How to append to a file as sudo?

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 the following also doesn't work.

sudo echo "something" >> /etc/config_file

Is there a 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 -a 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"

Answer 3

Have sudo spawn a sub-shell:

sudo sh -c "echo 'JAVA_HOME=/usr/lib/jvm/java-6-sun' >> /etc/profile"

In this example, sudo runs "sh" with the rest as arguments.

(this is shown as an example in the sudo man page)

Answer 4

There may be a problem with the sudo here and the redirecting. Use a texteditor of your choice instead to add the line.

sudo nano /etc/profile

Or, you could try su instead

su
echo ‘JAVA_HOME=/usr/lib/jvm/java-6-sun’ >> /etc/profile
exit

Answer 5

In my opinion, the best in this case is dd:

sudo dd of=/etc/profile <<< END
JAVA_HOME=/usr/lib/jvm/java-6-sun
END

Answer 6

I usually use shell HERE document with sudo tee -a. Something along the lines of:

sudo tee -a /etc/profile.d/java.sh << 'EOF'
# configures JAVA
JAVA_HOME=/usr/lib/jvm/java-8-oracle
export JAVA_HOME
export PATH=$PATH:$JAVA_HOME/bin
EOF

Answer 7

This won't work you are trying to redirect (using >>) the output of sudo. What you really want to do is redirect the output of echo. I suggest you simply use your favorite editor and add that line manually to /etc/profile. This has the additional benefit that you can check whether /etc/profile already sets JAVA_HOME.

Answer 8

Use ex-way:

sudo ex +'$put =\"FOO\"' -cwq /etc/profile

and replace FOO with your variable to append.

In some systems (such as OS X), the /etc/profile file has 444 permissions, so if you still getting permission denied, check and correct the permission first:

sudo chmod 644 /etc/profile

then try again.