Question

A DevOps engineer writes a Bash script that must process a list of hostnames from a file called servers.txt. For each host, it should attempt an SSH connection test and print 'UP' only if the connection succeeds. The current loop always prints 'UP' regardless of connectivity:

while read host; do
  ssh -o ConnectTimeout=5 "$host" exit
  echo "$host UP"
done < servers.txt

Which modification correctly prints 'UP' only when the SSH command succeeds?

Accepted Answer

Wrap the ssh command in an if statement: if ssh -o ConnectTimeout=5 "$host" exit; then echo "$host UP"; fi

Answer

Change the echo line to: echo "$host UP" || ssh -o ConnectTimeout=5 "$host" exit

Answer

Add set -e at the top of the script so the loop stops when SSH fails

Answer

Test the variable with: if [ "$host" ]; then echo "$host UP"; fi