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From: guido@boring.UUCP
Newsgroups: net.micro.mac
Subject: Re: How do you clear the "File Busy" bit?
Message-ID: <6760@boring.UUCP>
Date: Mon, 3-Feb-86 21:26:06 EST
Article-I.D.: boring.6760
Posted: Mon Feb  3 21:26:06 1986
Date-Received: Thu, 6-Feb-86 20:37:57 EST
References: <3157@sdcc3.UUCP> <602@sigma.UUCP>
Reply-To: guido@mcvax.UUCP (Guido van Rossum)
Organization: "Stamp Out BASIC" Committee, CWI, Amsterdam
Lines: 34
Apparently-To: rnews@mcvax

So far I've seen only descriptions of (sometimes failing) ways of
tricking various Finders into throwing away locked files in response
to this problem.

What *may* be the case here is something quite different from files
with the lock bit on: files that are still 'open'.  I don't know what
file transfer program you were using, but it may be the case that
when a transfer fails it doesn't properly close the file.  Unlike
real operating systems like UNIX (forgive the flame), the Mac doesn't
close open files when an application exits.  And open files can't be
deleted.  Since the file system's error code in this case is the same
as for files with the lock bit set (I believe), the error message
will almost undoubtedly be unclear about this possibility.  Even the
Finder can't cheat the file system here; it may clear the lock bit
when you press option while dragging to the trash, but it can't close
the file since it doesn't know the handle (knowledge about it vanished
when the application that opened it exited [see footnote]).

The only immediate cure is to reboot; to prevent the problem in the
future you should get your file transfer program fixed.  (If rebooting
doesn't make the file removable again, my guess at the problem's cause
above is wrong!)

__________
Footnote: in fact it would possible to close such a file: the PBGetFInfo
call returns the first handle to a file when it is open.  However, I
can see good reasons why the Finder should not try to mess with this,
even when the user overrides normal protections (such as open DA's
and running under the Switcher).  Also, the problem is really with the
application that failed to close the file (or with the design of the
operating system :-).

-- 
	Guido van Rossum, CWI, Amsterdam (guido@mcvax.UUCP)