CODEWITHSUNDEEP
linuxshellssh
Zuckerberg
Zuckerberg

Reputation: 205

How to execute a command over ssh and store the value in a variable

I am trying to get the value of uname -r from a remote machine over ssh and use that value in my local script flow.

kern_ver=uname -r
sshpass -p "$passwd" ssh -o StrictHostKeyChecking=no root@$c 'kern_ver=echo \$kern_ver'

But looks like the value is not getting passed back to the local script flow .

Upvotes: 1

Views: 4650

Answers (2)

Charles Duffy
Charles Duffy

Reputation: 295954

Capture is var=$(...), as always.

ssh is a bit interesting because it unconditionally invokes a remote shell, so working with completely arbitrary commands (as opposed to simple things like uname -r) requires a different technique:

filename="/path/to/name with spaces/and/ * wildcard characters *"
printf -v cmd_str '%q ' ls -l "$filename"
output=$(ssh "$host" "$cmd_str")

This way you can use arguments with spaces, and they'll be passed with correct quoting through to the remote system (with the caveat that non-printable characters may be quoted with bash-only syntax, so this is only guaranteed to work in cases where the remote shell is also bash).

Upvotes: 1

chepner
chepner

Reputation: 532418

Storing the command in the variable cmd is optional; you can hard-code the command as a string argument to ssh. The key is that you simply run the command on the remote host via ssh, and capture its output on the local host.

cmd="uname -r"
kern_ver=$(sshpass -p "$passwd" ssh -o StrictHostKeyChecking=no root@"$c" "$cmd")

Upvotes: 7

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