Shell command to delete old network users on Mac OS X Server

Question

I'm trying to delete old network user accounts off our lab server (Mac OS X 10.6). I found a simple command line command to find user directories that have not been accessed for over a year:

find /Volumes/Server-HD2/NetworkUsers/Students -type d -maxdepth 1 -mindepth 1 -not -name "." -mtime +356

Running this command successfully lists all of the old accounts. I then found what looks like a simple for loop, but it doesn't work:

#!/bin/bash

keep1="/Volumes/Server-HD2/NetworkUsers/Students/studenttest"
keep2="/Volumes/Server-HD2/NetworkUsers/Students/studenttest2"

USERLIST='find /Volumes/Server-HD2/NetworkUsers/Students -type d -maxdepth 1 -mindepth 1 -not -name "." -mtime +356'

for a in $USERLIST ; do
  [[ "$a" == "$keep1" ]] && continue                    #skip account 1
  [[ "$a" == "$keep2" ]] && continue                    #skip account 2
  echo "Deleting account and home directory for" $a
  dscl . delete $a                                      #delete the account
  rm -r $a                                              #delete the home directory
done

When I run this command as an executable shell file or just straight in the command line, it loops through $a as being each word in the $USERLIST. In other works if I simply do this:

USERLIST='find /Volumes/Server-HD2/NetworkUsers/Students -type d -maxdepth 1 -mindepth 1 -not -name "." -mtime +356'

for a in $USERLIST ; do 
   echo $a
done

It will return:

find
/Volumes/Server-HD2/NetworkUsers/Students
-type
d
-maxdepth
1
-mindepth
1
...

whereas I would expect it to return each directory that meets the "find" command.

I need to figure out how to make an array of the results from the find command to loop through. I guess I simply don't understand how the arrays and strings are handled in bash. Any thoughts?

Answer 1

You have enclosed your find command in the USERLIST assignment in single quotes – that will assign the whole command as a string to the $USERLIST variable (foregoing all shell expansion – that’s what single quotes are for). Instead, to get the command output assigned, you need to enclose it in backticks (`) or in a $(<command>) construct, i.e.

USERLIST=`find /Volumes/Server-HD2/NetworkUsers/Students -type d -maxdepth 1 -mindepth 1 -not -name "." -mtime +356`

or

USERLIST=$(find /Volumes/Server-HD2/NetworkUsers/Students -type d -maxdepth 1 -mindepth 1 -not -name "." -mtime +356)