l i n u x - u s e r s - g r o u p - o f - d a v i s
Next Meeting:
July 7: Social gathering
Next Installfest:
Latest News:
Jun. 14: June LUGOD meeting cancelled
Page last updated:
2002 Jun 24 16:30

The following is an archive of a post made to our 'vox-tech mailing list' by one of its subscribers.

Report this post as spam:

(Enter your email address)
Re: [vox-tech] Perl question: file handling
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [vox-tech] Perl question: file handling

Thanks Jeff, that helps.  But in this case the rename deletes
a file (with the same name) that's still open (and locked), 
and so the inode is going away, right?

I suppose the OS doesn't care since it was opened read-only, 
but it sure feels cheesy to me.

-- Rod

On Monday 24 June 2002 02:45 pm, Jeff Newmiller wrote:
> On Mon, 24 Jun 2002, Rod Roark wrote:
> > I'm looking at some Perl code (not mine) that does this
> > (simplified for clarity):
> >
> >   open(INFILE, "<$filename");
> >   flock INFILE, LOCK_EX;
> >   open(OUTFILE, ">$tempname");
> >   flock OUTFILE, LOCK_EX;
> >   ...
> >   (read from INFILE, change stuff, write to OUTFILE)
> >   ...
> >   rename $tempname, $filename;
> >   flock OUTFILE, LOCK_UN;
> >   close(OUTFILE);
> >   flock INFILE, LOCK_UN;
> >   close(INFILE);
> >
> > Notice that it's renaming/deleting files that are open and
> > locked.  Is this as insane as I think it is?
> No, it is not insane at all, if you are using a *nix-style filesystem.
> Think of rename as "mv"... it doesn't affect the file, rather it alters
> the directory entries that point at the file (inode).  No deletion is
> occurring, and any processes accessing the file are doing so through the
> inode, which is unaffected.
> This behaviour allows you to mv a logfile even while it is being written
> to, for example.  The process writing to the logfile cares not what you
> call it, and the next process to attempt to open the logfile finds no
> inode for that filename, and creates the new inode as needed.
> I hate the tied data/filename aspect of MSDOS/Windows that makes such
> tasks a b***h to implement.

vox-tech mailing list

LUGOD Group on LinkedIn
Sign up for LUGOD event announcements
Your email address:
LUGOD Group on Facebook
'Like' LUGOD on Facebook:

Hosting provided by:
Sunset Systems
Sunset Systems offers preconfigured Linux systems, remote system administration and custom software development.

LUGOD: Linux Users' Group of Davis
PO Box 2082, Davis, CA 95617
Contact Us

LUGOD is a 501(c)7 non-profit organization
based in Davis, California
and serving the Sacramento area.
"Linux" is a trademark of Linus Torvalds.

Sponsored in part by:
O'Reilly and Associates
For numerous book donations.