How to append to a file as sudo? [closed]

Question

Possible Duplicate:
sudo unable to write to /etc/profile

I want to do:

echo "something" >> /etc/config_file

But, since only the root user has write permission to this file, I can't do that. But this:

sudo echo "something" >> /etc/config_file

also doesn't work. Is there any way to append to a file in that situation without having to first open it with a sudo'd editor and then appending the new content by hand?

Answer 1

the right tool for the right task: 'tee'

tee - read from standard input and write to standard output and files

so your commandline becomes

% echo "output" | sudo tee --append file

the advantage of tee over executing bash with administrative permissions is:

• you do not execute bash with administrative permissions
• only the 'write to file' part runs with advanced permissions
• quoting of a complex command is much easier

Answer 2

The redirection is executed in the current shell. In order to do the redirection with elevated privileges, you must run the shell itself with elevated privileges:

sudo bash -c "somecommand >> somefile"