Unix：ssh 正在通过命令行而不是通过脚本工作

Question

Below command is working through command line:

expect -c 'spawn ssh username@Host ; expect "assword:" ; send "<password>\r" ; interact;'

Below is not working if I include in a script

while read server_from_file
do
    expect -c 'spawn ssh username@${server_from_file}; expect "assword:" ; send "<password>\r" ; interact;'
done < serverlist.conf

Please also let me know how could we run certain commands using the above script

Answer 1

expect inherits stdin from its environment. In the first case, expect uses the script's stdin as its stdin. In the second case, expect inherits stdin from the enclosing while loop, so it will be reading from the file. One typical solution would be to use a different fd for the loop. eg:

while read server_from_file <&3  
do
    expect -c 'spawn ssh username@${server_from_file}; expect "assword:" ; send "<password>\r" ; interact;'
done <3 serverlist.conf

(Note, some shells provide -u, and there are other ways to do this, but this should get you pointed in the right direction.)