lsof in solaris

Hi ..

I have written a cronjob to invoke a script that would transfer files based on some criteria.
Consider folders A and B. Say I FTP a large file to A. Before the file gets fully transfered say the cronjob gets invoked. The script will move the file before its fully transfered. To detect such I used "lsof" in Redhat.
lsof |grep <filename> will give me the filename that is currently under transfer.But this is not working exactly the same way in Solaris..
Any ideas??
Thanks..

How exactly doesn't work ? Why not comparing the md5 sums of both files, and "sleep" a little bit more ?