1.\" Copyright (c) 1980, 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the Institute of Electrical and Electronics Engineers, Inc. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)tail.1 8.1 (Berkeley) 6/6/93 36.\" 37.Dd June 6, 1993 38.Dt TAIL 1 39.Os BSD 4 40.Sh NAME 41.Nm tail 42.Nd display the last part of a file 43.Sh SYNOPSIS 44.Nm tail 45.Op Fl f Li | Fl r 46.Oo 47.Fl b Ar number | 48.Fl c Ar number | 49.Fl n Ar number 50.Oc 51.Op Ar file ... 52.Sh DESCRIPTION 53The 54.Nm tail 55utility displays the contents of 56.Ar file 57or, by default, its standard input, to the standard output. 58.Pp 59The display begins at a byte, line or 512-byte block location in the 60input. 61Numbers having a leading plus (``+'') sign are relative to the beginning 62of the input, for example, 63.Dq -c +2 64starts the display at the second 65byte of the input. 66Numbers having a leading minus (``-'') sign or no explicit sign are 67relative to the end of the input, for example, 68.Dq -n 2 69displays the last two lines of the input. 70The default starting location is 71.Dq -n 10 , 72or the last 10 lines of the input. 73.Pp 74The options are as follows: 75.Bl -tag -width Ds 76.It Fl b Ar number 77The location is 78.Ar number 79512-byte blocks. 80.It Fl c Ar number 81The location is 82.Ar number 83bytes. 84.It Fl f 85The 86.Fl f 87option causes 88.Nm tail 89to not stop when end of file is reached, but rather to wait for additional 90data to be appended to the input. 91The 92.Fl f 93option is ignored if the standard input is a pipe, but not if it is a FIFO. 94.It Fl n Ar number 95The location is 96.Ar number 97lines. 98.It Fl r 99The 100.Fl r 101option causes the input to be displayed in reverse order, by line. 102Additionally, this option changes the meaning of the 103.Fl b , 104.Fl c 105and 106.Fl n 107options. 108When the 109.Fl r 110option is specified, these options specify the number of bytes, lines 111or 512-byte blocks to display, instead of the bytes, lines or blocks 112from the beginning or end of the input from which to begin the display. 113The default for the 114.Fl r 115option is to display all of the input. 116.El 117.Pp 118If more than a single file is specified, each file is preceded by a 119header consisting of the string 120.Dq ==> XXX <== 121where 122.Dq XXX 123is the name of the file. 124.Pp 125The 126.Nm tail 127utility exits 0 on success, and >0 if an error occurs. 128.Sh SEE ALSO 129.Xr cat 1 , 130.Xr head 1 , 131.Xr sed 1 132.Sh STANDARDS 133The 134.Nm tail 135utility is expected to be a superset of the POSIX 1003.2 136specification. 137In particular, the 138.Fl b 139and 140.Fl r 141options are extensions to that standard. 142.Pp 143The historic command line syntax of 144.Nm tail 145is supported by this implementation. 146The only difference between this implementation and historic versions 147of 148.Nm tail , 149once the command line syntax translation has been done, is that the 150.Fl b , 151.Fl c 152and 153.Fl n 154options modify the 155.Fl r 156option, i.e. ``-r -c 4'' displays the last 4 characters of the last line 157of the input, while the historic tail (using the historic syntax ``-4cr'') 158would ignore the 159.Fl c 160option and display the last 4 lines of the input. 161.Sh HISTORY 162A 163.Nm tail 164command appeared in 165.At v7 . 166