Automatic input "yes" in a shell script

Shell Programming and Scripting
1

Hi All,

I need a favour.

I have a file called "redhat_servers.txt" containing some server names line by line.

When I try to ssh to each server, and I have already done with ssh key-gen stuff. Now, for first time if I do ssh .. I need to type yes I have more than 400 servers...it will take long time to ssh to each server and type yes

I need to write a script for this.

redhat_servers.txt file looks like this

sxs1
sxs2
sxs3
-
-
-
sxs109

Please help me, how can I do this in script.

Thanks
Siva

2

You leave us guessing why you have to enter "yes". Is it in response to the question

The authenticity of host 'nnn.nnn.nnn.nnn' can't be established.
RSA key fingerprint is xx:xx:xx:xx:....
Are you sure you want to continue connecting (yes/no)?

Then you need those servers' entries in .ssh/known_hosts , and the question is gone...

3

Hello Siva,

You can use expect script for same. Following may help.

cat test.ksh
while read line
do
 ./ssh_test.ksh test_user@"$line"
done < "server_list"

Where ssh_test.ksh is the expect script.

cat ssh_test.ksh
#!/usr/bin/expect  #Usage sshsudologin.expect <host> <ssh user> <ssh password> 
set timeout 60   
spawn ssh [lindex $argv 1]@[lindex $argv 0]   
expect "yes/no" {      
send "yes\r"    
}   
interact

So in input file server_list you can provide all servers names and while running ssh_test.ksh script it will one by one do a ssh to all the servers present in list file and will send yes to all the servers during ssh . You can change it as per your need too.

NOTE: As per your post you have done key gen already so it is only to enter yes during ssh .

Thanks,
R. Singh

4

One could use:
' a programs own's -y toggle' only where applicable, eg: yum update -y
Does not apply to ssh, but might for other commands - see their -h or --help output.

But also, as root: (using fdisk, since you didnt show what you tried so far)

fdisk /dev/sda << EOF
?
i
1
q
EOF

(question of my own: is this a here-doc thing?)

Hope this helps

5

You cannot answer security questions with a here-document, it demands a terminal.

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