The problem with Juerd's is that it offers no error checking. This one does:

perl -ple'$_=eval||$@||0'
[download]

For example:

$ perl -ple'$_=eval'
1/0
[download]

$ perl -ple'$_=eval||$@||0'
1/0
Illegal division by zero at (eval 1) line 2, <> line 1.
[download]

-sauoq
"My two cents aren't worth a dime.";