sudo nohup and redirection

Question

Trying to figure out the correct Cmnd_Alias for the sudoers file

The command i which to run without any password is the following:

sudo /usr/bin/nohup /etc/init.d/axtty start >/dev/null 2>&1

The lines i have added to sudoers file is:

## Cmnd alias specification
Cmnd_Alias AXTOOLTTYSTART = /usr/bin/nohup /etc/init.d/axtty start >/dev/null 2>&1
Cmnd_Alias AXTOOLTTYSTOP = /etc/init.d/axtty stop
Cmnd_Alias AXTOOLTTYSTATUS = /etc/init.d/axtty status
Cmnd_Alias AXTOOLINTCTLSTART = /sbin/initctl start ttyp?
Cmnd_Alias AXTOOLINTCTLSTOP = /sbin/initctl stop ttyp?

## This will disable password request for the axtools commands
%sudoaxtools ALL=(root) NOPASSWD: AXTOOLTTYSTART, AXTOOLTTYSTOP, AXTOOLTTYSTATUS, AXTOOLINTCTLSTART, AXTOOLINTCTLSTOP
Defaults!AXTOOLTTYSTART !requiretty
Defaults!AXTOOLTTYSTOP !requiretty

The command in mention is ran inside a script (axopen), executed either by member of group sudoaxtools or root's crontab

/usr/local/bin/axopen

#!/bin/sh

SUDO=''
if (( $EUID != 0 )); then
    SUDO='sudo'
fi

echo -n "Checking for open connections"
while netstat -d | grep -q axel
do
  ((c++)) && ((c==900)) && break
  echo -n "."
  sleep 4
done
echo "done"

echo "Starting axtty service.."
$SUDO /usr/bin/nohup /etc/init.d/axtty start >/dev/null 2>&1
sleep 4
$SUDO /etc/init.d/axtty status

When axopen is executed på member of sudoaxtools, then it still prompts for password. I expect its because of the >/dev/null 2>&1 pieces.

Secondary

The reason i'm using nohup is because the service for some reason will not start, when executed simply using

sudo /etc/init.d/axtty start

So if someone have ideas to fix that, it will be great as well.

Answer 1

You don't want the redirections as part of the sudo rule. /etc/sudoers contains the program that is executed, and the redirections happen separately (at the containing shell level) from the sudo command:

(shell) sudo /usr/bin/nohup /etc/init.d/axtty start >/dev/null 2>&1

This calls sudo and redirects the output; sudo sees:

(sudo) /usr/bin/nohup /etc/init.d/axtty start

Change this sudoers line:

Cmnd_Alias AXTOOLTTYSTART = /usr/bin/nohup /etc/init.d/axtty start >/dev/null 2>&1

to:

Cmnd_Alias AXTOOLTTYSTART = /usr/bin/nohup /etc/init.d/axtty start

Answer 2

I ended up putting the nohup script in a seperate bash script.

/usr/local/bin/axttystart

#!/bin/sh

## Intermediate bashscript in order to sudo nohup properly
/usr/bin/nohup /etc/init.d/axtty start >/dev/null 2>&1

Then changed sudo'ers line containing the Cmnd_alias for AXTOOLTTYSTART to

Cmnd_Alias AXTOOLTTYSTART = /usr/local/bin/axttystart

The updated axopen script will instead for the sudoing the nohup line directly, sudo the axttystart script

#!/bin/sh

[...]

echo "Starting axtty service.."
$SUDO /usr/local/bin/axttystart
sleep 4
$SUDO /etc/init.d/axtty status