Shell script calls sudo; how do I suppress the password prompt

Question

I am writing a simple shell script which changes the mac address of the network hardware. One of the line is :

sudo ifconfig eth0 hw ether 00:99:99:00:00:00

My problem is with sudo the script prompts for password. Is there any way that I could do this without prompting the user for password ???

Answer 1

Most definitely, if you don't mind making that particular command 'free for use' for that particular user:

See basically my other answer here: Shell script - Sudo-permissions lost over time

The simplest thing that may work is

myuser = NOPASSWD: /sbin/ifconfig

Also, you could sudo an arbitrary command on the same terminal (tty/vty), and sudo will cache the authentication for a while (or until sudo -k), so you may start the script and it will 'remember' the credentials from your earlier sudo invocation. I sometimes do this when composing pipes with sudo (just preceded them with sudo true)

Answer 2

echo "password" | sudo -S ifconfig eth0 hw ether 00:99:99:00:00:00

Answer 3

You need a sudo configuration line which allows for the command to be executed by the user without password prompt.

You can disable the password prompt for a whole user (more dangerous, but perhaps ok if you are the only user on your desktop -- DONT do this on a server ):

yourusername  ALL=(ALL) NOPASSWD: ALL

or more restrictive, only allowing the ifconfig command:

yourusername  ALL= NOPASSWD: /sbin/ifconfig

See: man sudoers , man sudo

http://ubuntuforums.org/showthread.php?t=1132821

http://www.linuxhelp.net/guides/sudo/