How to use sudo with pipelines? [duplicate]

Possible Duplicate:
sudo & redirect output

Let's say I want to add some line into /etc/profile. I try:

$ sudo echo "something" >> /etc/profile
bash: /etc/profile: Access forbidden

Of course I could write:

$ sudo su
# echo "something" >> /etc/profile

and this works, however it does not work within a shell script.

So, what is the right way?

Solution 1:

You can use tee:

$ echo "something" | sudo tee -a /etc/profile

If you omit the -a (append) the file will be overwritten.

Solution 2:

Your version:

sudo echo "something" >> /etc/profile

In this command, echo is run as root, but the shell that's redirecting echo's output to the root-only file is still running as you. That's why you are getting "Access forbidden"

Working version:

sudo bash -c 'echo "something" >> /etc/profile'

In this command you use sudo to start a new shell with root privileges and then give that shell the whole command string (including the redirection) with the -c option of bash.