Handle SystemExit exception

[asit]

My program contains some sys.exit(1) and when its executed an
exception known as SystemExit is thrown.

I tried to handle bu using following code snippet

if __name__ == "__main__":
    try:
        main()  #main contains sys.exit(1)
    except KeyboardInterrupt:
        print "aborted by user"
    except SystemExit:
        pass

But it does not work.

Can anyone help me out ???

Though KeyboradInterrupt is handled, but why SystemExit is not
handles ????

Regards
Asit Dhal