Code:
if (-e "/path/to/some.file") {
print "Found the file. Can't continue!";
exit 1;
}
Here are some other possibilities....
-r File is readable by effective uid/gid.
-w File is writable by effective uid/gid.
-x File is executable by effective uid/gid.
-o File is owned by effective uid.
-R File is readable by real uid/gid.
-W File is writable by real uid/gid.
-X File is executable by real uid/gid.
-O File is owned by real uid.
-e File exists.
-z File has zero size.
-s File has non-zero size (returns size).
-f File is a plain file.
-d File is a directory.
-l File is a symbolic link.
-p File is a named pipe (FIFO).
-S File is a socket.
-b File is a block special file.
-c File is a character special file.
-u File has setuid bit set.
-g File has setgid bit set.
-k File has sticky bit set.
-t Filehandle is opened to a tty.
-T File is a text file.
-B File is a binary file (opposite of -T).
-M Age of file in days when script started.
-A Same for access time.
-C Same for inode change time.
If you wish to use more than one option on the same file you should use an underscore after the first test, ie:
if (-e "/path/to/some.file" or -d _ or -z _) {