How do I use sudo to redirect output to a location I don't have permission to write to?

Question

I\'ve been given sudo access on one of our development RedHat linux boxes, and I seem to find myself quite often needing to redirect output to a location I don\'t normally h

Answer 1

This is based on the answer involving tee. To make things easier I wrote a small script (I call it suwrite) and put it in /usr/local/bin/ with +x permission:

#! /bin/sh
if [ $# = 0 ] ; then
    echo "USAGE: <command writing to stdout> | suwrite [-a] <output file 1> ..." >&2
    exit 1
fi
for arg in "$@" ; do
    if [ ${arg#/dev/} != ${arg} ] ; then
        echo "Found dangerous argument ‘$arg’. Will exit."
        exit 2
    fi
done
sudo tee "$@" > /dev/null

As shown in the USAGE in the code, all you have to do is to pipe the output to this script followed by the desired superuser-accessible filename and it will automatically prompt you for your password if needed (since it includes sudo).

echo test | suwrite /root/test.txt

Note that since this is a simple wrapper for tee, it will also accept tee's -a option to append, and also supports writing to multiple files at the same time.

echo test2 | suwrite -a /root/test.txt
echo test-multi | suwrite /root/test-a.txt /root/test-b.txt

It also has some simplistic protection against writing to /dev/ devices which was a concern mentioned in one of the comments on this page.

Answer 2

Someone here has just suggested sudoing tee:

sudo ls -hal /root/ | sudo tee /root/test.out > /dev/null

This could also be used to redirect any command, to a directory that you do not have access to. It works because the tee program is effectively an "echo to a file" program, and the redirect to /dev/null is to stop it also outputting to the screen to keep it the same as the original contrived example above.

Answer 3

Make sudo run a shell, like this:

sudo sh -c "echo foo > ~root/out"