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 45.Oo 46.Fl F | 47.Fl f | 48.Fl r 49.Oc 50.Oo 51.Fl b Ar number | 52.Fl c Ar number | 53.Fl n Ar number 54.Oc 55.Op Ar 56.Sh DESCRIPTION 57The 58.Nm 59utility displays the contents of 60.Ar file 61or, by default, its standard input, to the standard output. 62.Pp 63The display begins at a byte, line or 512-byte block location in the 64input. 65Numbers having a leading plus (``+'') sign are relative to the beginning 66of the input, for example, 67.Dq -c +2 68starts the display at the second 69byte of the input. 70Numbers having a leading minus (``-'') sign or no explicit sign are 71relative to the end of the input, for example, 72.Dq -n 2 73displays the last two lines of the input. 74The default starting location is 75.Dq -n 10 , 76or the last 10 lines of the input. 77.Pp 78The options are as follows: 79.Bl -tag -width Ds 80.It Fl b Ar number 81The location is 82.Ar number 83512-byte blocks. 84.It Fl c Ar number 85The location is 86.Ar number 87bytes. 88.It Fl f 89The 90.Fl f 91option causes 92.Nm 93to not stop when end of file is reached, but rather to wait for additional 94data to be appended to the input. 95The 96.Fl f 97option is ignored if the standard input is a pipe, but not if it is a FIFO. 98.It Fl F 99The 100.Fl F 101option implies the 102.Fl f 103option, but 104.Nm 105will also check to see if the file being followed has been renamed or rotated. 106The file is closed and reopened when 107.Nm 108detects that the filename being read from has a new inode number. 109The 110.Fl F 111option is ignored if reading from standard input rather than a file. 112.It Fl n Ar number 113The location is 114.Ar number 115lines. 116.It Fl r 117The 118.Fl r 119option causes the input to be displayed in reverse order, by line. 120Additionally, this option changes the meaning of the 121.Fl b , 122.Fl c 123and 124.Fl n 125options. 126When the 127.Fl r 128option is specified, these options specify the number of bytes, lines 129or 512-byte blocks to display, instead of the bytes, lines or blocks 130from the beginning or end of the input from which to begin the display. 131The default for the 132.Fl r 133option is to display all of the input. 134.El 135.Pp 136If more than a single file is specified, each file is preceded by a 137header consisting of the string 138.Dq ==> XXX <== 139where 140.Dq XXX 141is the name of the file. 142.Pp 143The 144.Nm 145utility exits 0 on success, and >0 if an error occurs. 146.Sh SEE ALSO 147.Xr cat 1 , 148.Xr head 1 , 149.Xr sed 1 150.Sh STANDARDS 151The 152.Nm 153utility is expected to be a superset of the 154.St -p1003.2-92 155specification. 156In particular, the 157.Fl F , 158.Fl b 159and 160.Fl r 161options are extensions to that standard. 162.Pp 163The historic command line syntax of 164.Nm 165is supported by this implementation. 166The only difference between this implementation and historic versions 167of 168.Nm tail , 169once the command line syntax translation has been done, is that the 170.Fl b , 171.Fl c 172and 173.Fl n 174options modify the 175.Fl r 176option, i.e. ``-r -c 4'' displays the last 4 characters of the last line 177of the input, while the historic tail (using the historic syntax ``-4cr'') 178would ignore the 179.Fl c 180option and display the last 4 lines of the input. 181.Sh HISTORY 182A 183.Nm 184command appeared in 185.At v7 . 186