I recently downloaded and installed Tiger (Tiger - The UNIX Security audit and intrusion detection tool)

The more desirable is to use 'tigercron'. With 'tigercron', it is
possible to run the individual scripts spread out over a time period
(some can be run three times a day, others once a week or month).
In addition, 'tigercron' will (on some systems) e-mail a "change"
report to the specified person (in 'tigerrc'). The "change" report
will only contain "new" information and will only be mailed when
there *is* new information.
But when I run tigercron I end up with this output:

Code:
user@machine:~$ sudo tigercron 
Password:
Configuring...
 
Will try to check using config for 'arch' running 'kernel'...
--CONFIG-- [con005c] Using configuration files for 'kernel'. Using
           configuration files for generic Linux 2.
           Not all checks may be performed.
--ERROR-- [init001e] Don't have required command MAILER.
I'm not sure what command it is looking for, there is an entry in tigerrc "Tiger_Mail_RCPT='root'" but I haven't managed getting it working. Inputting init001e into tigexp gives this response:

The indicated variable, which should specifies the pathname to a command,
does not have a value. This message should not appear on platforms
for which support is listed. If it does appear, then for the missing
commands, if you know the name of the command, then simply place it into
the environment and rerun the checking system.

setenv AWK /usr/bin/awk

./tiger

Or alternately, create a 'site' configuration file and insert an
assignment statement in there of the form:

AWK=/usr/bin/awk
Any help would be appreciated.