Bash 脚本 - 如果 SSH 连接由于无效 IP 而失败，请不要运行程序并打印错误消息

Question

I'm trying to verify if an IP address is valid before starting the program. The user has to enter an IP address and password, and if the connection is unable to happen, there should be some connection timeout or error message. Is there a way to check if the ssh was successful before running a function in my program, and if not, the program should exit?

status=$(sshpass -p "$PASSWORD" ssh -o ConnectTimeout=5 root@"IP_ADDRESS" exit)

echo "Status: $status"

if [[ $status != 0]]; then
    echo "Connection failed. Re-check IP address or password."
else 
    startProgram
fi

I heard if the ssh was successful, it should return 0 - otherwise it would return a non-zero value. But, when I attempt to validate the connection this way, I always get the "Connect failed" message because status doesn't return any value. The echo statement just prints "Status: " regardless of whether my login credentials were correct or not.

Answer 1

status only contains the standard output from your command. You need to look at $? to get the return code.

status=$(sshpass -p "$PASSWORD" ssh -o ConnectTimeout=5 root@"IP_ADDRESS" exit)
retcode=$?
echo "Status: $status"

if [[ $retcode -ne 0 ]]; then
    echo "Connection failed. Re-check IP address or password."
else 
    startProgram
fi