How do I maintain sudo in a bash script?

Question

If I run this script, how do I pass super user permissions to it? I wrote this just to setup new machines with the basics. I don't want to run every command with elevated permissions, but the commands that do have sudo I want to run with them.

How do I have some commands run with sudo and others run as the regular user?

#!/bin/sh
# If Linux, install nodeJS
if $(uname) = 'Linux';
then
 export IS_LINUX=1
 # Does it have aptitude?
 if -x "which apt-get";
 then
 export HAS_APT=1
 # Install NodeJS
 sudo apt-get install --yes nodejs
 fi
 # Does it have yum?
 if -x "which yum" ;
 then
 export HAS_YUM=1
 # Install NodeJS
 sudo yum install nodejs npm
 fi
 # Does it have pacman?
 if -x "which pacman" ;
 then
 export HAS_PACMAN=1
 # Install NodeJS
 pacman -S nodejs npm
 fi
fi
# If OSx, install Homebrew and NodeJS
if $(uname) = 'Darwin' ;
then
 export IS_MAC=1
 if test ! "$(which brew)"
 then
 echo "================================"
 echo " Installing Homebrew for you."
 echo "================================"
 ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
 export HAS_BREW=1
 elif -x 'which brew' ;
 then
 export HAS_BREW=1
 brew update
 fi
 # Install NodeJS
 brew install --quiet node
fi
# Does it have python?
if -x "which python" ;
then
 export HAS_PYTHON=1
 if -x "which pip" ;
 then
 pip list --outdated | cut -d ' ' -f1 | xargs -n1 pip install -U
 export HAS_PIP=1
 fi
fi
# Does it have node package manager?
if -x "which npm" ;
then
 export HAS_NPM=1
else
 echo "NPM install failed, please do manually"
fi
# Does it have ruby gems?
if -x "which gem" ;
then
 export HAS_GEM=1
fi

The rest of the bash script (that I didn't include for length) installs packages from an array using npm, apt, yum, brew, or pacman, depending on the machine. It only installs simple things like git, wget, etc.

• G-Man Says 'Reinstate Monica': Related: sudo in non-interactive script.

Answer 1

First time sudo is invoked password is prompted for. Then, depending on configuration, if invoked within N minutes (default 5 minutes IIRC), one do not need to enter password again.

You could do something like:

sudo echo >/dev/null || exit 1

or perhaps something like:

sudo -p "Become Super: " printf "" || exit 1

at start of script.

If you want to prevent anyone from doing sudo ./your_script you should check EUID as well (bash):

if [[ $EUID -eq 0 ]]
then
 printf "Please run as normal user.\n" >&2
 exit 1
fi

or something like:

if [ "$(id -u)" = "0" ]
 ...

In any case also check out which shell you targetr. I.e.

• https://wiki.debian.org/DashAsBinSh
• https://wiki.ubuntu.com/DashAsBinSh
• https://lwn.net/Articles/343924/

etc.

---

To "keep it alive" one could do something like:

while true; do
 sleep 300
 sudo -n true
 kill -0 "$$" 2>/dev/null || exit
done &

• AtHeartEngineer: Great idea! How do I then allow only some parts of the bash script to run as sudo and others to run as a normal user? While maintaining the ability to use sudo without it timing out?
• Runium: @Tyler.Exposure: Expanded a bit. You allow any command to be run as sudo by prepending it by sudo ... I might not get what you are asking.
• AtHeartEngineer: Awesome, ok I think sleep -n works!!! Thank you!!!