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I am trying to run a script on remote server as a root user. I have this line in my shell script.

cat /home/myuser/create_user_updated.sh |   ssh myuser@$myip "sudo sh"

I get the following error.

sudo: sorry, you must have a tty to run sudo

The script "create_user_updated.sh" works ok if copy the file to remote server and execute it there locally. But it does not work from remote server.

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2 Answers

up vote 6 down vote accepted

You have two options:

  1. You can disable tty requirements by sudo: run visudo and either remove "requiretty" option globally if it is set, or on per-user basis:

    Defaults:username !requiretty

  2. You can force ssh to allocate pseudo-tty:

    ssh -t -t myuser@$myip "sudo sh"

    Note the double -t options, both are needed. Moreover, you need to add exit as a last line of your create_user_updated.sh script. Otherwise, ssh session might not end properly (because of the forced pseudo-tty creation).

Please use option #2 only if you don't have root rights on the target machine, and cannot change sudo config. #1 is much more clean solution. In my opinion, enforcing tty via sudo does very little from security standpoint.

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After running the script, I get some obscure prompt like sh3.22>> I have to hit ctrl+C to get the normal prompt. How do I avoid this since it must be because of -t -t option. – shantanuo Oct 13 '11 at 4:16
I updated my answer with the solution to this. Yes, this is because of -t -t option. – haimg Oct 13 '11 at 15:05
Don't forget that you can constrain the defaults declaration to not only a single username but to any spec, including command specs. This allows you to restrict the changes to only specific commands, groups of users or other spec. – Mark Carey Apr 25 at 19:48
up vote 0 down vote

Use visudo to edit the /etc/sudoers file and insert the below line:

Defaults:myuser !requiretty
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