Hello,

I have a backup script that runs an rsync backup to an external drive. I use the script frequently on Windows and Linux and have installed it on a Mac. The script has an option to run shutdown after the backup has completed. Since backup can take hours to run, this is an option that is set when the script starts and is executed when the script is finished (usually long after I have gone to bed).

The script looks more or less like this,

Code:

#!/bin/bash

# read input to shutdown after script or not
echo " "
echo "do you want to shutdown after the backup is finished? (y/n)  "
read shutdown_response

...
backup stuff
...

# shutdown if asked to   
if [ "$shutdown_response" = "y" ]; then
   echo " "
   echo "shutting down"
   shutdown -s now
fi

# prompt to exit script if not shutting down
echo " "
echo "press enter to exit script"
read exit_response
sleep 1
exit

This works well on Linux and Windows cygwin. In MacOS, the backup works correctly, but I get an error from the shutdown command that I am not super user. This does not happen under Windows or Linux, I guess because I am running from an account with administrator. My user account on MacOS is administrator, but sudo appears frequently and apparently shutdown is one of the tasks that requires password authentication.

I can add a command to switch to super user, sudo su , so that when the user specifies that they want to shutdown they can enter their password (you have to use sudo to switch to su in MacOS, more or less).

That version looks like,

Code:

#!/bin/bash

# read input to shutdown after script or not
echo " "
echo "do you want to shutdown after the backup is finished? (y/n)  "
read shutdown_response

# shutdown if asked to   
if [ "$shutdown_response" = "y" ]; then
   echo "enter your password for shutdown"
   sudo su
fi

...
backup stuff
...

# shutdown if asked to   
if [ "$shutdown_response" = "y" ]; then
   echo " "
   echo "shutting down"
   shutdown -s now
fi
# prompt to exit script if not shutting down
echo " "
echo "press enter to exit script"
read exit_response
sleep 1
exit

It looks like sudo su opens a new subshell and so the script does not continue to run. I really can't see an easy way around this. Maybe I could have a calling script that would run two different versions of the backup script, one called with sudo and the other not, but I'm not sure about that.

Is there a standard way to handle this?

LMHmedchem