in my bash loop over a list of some servers, if the ssh connects the bash script exits

Question

I have a quick script to run a command on each server using ssh (i am sure there are lots of better ways to do this, but it was intended to just work quick!!). For the test1

Answer 1

You should pass the -n flag to ssh, to prevent it messing with stdin:

ssh -n -q -oPasswordAuthentication=no -i id_dsa user1@${line} date

I tested this with my own server and reproduced the problem, adding -n solves it. As the ssh man page says:

Redirects stdin from /dev/null (actually, prevents reading from stdin)

In your example, ssh must have read from stdin, which messes up your read in the loop.

Answer 2

I think the reason is that as ssh is being forked and exec'd in your bash script the script's standard input is being reopened so your read simultaneously terminates. Try re-crafting as follows:

for line in test1 test2 server1 server2
do
    if [ "${line:0:1}" != "#"  ]; then
        ssh -q -oPasswordAuthentication=no -i id_dsa user1@${line} date
    fi
done

or maybe run the ssh in a sub-shell like this:

( ssh -q -oPasswordAuthentication=no -i id_dsa user1@${line} date )