Script to restart the network of multiple Centos hosts

Bl@ckJ@ck · 08-23-2012, 10:14 PM

Hi members,

I am new to Linux and I require some help here.

Basically I am tasked to get a way to restart the network of about 30 Centos servers.

The command I use is "service network restart"

Now is there a way to execute "service network restart" all the 30 servers WITHOUT having to manually login to all 30 servers?

I have got a primary server that already has passwordless connection to these 30 servers. All I need is a simple script to accomplish this.

Can anyone please guide me on this?

Thank you

Ser Olmy · 08-23-2012, 10:36 PM

ssh can take a "command" parameter: ssh user@hostname [command]

If you have passwordless ssh login, is should do the trick. It could then be scripted quite easily:

Code:

username=user
servers="server1 server2 server3"

for host in ${servers} ; do
  ssh ${user}@${host} service network restart
done

Note: I don't know how the "service" command works, and if you're reconfiguring all network connections, there's a chance the ssh session will terminate before the command finishes, leaving the network connections in an unknown state. If so, you may have to use "service network restart &" (including double quotes) to make the process fork into the background.

Bl@ckJ@ck · 08-23-2012, 10:54 PM

Thank you Ser Olmy

I will try this and update my results.
Appreciate your help

chrism01 · 08-23-2012, 11:23 PM

I think you'll need quote marks around the cmd sent

Ser Olmy · 08-23-2012, 11:29 PM

Quote:

Originally Posted by chrism01

I think you'll need quote marks around the cmd sent

Actually, no, although it certainly won't hurt. I tested this prior to posting:

Code:

ssh user@server ls -l

...and got a long listing. However, in order to send a character that would otherwise be interpreted by the shell, like &, quotes are obviously needed.

chrism01 · 08-23-2012, 11:32 PM

Yeah, I wasn't sure off the top of my head, but I'd definitely want to background the cmd in case it hangs or some such.
Basically, I think I always quote it just in case; defensive programming

Bl@ckJ@ck · 08-24-2012, 12:34 AM

Thanks Guys,

I still am having some problems.

Basically from my controlling server, I named and saved the scripts as network_restart.sh

Then from the controlling server, I ran the following command:
[root@Controller ~]# /root/scripts/network_restart.sh

Here is the result:
[root@Controller ~]# /root/scripts/network_restart.sh
-bash: /root/scripts/network_restart.sh: Permission denied

********************************************************************
This is the content of network_restart.sh
********************************************************************

#! /bin/bash
username=root
servers="10.1.88.88"

for host in ${servers} ; do
ssh ${user}@${host} "service network restart"
done
exit

I hope I am clear enough for you to help
Cheers

chrism01 · 08-24-2012, 12:44 AM

Code:

bash: /root/scripts/network_restart.sh: Permission denied

means what it says; either the file is not owned by caller or you haven't set executable perms on

Assuming this is a root only script (& it should be), you want it similar to this ; see chown http://linux.die.net/man/1/chown chmod http://linux.die.net/man/1/chmod

Code:

-rwx------. 1 root root   242 Aug 17 21:19 network_restart.sh

given you are new to Linux, I HIGHLY recommend you read
http://rute.2038bug.com/index.html.gz,
see also
http://tldp.org/LDP/Bash-Beginners-G...tml/index.html
http://www.tldp.org/LDP/abs/html/

and www.linuxtopia.org for LOTS of Manuals/books (free to read)

PS var name 'user' != var name 'username' in your script; pick one

PPS add

Code:

set -xv

as 2nd line of your script when debugging

Bl@ckJ@ck · 08-24-2012, 01:21 AM

Thanks Chris and Ser Olmy

I got it to work with your help