xref: /freebsd/usr.bin/head/head.1 (revision fd45b686f9d92f583366c75b22c04c7ee49709c0)
1.\" Copyright (c) 1980, 1990, 1993
2.\"	The Regents of the University of California.  All rights reserved.
3.\"
4.\" Redistribution and use in source and binary forms, with or without
5.\" modification, are permitted provided that the following conditions
6.\" are met:
7.\" 1. Redistributions of source code must retain the above copyright
8.\"    notice, this list of conditions and the following disclaimer.
9.\" 2. Redistributions in binary form must reproduce the above copyright
10.\"    notice, this list of conditions and the following disclaimer in the
11.\"    documentation and/or other materials provided with the distribution.
12.\" 3. Neither the name of the University nor the names of its contributors
13.\"    may be used to endorse or promote products derived from this software
14.\"    without specific prior written permission.
15.\"
16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26.\" SUCH DAMAGE.
27.\"
28.Dd June 12, 2022
29.Dt HEAD 1
30.Os
31.Sh NAME
32.Nm head
33.Nd display first lines of a file
34.Sh SYNOPSIS
35.Nm
36.Op Fl qv
37.Op Fl n Ar count | Fl c Ar bytes
38.Op Ar
39.Sh DESCRIPTION
40This filter displays the first
41.Ar count
42lines or
43.Ar bytes
44of each of the specified files, or of the standard input if no
45files are specified.
46If
47.Ar count
48is omitted it defaults to 10.
49.Pp
50The following options are available:
51.Bl -tag -width indent
52.It Fl c Ar bytes , Fl -bytes Ns = Ns Ar bytes
53Print
54.Ar bytes
55of each of the specified files.
56.It Fl n Ar count , Fl -lines Ns = Ns Ar count
57Print
58.Ar count
59lines of each of the specified files.
60.Pp
61Both
62.Ar count
63and
64.Ar bytes
65may also be specified with size suffixes supported by
66.Xr expand_number 3 .
67.It Fl q , Fl -quiet , Fl -silent
68Suppresses printing of headers when multiple files are being examined.
69.It Fl v , Fl -verbose
70Prepend each file with a header.
71.El
72.Pp
73If more than a single file is specified, or if the
74.Fl v
75option is used, each file is preceded by a
76header consisting of the string
77.Dq ==> XXX <==
78where
79.Dq XXX
80is the name of the file.
81The
82.Fl q
83flag disables the printing of the header in all cases.
84.Sh EXIT STATUS
85.Ex -std
86.Sh EXAMPLES
87To display the first 500 lines of the file
88.Ar foo :
89.Pp
90.Dl $ head -n 500 foo
91.Pp
92.Nm
93can be used in conjunction with
94.Xr tail 1
95in the following way to, for example, display only line 500 from the file
96.Ar foo :
97.Pp
98.Dl $ head -n 500 foo | tail -n 1
99.Sh SEE ALSO
100.Xr tail 1 ,
101.Xr expand_number 3
102.Sh HISTORY
103The
104.Nm
105command appeared in PWB UNIX.
106