cant echo >> sudoers file 'permission denied: /etc/sudoers'

Question

I wanted to write a script to add some tools to my VPS or VMS and I write something like that

# Edit sudoers
echo -e "${GREEN}Configure sudoers...${NOCOLOR}"
echo
echo '# Allow user to use sudo without passwd' >> /etc/sudoers
echo '$USER ALL=(ALL) NOPASSWD:ALL' >> /etc/sudoers

this script run as Sudo and i test echo $USER in Sudo is the user name, not root I mean I'm kind of new so I did not know that and write this but when I test it I'm getting error permission error i don't know what to do I did some search but can't find anything

The answer to the title of the question is here on redirecting stdout to a file to which one does not have write permission. Therefore, I think the title might be edited a bit. — KevinO, Apr 01 '21 at 03:04
How exactly are you running this script? You said you run it as sudo, but are you running the script itself as root, or just the commands in it? Also, how are you running it in relation to the VPS/VMS/whatever? — Gordon Davisson, Apr 01 '21 at 04:13
Even if you run this with sudo, the redirection is done by the parent process, which is unprivileged. Also, single quoting (echo '$USER... prevents interpretation of $USER. To demonstrate: echo $USER; echo '$USER'; echo "$USER". — waltinator, Apr 01 '21 at 04:54
Does this answer your question? What is the safest way for programmatically writing to a file with root privileges? — Wieland, Apr 01 '21 at 06:25
@waltinator, if those commands are in a script, and the script is run with sudo scripts, the redirections inside will be done by the privileged shell which sudo ends up launching. — ilkkachu, Apr 01 '21 at 11:33
@notnexn and the confusion with sudo echo ... > ... is why you need to show what exactly it is you're trying to do. The full command line, and the associated error message. Just copy-paste them from the terminal, and [edit] your post to show. — ilkkachu, Apr 01 '21 at 11:34

score 1 · Answer 1 · edited Apr 01 '21 at 06:47

1

I have three things to point out there. One, you should really use visudo to edit the /etc/sudoers file, even if you set $EDITOR to a script that echoes that content. The other is that it is sub-optimal to let any user run any command without a password. Finally, $USER will equal root, so that will be pointless.

If you really want to do that, make a separate script that has this in it:

echo '# Allow user to use sudo without a password' >> $1
echo "$PERSON ALL=\(ALL\) NOPASSWD:ALL" >> $1

Second, make yet another script that runs your main script like this:

sudo "env PERSON=$USER /your/script/here"

That should tidy it up a bit, because you can be sure that the whole script is being run as root, and visudo keeps backups in case you screw up the sudoers file.

edited Apr 01 '21 at 06:47

Garo

2,059
11
16

answered Apr 01 '21 at 04:52

kettle

226

1

Or, rather than editing the sudoers file directly, create a separate file per user that just contains that line: echo "$USER ALL=(ALL) NOPASSWD:ALL" > /etc/sudoers.d/$USER. – berndbausch Apr 01 '21 at 05:32
That's also a good idea. The point of visudo is just not irreversibly screwing up the main file. – kettle Apr 01 '21 at 05:41

nltc · Accepted Answer · 2021-04-01T05:56:14.773

0

Instead of using:

sudo echo "# This is a comment" >> someFile.txt

You can use:

echo "# This is a comment" | sudo tee -a someFile.txt

NOTE: Don't forget the -a flag for the tee command, otherwise you will end up overwriting the whole file with the new comment line.

cant echo >> sudoers file 'permission denied: /etc/sudoers'

2 Answers2