anchor.diff:  
   RUN_AS::
     User to run the script.
  -  If you execute the script as a different user than the one specified by `$RUN_AS`, then it will switch to the specified user using `su`.
  +  If you execute the script as a different user than the one specified by `$RUN_AS`, it will switch to the specified user using `su`.
     Default is empty, i.e. do not switch user.
   
   SYSLOG::
  
positive.code: Then you must define functions `pre-backup`, `post-backup` and optionally `setup`.
  
  setup()::
    If defined, then this function is executed before each `pre-backup()` and `post-backup()`, in the same environment.
    You may use it to check if required variables are set (using `required-var()`), to define some common variables or anything else that should be run before `pre-backup()` and `post-backup()`.
  
  pre-backup()::
    This function is executed when you run the script as a file named `pre-backup` (e.g. using symlink) or with argument `-c pre-backup`.
  
negative.code: * `/etc/bacula/prebackup.conf` – global configuration file (you can modify this path in link:bin/prebackup[]),
  * `./config` – local configuration file located in the same directory as the pair of `pre-backup` and `post-backup` symlinks (or file and symlink) used to run the script for a particular job.
  
  These files are just another shell scripts, but you _should_ define only variables here.
  The files are sourced in the defined order before an actual prebackup script.
  If both files exist and define the same variable, the local config overrides the global.
  
  
  == Predefined Variables
  