Path: utzoo!utgpu!watserv1!watmath!att!mcdchg!ddsw1!corpane!disk!stevenw
From: stevenw@disk.UUCP (Steven Weller)
Newsgroups: comp.os.os9
Subject: Re: pd software/unix utils
Keywords: os9 unix utilities
Message-ID: <3919@disk.UUCP>
Date: 14 Aug 90 13:06:01 GMT
References: <1990Aug7.185337.4532@cs.utk.edu> <2394@mcrware.UUCP> <3300@rwthinf.UUCP>
Organization: Digital Information Systems of Ky (DISK), Louisville, Ky
Lines: 26


Re: Unix mv utility:

It is not necessary to use system calls if all you want to do is 
copy-then-delete.  Simply write a program mv that collects all its
command-line parameters asnd forks copy with them.  If that is 
successful (ONLY if it is successful !) fork del to delete the 
file(s) with appropriate arguments.

The Unix mv does some clever things: it moves the references to the
data, not the data itself.  This is where the problems occur
on OS-9.  Several processes can try to do this at once, resulting
in a damaged file structure.

The solution (I have not tried this) is to use record locking.
If you consult the technical manual, you find that the record
locking facilities of RBF are quite comprehensive.  The mv utility
must lock out all the files (i.e. directories and files)
conerned with the operation, do the critical work, then close 
all the files.

-- 
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