SSH not releasing terminal

Question

Hello,

When I run the following command from my macbook to my ubuntu server the terminal does not get released. It just sits there until I Control-C the command.

ssh user@my-server 'sudo /etc/init.d/nginx start'

When i login and then run the command everything works fine.

ssh user@my-server
sudo /etc/init.d/nginx start

Here is the output highlighting the issue

~ $ ssh [email protected]
[email protected]'s password:
Last login: Mon Sep  6 15:18:18 2010 from
me@somewhere:~$ sudo /etc/init.d/nginx restart
[sudo] password for me:
Restarting nginx daemon: nginx.
me@somewhere:~$ exit
logout
Connection to somewhere.com closed.
~ $ ssh [email protected] 'sudo /etc/init.d/nginx restart'
[email protected]'s password:
[sudo] password for me:

Restarting nginx daemon: nginx.

After the last command executes it just holds there and does nothing. Thanks in advance for any advice you might have.

me@somewhere:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=8.04
DISTRIB_CODENAME=hardy
DISTRIB_DESCRIPTION="Ubuntu 8.04.4 LTS"
me@somewhere:~$

Update:

I thought the init script might have a bug in it too. I have since used 3 different versions of an init script for niginx and all 3 have had the same issue. I am currently running this script which seems to be the pick of the 3 I found.

http://wiki.nginx.org/Nginx-init-ubuntu

I just tried the command suggested in the comments, and the issue is exactly the same. Any other ideas?

Answer 1

OK I managed to fix this by forcing pseudo-tty allocation. Simply add the -t option to the SSH command. This fixes the issue and still allows you to see the output. So...

ssh user@my-server 'sudo /etc/init.d/nginx start'

becomes...

ssh -t user@my-server 'sudo /etc/init.d/nginx start'

Answer 2

Short version:

let try this in 2 steps:

1. Create a script with your command on your server
2. Launch that script from your laptop

Detailed version

On your ubuntu box, create a script (let's say /my/path/nginx-my-start.sh) with this content

sudo /etc/init.d/nginx start 1>/dev/null

Don't forget to give it execution rights (chmod +x /my/path/nginx-my-start.sh)

Then from your laptop, call:

ssh user@my-server /my/path/nginx-my-start.sh

Explanations

I had exactly the same problem with a tomcat I wanted to remotely start. Adding the stdout redirection '1>/dev/null' in the script did the job.