 2021-01-06T12:08:39.413

Your:

entry=$(
  sshpass...
)

Captures the output of sshpass and stores it in the $entry variable.

You're outputting the contents of SoundEye/NoCAN/config_nocan.json and SoundEye/NoCAN/config_processor_motion.json (using two invocations of the concatenating command!?), so that's what will end up in $entry.

You're not outputting the contents of the $entry variable of the remote shell (which appears to be bash as you're using that bash-specific read -p), so it won't make it to the $entry variable of the local shell.

Since you're already using structured (json) content, you might as well include that information in there and, in the remote shell, output something like:

printf '{ "type": "%s", "config_nocan": %s, "config_processor_motion": %s }\n' \
  "$entry" \
  "$(<SoundEye/NoCAN/config_nocan.json)" \
  "$(<SoundEye/NoCAN/config_processor_motion.json)"

So $entry of your local shell will have some json structured data. So you can do for instance:

type=$(printf '%s\n' "$entry" | jq -r .type)
config_nocan=$(printf '%s\n' "$entry" | jq .config_nocan)
...

In your specific case though, I'd say it would make more sense to leave all the user interactions local, and only use ssh only to transfer the information you want.

score -3 · Answer 2 · answered Jan 06 '21 at 09:47

-3

I would think this would break modern security standards. The fun way, I would create native listener on remote machine and post it a message to act on, storing your data. Or you simply use a shared disk.

answered Jan 06 '21 at 09:47

ken205726

3
1

1

In what way do you think it would break what modern security standards? How would you go about creating a native listener, and how would it be better? – ilkkachu Jan 06 '21 at 12:29

Can I pass a variable from case statement out of SSH session?

2 Answers2