How to write a shell script that runs some commands as superuser and some commands not as superuser without having to babysit it

Question

I want to write a shell script to automate a series of commands  The problem is some commands MUST be run as superuser and some commands MUST NOT be run as superuser  What I have done so far is something like this      bin bash  command1 sudo command2 command3 sudo command4   The problem is  this means somebody has to wait until command1 finishes before they are prompted for a password  then  if command3 takes long enough  they will then have to wait for command3 to finish  It would be nice if the person could get up and walk away  then come back an hour later and be done  For example  the following script has this problem      bin bash  sleep 310 sudo echo  Hi  I m root  sleep 310 sudo echo  I m still root     How can I make it so that the user can just enter their password once  at the very start  and then walk away   Update   Thanks for the responses  I m running on Mac OS X Lion and ran Stephen P s script and got different results   I also added  HOME   pair abbey scratch    test2 sh uid is 501 user is pair username is  home directory is  Users pair pair abbey scratch  sudo   test2 sh  Password  uid is 0 user is root username is root home directory is  Users pair

User · Answer

You should run your entire script as superuser. If you want to run some command as non-superuser, use "-u" option of sudo:

#!/bin/bash

sudo -u username command1
command2
sudo -u username command3
command4

When running as root, sudo doesn't ask for a password.

User · Answer

File sutest     bin bash echo  uid is   UID   echo  user is   USER   echo  username is   USERNAME     run it     sutest  gives me  uid is 500 user is stephenp username is stephenp   but using sudo  sudo   sutest gives  uid is 0 user is root username is stephenp   So you retain the original user name in  USERNAME when running as sudo  This leads to a solution similar to what others posted      bin bash sudo -u   USERNAME  normal command 1 root command 1 root command 2 sudo -u   USERNAME  normal command 2   etc    Just sudo to invoke your script in the first place  it will prompt for the password once     I originally wrote this answer on Linux  which does have some differences with OS X  OS X  I m testing this on Mountain Lion 10 8 3  has an environment variable SUDO USER when you re running sudo  which can be used in place of USERNAME above  or to be more cross-platform the script could check to see if SUDO USER is set and use it if so  or use USERNAME if that s set   Changing the original script for OS X  it becomes        bin bash sudo -u   SUDO USER  normal command 1 root command 1 root command 2 sudo -u   SUDO USER  normal command 2   etc    A first stab at making it cross-platform could be        bin bash     set  THE USER  to SUDO USER if that s set     else set it to USERNAME if THAT is set      else set it to the string  unknown    should probably then test to see if it s  unknown    THE USER   SUDO USER -  USERNAME -unknown    sudo -u   THE USER  normal command 1 root command 1 root command 2 sudo -u   THE USER  normal command 2   etc

User · Answer

If you use this  check man sudo too      bin bash  sudo echo  Hi  I m root   sudo -u nobody echo  I m nobody   sudo -u 1000 touch  test user

User · Answer

Well  you have some options     You could configure sudo to not prompt for a password   This is not recommended  due to the security risks   You could write an expect script to read the password and supply it to sudo when required  but that s clunky and fragile   I would recommend designing the script to run as root and drop its privileges whenever they re not needed   Simply have it sudo -u someotheruser command for the commands that don t require root    If they have to run specifically as the user invoking the script  then you could have the script save the uid and invoke a second script via sudo with the id as an argument  so it knows who to su to

[unix] How to write a shell script that runs some commands as superuser and some commands not as superuser, without having to babysit it?

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