Somethings I still do in shell...

for user in `awk -F: '{print $1}' /etc/passwd`; do 
  echo $user; 
  su - $user -c "ls -l /path/to/dir/" >/dev/null 2>&1;  
  echo $?; 
done
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Yeah I wrote it on the command line :) You might need to tweak for your system, skipping system accounts for example (awk -F: '$3>100{print $1}' /etc/passwd usually does it).