Function expand ssh execution

Bud Spencer

4/16/24, 10:43 PM

As part of a script which runs on another (backup) server I'm trying to write a function which executes random commands remotely via ssh. To keep things simple, I want to keep the existing code mostly as is.

An example what I'm trying to do:

function NC_SSH_CMD () {
   cmdArgs=("$@")
   ssh -i [email protected] "bash -s" < ${cmdArgs[@]}
}

NC_SSH_CMD sudo -u "${webserverUser}" php ${nextcloudFileDir}/occ maintenance:mode --on

Basically, I want to use NC_SSH_CMD as a prefix for commands which should be run remotely via ssh. Thus the arguments passed should be treated as a remote command with arguments. Though my usage of cmdArgs as an array is the wrong way. It throws the error:

${cmdArgs[@]}: ambiguous redirect

What's the correct way to pass the command to the function and execute it?

Edit:

There was a bug with the command itself which was unrelated to the question. Since the error was unintuitive I didn't catch it. This works. But is there a better way to handle passing the string to the command?

function NC_SSH_CMD () {
   $(ssh [email protected]  "$*")
}

1 + 0

bash

Score:1

Ubuntu

steeldriver

4/16/24, 11:48 PM

The < operator redirects the contents of a file via standard input. To redirect a string in bash you'd use a here string:

function NC_SSH_CMD () {
   cmdArgs=("$@")
   ssh -i path/to/identityfile [email protected] "bash -s" <<< "${cmdArgs[@]}"
}

Remember to quote the array expansion ${cmdArgs[@]} else its elements will be subject to word splitting and possible filename generation.

Note that unless ${cmdArgs[@]} needs to be run in a bash shell specifically, and you know that the remote root shell is something other than bash, you may as well omit the bash -s and pass the expanded argument list directly to the default remote shell, as you discovered. However you should use "${cmdArgs[@]}" (or "$@") in place of "$*" since the latter concatenates the arguments to a single string instead of passing them separately:

function NC_SSH_CMD () {
   ssh -i path/to/identityfile [email protected] "$@"
}

+ 0

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Function expand ssh execution

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