我如何在linux的exec命令中执行多个命令

Question

I'm trying to detect a host is available by using expect of Linux.

Now, I can using the following commands via bash to get the return value and check host status.

#!/usr/bin/bash
nc -z $DUT_IP 22 && echo $?

I want to do the same things via expect. But seems I failed.

#!/usr/bin/expect --   
set DUT_IP "192.168.1.9"
set result [exec nc -z $DUT_IP 22] 
send_user "$result\n\n"

I got the following error messages:

    invalid port &&
        while executing
    "exec nc -z $DUT_IP 22 && echo $?"
        invoked from within
    "set result [exec nc -z $DUT_IP 22 && echo $?] "
        (file "reboot.exp" line 44)

Answer 1

Use of && to separate commands is a shell construct, not an expect construct. You can explicitly launch a shell for that command list:

set result [exec sh -c "nc -z $DUT_IP 22 && echo $?"]

Note that will only print the exit status if the command succeeded , thus result will either be "0" or empty. You want to use ; instead of &&