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1 | .\" Copyright (c) 1980, 1990, 1991 Regents of the University of California. |
2 | .\" 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 6.8 (Berkeley) 2/12/92 | |
36 | .\" | |
37 | .Dd February 12, 1992 | |
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 | |
53 | The | |
54 | .Nm tail | |
55 | utility displays the contents of | |
56 | .Ar file | |
57 | or, by default, its standard input, to the standard output. | |
58 | .Pp | |
59 | The display begins at a byte, line or 512-byte block location in the | |
60 | input. | |
61 | Numbers having a leading plus (``+'') sign are relative to the beginning | |
62 | of the input, for example, | |
63 | .Dq -c +2 | |
64 | starts the display at the second | |
65 | byte of the input. | |
66 | Numbers having a leading minus (``-'') sign or no explicit sign are | |
67 | relative to the end of the input, for example, | |
68 | .Dq -n 2 | |
69 | displays the last two lines of the input. | |
70 | The default starting location is | |
71 | .Dq -n 10 , | |
72 | or the last 10 lines of the input. | |
73 | .Pp | |
74 | The options are as follows: | |
75 | .Bl -tag -width Ds | |
76 | .It Fl b Ar number | |
77 | The location is | |
78 | .Ar number | |
15637ed4 | 79 | 512-byte blocks. |
d8ae9abd NW |
80 | .It Fl c Ar number |
81 | The location is | |
82 | .Ar number | |
83 | bytes. | |
84 | .It Fl f | |
85 | The | |
86 | .Fl f | |
87 | option causes | |
88 | .Nm tail | |
89 | to not stop when end of file is reached, but rather to wait for additional | |
90 | data to be appended to the input. | |
91 | The | |
92 | .Fl f | |
93 | option is ignored on pipes but not on FIFO's. | |
94 | .It Fl n Ar number | |
95 | The location is | |
96 | .Ar number | |
97 | lines. | |
98 | .It Fl r | |
99 | The | |
100 | .Fl r | |
101 | option causes the input to be displayed in reverse order, by line. | |
102 | Additionally, this option changes the meaning of the | |
103 | .Fl b , | |
104 | .Fl c | |
105 | and | |
106 | .Fl n | |
107 | options. | |
108 | When the | |
109 | .Fl r | |
110 | option is specified, these options specify the number of bytes, lines | |
111 | or 512-byte blocks to display, instead of the bytes, lines or blocks | |
112 | from the beginning or end of the input from which to begin the display. | |
113 | The default for the | |
114 | .Fl r | |
115 | option is to display all of the input. | |
116 | .El | |
117 | .Pp | |
118 | The | |
119 | .Nm tail | |
120 | utility exits 0 on success, and >0 if an error occurs. | |
121 | .Sh SEE ALSO | |
122 | .Xr cat 1 , | |
123 | .Xr head 1 , | |
124 | .Xr sed 1 | |
125 | .Sh STANDARDS | |
126 | The | |
127 | .Nm tail | |
128 | utility is expected to be a superset of the POSIX 1003.2 | |
129 | specification. | |
130 | In particular, the | |
131 | .Fl b | |
132 | and | |
133 | .Fl r | |
134 | options are extensions to that standard. | |
135 | .Pp | |
136 | The historic command line syntax of | |
137 | .Nm tail | |
138 | is supported by this implementation. | |
139 | The only difference between this implementation and historic versions | |
140 | of | |
141 | .Nm tail , | |
142 | once the command line syntax translation has been done, is that the | |
143 | .Fl b , | |
144 | .Fl c | |
145 | and | |
146 | .Fl n | |
147 | options modify the | |
148 | .Fl r | |
149 | option, i.e. ``-r -c 4'' displays the last 4 characters of the last line | |
150 | of the input, while the historic tail (using the historic syntax ``-4cr'') | |
151 | would ignore the | |
152 | .Fl c | |
153 | option and display the last 4 lines of the input. | |
154 | .Sh HISTORY | |
155 | A | |
156 | .Nm tail | |
157 | command appeared in | |
158 | .At v7 . |