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From: scm@datlog.co.uk ( Steve Mawer )
Newsgroups: comp.unix.questions
Subject: Re: sorting and reversing lines of a file
Keywords: reverse file
Message-ID: <1774@dlvax2.datlog.co.uk>
Date: 21 Feb 89 11:02:46 GMT
References: <9056@burdvax.PRC.Unisys.COM> <9510@smoke.BRL.MIL> <899@auspex.UUCP> <2585@pegasus.ATT.COM>
Reply-To: scm@datlog.co.uk ( Steve Mawer )
Organization: Data Logic Ltd, Queens House, Greenhill Way, Harrow, London.
Lines: 25

In article <2585@pegasus.ATT.COM> hansen@pegasus.ATT.COM (Tony L. Hansen) writes:
>    WARNING
>	Command formats such as
>
>		tac file1 file2 >file1
>
>	will cause the original data in file1 to be lost, therefore, take
>	care when using shell special characters.
>
>    SEE ALSO
>	cat(1).

Note also that formats such as 

	   cat file1 file2 > file2

will cause your disk to become *very* full (as well as losing the original
contents of file2).

I can't speak for tac, since it won't do a simple first-to-last read of the
files.

-- 
Steve C. Mawer        <scm@datlog.co.uk> or < {backbone}!ukc!datlog!scm >
                       Voice:  +44 1 863 0383 (x2153)