Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!ucbvax!RODAN.ACS.SYR.EDU!jdpeek
From: jdpeek@RODAN.ACS.SYR.EDU (Jerry Peek)
Newsgroups: comp.unix.questions
Subject: Re: tail -f, does it lock the file while it scans ?
Message-ID: <8905210216.AA29056@rodan.acs.syr.edu>
Date: 21 May 89 03:16:52 GMT
References: <1268@usfvax2.EDU> <1623@auspex.auspex.com>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: Syracuse University; Syracuse, New York
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In article <1623@auspex.auspex.com> guy@auspex.auspex.com (Guy Harris) writes:
> >Does tail -f do some kind of file lock to prevent writing by another
> >proccess ??
> 
> No.

I didn't see the original article, so I apologize if someone already pointed
this out, but it seems like it's important...

I think most of the reason for *having* a "tail -f" is to be able to read a
file while another process is writing to it.  I use this all the time in cases
like:
	% some_slow_process > outputfile &
	[1] 12345
	% tail -f outputfile
	watch lines from outputfile
	as outputfile grows...
	whenever some_slow_process writes a line, I see it
I can kill the "tail -f", come back later, start it again... very nice.

--Jerry Peek; Syracuse University Academic Computing Services; Syracuse, NY
  jdpeek@rodan.acs.syr.edu, jdpeek@suvm.bitnet
  +1 315 443-3995