sending an output to another comand

Question

I'm making a script that reads passwords from pass to ssh, I want to stop the script if the hostname is not found but I don't know how to read the output of ssh

I've tried this

test=$(ssh user@nonvalidip)
check="ssh: Could not resolve hostname nonvalidip: Name or service not known"
if [ $test = $check ]; then
echo "Please enter a valid ip"
fi

but $test is empty, how can I read the output of ssh and make that the test variable?

`if getent hosts nonvalidip >/dev/null; then echo ok; else echo unknown; fi`? — Cyrus, Aug 24 '19 at 21:26

score 0 · Answer 1 · answered Aug 24 '19 at 22:15

Assuming that you are trying to run a shell script to gain access through a system through SSH then if that connection is successful to run a command. To do this there are multiple things you could do that are much simpler than trying to make an interpret less language work. What I would strongly suggest is that to solve the first issue is to make a smaller script within the script. Such as doing something like this:

ssh user@known_address << EOF - This will start the session and keep everything running beneath it until it reaches the term EOF

Using this may help you later if you are in the Linux industry as well. The script should look something like this:

ssh user@known_address << EOF scp /etc/passwd USER@your_address/Path EOF - keep note that this is an example of what you can do but it is not very wise to keep extra copies of the password file laying around on other systems.

Then instead of using exact copies of what the system outputs you can simply use exit codes. This can be WAY more helpful along the way. You can receive the error codes of the last command you ran with echo $?

I cannot guarantee that this script will work but here's an example of what you can do

session() {ssh user@add << EOF; command1; command2; command3; EOF}; session; if $? == 1; echo "test failed".