How to check if user has sudo privileges inside the bash script? - linux

Question

I would like to check if the user has sudo privileges. This is an approximate example of what I am trying to do. I am trying to get this to work across the following os: centos, ubuntu, arch.
if userIsSudo; then
chsh -s $(which zsh)
fi

Answer 1

Try with this:
$ sudo -v &> /dev/null && echo "Sudoer" || echo "Not sudoer"
Also, IDK how secure will be searching for his membership in the sudo group, i.e:
$ groups "$(id -un)" \
| grep -q ' sudo ' \
&& echo In sudo group \
|| echo Not in sudo group
Or:
$ getent group sudo \
| grep -qE "(:|,)$(id -un)(,|$)" \
&& echo in sudo group \
|| echo not in sudo group

Answer 2

sudo -l will display the commands that the user can run with sudo privileges. If there are no commands that can be run, sudo -l will return an error code and so you could try:
sudo -l && chsh -s $(which zsh)

Answer 3

Usually when you run an script you want to know if end it well or you got an error or what kind of error you got if there was any.
This is a more elaborated snippet, sudoer-script.sh:
## Define error code
E_NOTROOT=87 # Non-root exit error.
## check if is sudoer
if ! $(sudo -l &> /dev/null); then
echo 'Error: root privileges are needed to run this script'
exit $E_NOTROOT
fi
## do something else you
## means it was successfully executed
exit 0
Now you can reuse your script, pipe it or concatenate with other commands
sudoer-script.sh && ls
## in a script
if $(sudoer-script.sh); then
echo 'success'
fi
## capture error
stderr=$(./sudoer-script.sh 2>&1 >/dev/null)
echo $stderr
As a function:
is_sudoer() {
## Define error code
E_NOTROOT=87 # Non-root exit error.
## check if is sudoer
if ! $(sudo -l &> /dev/null); then
echo 'Error: root privileges are needed to run this script'
return $E_NOTROOT
fi
return 0
}
if is_sudoer; then
echo "Sudoer"
else
echo "Not sudoer"
fi