linux - [Solved-5 Solutions] How to use sudo to redirect output to a location in Linux ? - ubuntu - red hat - debian - linux server - linux pc

To find myself quite often needing to redirect output to a location but don't normally have write access to.

The trouble is, the following example doesn't work:

sudo ls -hal /root/ > /root/test.out

You just receive the response:

-bash: /root/test.out: Permission denied

How can you get this to work?

Your command does not work because the redirection is performed by your shell which does not have the permission to write to /root/test.out. The redirection of the output is not performed by sudo.

There are multiple solutions:

sudo sh -c 'ls -hal /root/ > /root/test.out'

#!/bin/sh
ls -hal /root/ > /root/test.out

Run sudo ls.sh.

[nobody@so]$ sudo -s
[root@so]# ls -hal /root/ > /root/test.out
[root@so]# ^D
[nobody@so]$

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

The redirect to /dev/null is needed to stop tee from outputting to the screen. To append instead of overwriting the output file (>>), use tee -a or tee --append (the last one is specific to GNU coreutils).

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.

sudo ls -hal /root/ | sudo dd of=/root/test.out

sudo bash <<EOF
ls -hal /root/ > /root/test.out
EOF

Or of course:

echo 'ls -hal /root/ > /root/test.out' | sudo bash

Make sudo run a shell, like this:

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