I know this does not help your actual error, but in the interest of security, there are a few things ...

• dont trust the user
• dont trust the user
• and, dont trust the user

I would suggest doing a few things. For each of the m//i's in the if/else, i suggest using lc(), and then using eq ... this prevents evil hacker code man motd from matching m/motd/i. Also, on the non-trusted user front, having the command coded in is very good, but i would think that the environment could have some very usefull information in it, were the wrong person to be pokiing around. This best thing to do, in the short term, is design a protocal for logging in (something as simple as FTP's login procedure).
Lastlky, on the error, i do not believe programs like motd use \r\n for newlines, so it is possible that is causing some issues.

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$ perl -e 'do() || ! do() ;'
Undefined subroutine &main::try
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