Date: Wed, 27 Sep 2017 22:28:11 +0200 From: Matthias Apitz <guru@unixarea.de> To: list@museum.rain.com Cc: freebsd-questions@freebsd.org Subject: Re: Possible bug in tail(1) Message-ID: <20170927202811.GA2799@c720-r314251> In-Reply-To: <20170927195828.GA77592@g5.umpquanet.com> References: <20170927195828.GA77592@g5.umpquanet.com>
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--HlL+5n6rz5pIUxbD Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable El d=C3=ADa mi=C3=A9rcoles, septiembre 27, 2017 a las 12:58:28p. m. -0700, = list@museum.rain.com escribi=C3=B3: > Is it reasonable to expect that tail -r is reversable? That is, should: >=20 > tail -r foo | tail -r >=20 > produce the same output as: >=20 > cat foo >=20 > for all text files foo? >=20 > The script below creates a file foo for which the above does not > hold. The essence of the issue seems to be if tail(1) is reading a file/stdin or a pipe: $ cat foor 3 2 1 $ tail -r foor 1 2 3 $ tail -r < foor 1 2 3 $ cat foor | tail -r 1 2 3 --=20 Matthias Apitz, =E2=9C=89 guru@unixarea.de, =E2=8C=82 http://www.unixarea.d= e/ =E2=98=8E +49-176-38902045 Public GnuPG key: http://www.unixarea.de/key.pub 8. Mai 1945: Wer nicht feiert hat den Krieg verloren. 8 de mayo de 1945: Quien no festeja perdi=C3=B3 la Guerra. May 8, 1945: Who does not celebrate lost the War. --HlL+5n6rz5pIUxbD Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEXmn7rBYYViyzy/vBR8z35Hb+nREFAlnMCdgACgkQR8z35Hb+ nRFiVQ//UbnswQfhIonTZIsXYGeO6uzbMNKseJ3VKThE3dm20QZqYCQFUQSrqCM7 92qi0JQESeXvezOltvlpg7kX4on980lqKd/BT9BzaRyxAs8DPkD/n/fVKUBFgMNH ULzHSfmr+faSyEljrJ9AZFhsgaQgPb7y7upnYd/C9Wt/twy1EfaJTriZIStSrmnv q1wxX8ciR6+feBDGDhq6LQ83XZkEVhBES8STCtgSvDzArJra+20d1oOGtg1ChRfS WVi/aEVMUBelPkrYdpLRAgqVViOJ9P+gM+rwzHn6LDpBf9WIRWsmYAtUjVYnkONa 2K3IX0BNL3dysQyJ2cReTVDq2jra3J/dsyF+mCIIyvhStgkU7jPtAgos1iGAH7tb /tEujk1yeIiwIcTKUE1W+4o81q8iuxQsXOC3yMlUoZJw51rd2ZXRkgI43CXVRHK2 Ga8QJ2th2fcnSa8ibq3gzo5iYj8GyS/amKx8p+fhWtQGzfNi9mVMeI6ujhMJNp9K l1nY7ILkAlVeGV/bw3tpqhehPYIjPzA/878nFR/gae8tTeewXGwMZalyxnWgJ5b8 4MrOnzxxZ8jJGECaunvM2VwZXZrDFPM/b+vqnxPIWvNoCl+4PC5+gtMDgmsTqyp4 MrUeY0OSmxXpjJrJEXqAqlzppElof2ocMhHQfszqF2yA3KHwUKM= =za8D -----END PGP SIGNATURE----- --HlL+5n6rz5pIUxbD--
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