~/tmp$ ./x
bash: ./x: /blabla: bad interpreter: No such file or directory
~/tmp$ perl -e 'exec("x") || die($!)'
No such file or directory at -e line 1.
~/tmp$ perl -e 'exec("~/tmp/x") || die($!)'
sh: /home/svenXY/tmp/x: /blabla: bad interpreter: No such file or dire
+ctory
[download]

$ perl -e 'exec("pwd") || die($!)'
/home/svenXY/tmp
[download]

exec respects $ENV{PATH} (or rather, exec uses the OS, and the OS respects $ENV{PATH}), and "." seems to be not in the path (and the OS seems to be one which does not have "." as a mandatory default in the list of directories searched for the executable).

In both cases -- according to ktrace(1) on FreeBSD 6-STABLE with Perl 5.8.8 in zsh 4 -- perl is complaining, through execve(2), about the missing interpreter not the file itself being executed.

Corion's reply reminded me that I just had added '.' to the path; thanks. It turns out the message, or rather error from execve(2), is the same whether the problem is not finding the file being executed, or if found, with missing interpreter listed in the file. Anyawy, what OP said.