1.\" $OpenBSD: tail.1,v 1.2 1996/06/26 05:40:17 deraadt Exp $ 2.\" $NetBSD: tail.1,v 1.4 1994/11/23 07:42:13 jtc Exp $ 3.\" 4.\" Copyright (c) 1980, 1990, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" This code is derived from software contributed to Berkeley by 8.\" the Institute of Electrical and Electronics Engineers, Inc. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.\" @(#)tail.1 8.1 (Berkeley) 6/6/93 39.\" 40.Dd June 6, 1993 41.Dt TAIL 1 42.Os BSD 4 43.Sh NAME 44.Nm tail 45.Nd display the last part of a file 46.Sh SYNOPSIS 47.Nm tail 48.Op Fl f Li | Fl r 49.Oo 50.Fl b Ar number | 51.Fl c Ar number | 52.Fl n Ar number 53.Oc 54.Op Ar file ... 55.Sh DESCRIPTION 56The 57.Nm tail 58utility displays the contents of 59.Ar file 60or, by default, its standard input, to the standard output. 61.Pp 62The display begins at a byte, line or 512-byte block location in the 63input. 64Numbers having a leading plus (``+'') sign are relative to the beginning 65of the input, for example, 66.Dq -c +2 67starts the display at the second 68byte of the input. 69Numbers having a leading minus (``-'') sign or no explicit sign are 70relative to the end of the input, for example, 71.Dq -n 2 72displays the last two lines of the input. 73The default starting location is 74.Dq -n 10 , 75or the last 10 lines of the input. 76.Pp 77The options are as follows: 78.Bl -tag -width Ds 79.It Fl b Ar number 80The location is 81.Ar number 82512-byte blocks. 83.It Fl c Ar number 84The location is 85.Ar number 86bytes. 87.It Fl f 88The 89.Fl f 90option causes 91.Nm tail 92to not stop when end of file is reached, but rather to wait for additional 93data to be appended to the input. 94The 95.Fl f 96option is ignored if the standard input is a pipe, but not if it is a FIFO. 97.It Fl n Ar number 98The location is 99.Ar number 100lines. 101.It Fl r 102The 103.Fl r 104option causes the input to be displayed in reverse order, by line. 105Additionally, this option changes the meaning of the 106.Fl b , 107.Fl c 108and 109.Fl n 110options. 111When the 112.Fl r 113option is specified, these options specify the number of bytes, lines 114or 512-byte blocks to display, instead of the bytes, lines or blocks 115from the beginning or end of the input from which to begin the display. 116The default for the 117.Fl r 118option is to display all of the input. 119.El 120.Pp 121If more than a single file is specified, each file is preceded by a 122header consisting of the string 123.Dq ==> XXX <== 124where 125.Dq XXX 126is the name of the file. 127.Pp 128The 129.Nm tail 130utility exits 0 on success, and >0 if an error occurs. 131.Sh SEE ALSO 132.Xr cat 1 , 133.Xr head 1 , 134.Xr sed 1 135.Sh STANDARDS 136The 137.Nm tail 138utility is expected to be a superset of the 139.St -p1003.2-92 140specification. 141In particular, the 142.Fl b 143and 144.Fl r 145options are extensions to that standard. 146.Pp 147The historic command line syntax of 148.Nm tail 149is supported by this implementation. 150The only difference between this implementation and historic versions 151of 152.Nm tail , 153once the command line syntax translation has been done, is that the 154.Fl b , 155.Fl c 156and 157.Fl n 158options modify the 159.Fl r 160option, i.e. ``-r -c 4'' displays the last 4 characters of the last line 161of the input, while the historic tail (using the historic syntax ``-4cr'') 162would ignore the 163.Fl c 164option and display the last 4 lines of the input. 165.Sh HISTORY 166A 167.Nm tail 168command appeared in 169.At v7 . 170