Editing the sudo file in a shell script

Question

I want to edit the sudoers files in Solaris by removing # or adding # in it on a specific line, so how can I write the script for this? My sudoer sample file given below:

# The following line allows su without options/arguments and sux to user root
Cmnd_Alias SU_ROOT = /usr/bin/su "",\
                     /usr/local/bin/sux - root

# Defaults specification
Defaults:%saptb !authenticate

# User privilege specification
%saptb  ALL=(root)SU_SAP
#Uncomment this line when SAP requires root access
%saptb ALL=(root)SU_ROOT
##### END SAP-TB specific  ######
#
#
#Tivoli ITM Tools Team Sudo Right
#
%cgtools        ALL=(root)       NOPASSWD: /opt/IBM/ITM/bin/*

---

In this above sudoers file i want add # before the only line of %saptb ALL=(root)SU_ROOT

Answer 1

Do a substitution with sed :

# Comment out the line %saptb ALL=(root)SU_ROOT
sudo sed -Ei 's/^(%saptb.*SU_ROOT.*)/#\1/' /etc/sudoers

Explanation:

-E use extended regex

-i edit the file in place.

s/         # Substitution
^          # Match the start of the line
(          # Capture the following
%saptb     # Followed by %saptb
.*         # Followed by anything
SU_ROOT    # Followed by SU_ROOT
.*         # Followed by anything
)          # Close capture
/          # Replace with 
#          # A hash 
\1         # Followed by the captured line

To uncomment lines the principle is the same:

1. Match the start of the line
2. Followed by a #
3. Capture the rest of the line
4. Replace whole line with captured part of the line (throwing away the # ).

So:

# Uncomment the line %saptb ALL=(root)SU_ROOT
sudo sed -Ei 's/^#(%saptb.*SU_ROOT.*)/\1/' /etc/sudoers

---

You can use the following script to comment/uncomment by running sudo ./toggle.sh

#!/bin/bash

# Is the line already commented out
grep -q '#%saptb ALL=(root)SU_ROOT' /etc/sudoers

if [ $? -eq 0 ]; then 
    # Uncomment the line %saptb ALL=(root)SU_ROOT
    sed -Ei 's/^#(%saptb.*SU_ROOT.*)/\1/' /etc/sudoers
else 
    # Comment out the line %saptb ALL=(root)SU_ROOT
    sed -Ei 's/^(%saptb.*SU_ROOT.*)/#\1/' /etc/sudoers
fi