How can I append text to /etc/apt/sources.list from the command line?

Question

I am new to linux, and just beginning to learn bash. I am using Ubuntu 9.04, and would like to add repositories to /etc/apt/sources.list from the command line. Basically, I would like to do this:

sudo echo "[some repository]" >> /etc/apt/sources.list 

However, even when I use sudo, I get this error:

bash: /etc/apt/sources.list: Permission denied 

How do I avoid this error?

Answer 1

echo "[some repository]" | sudo tee -a /etc/apt/sources.list 

The tee command is called as the superuser via sudo and the -a argument tells tee to append to the file instead of overwriting it.

Your original command failed, as the IO redirection with >> will be done as the regular user, only your echo was executed with sudo.

Calling a sudo subshell like

sudo sh -c 'echo "[some repository]" >> /etc/apt/sources.list' 

works, too as pointed out by others.