xref: /freebsd/lib/libc/gen/dirname.3 (revision dd41de95a84d979615a2ef11df6850622bf6184e)
1.\" $OpenBSD: dirname.3,v 1.17 2007/05/31 19:19:28 jmc Exp $
2.\"
3.\" Copyright (c) 1997 Todd C. Miller <Todd.Miller@courtesan.com>
4.\"
5.\" Permission to use, copy, modify, and distribute this software for any
6.\" purpose with or without fee is hereby granted, provided that the above
7.\" copyright notice and this permission notice appear in all copies.
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9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16.\"
17.\" $FreeBSD$
18.\"
19.Dd September 5, 2016
20.Dt DIRNAME 3
21.Os
22.Sh NAME
23.Nm dirname
24.Nd extract the directory part of a pathname
25.Sh SYNOPSIS
26.In libgen.h
27.Ft char *
28.Fn dirname "char *path"
29.Sh DESCRIPTION
30The
31.Fn dirname
32function is the converse of
33.Xr basename 3 ;
34it returns a pointer to the parent directory of the pathname pointed to by
35.Fa path .
36Any trailing
37.Sq \&/
38characters are not counted as part of the directory
39name.
40.Sh IMPLEMENTATION NOTES
41This implementation of
42.Fn dirname
43uses the buffer provided by the caller to store the resulting parent
44directory.
45Other vendor implementations may return a pointer to internal storage
46space instead.
47The advantage of the former approach is that it ensures thread-safety,
48while also placing no upper limit on the supported length of the
49pathname.
50.Sh RETURN VALUES
51If
52.Fa path
53is a null pointer, the empty string, or contains no
54.Sq \&/
55characters,
56.Fn dirname
57returns a pointer to the string
58.Qq \&. ,
59signifying the current directory.
60Otherwise,
61it returns a pointer to the parent directory of
62.Fa path .
63.Sh SEE ALSO
64.Xr basename 1 ,
65.Xr dirname 1 ,
66.Xr basename 3
67.Sh STANDARDS
68The
69.Fn dirname
70function conforms to
71.St -xpg4.2 .
72.Sh HISTORY
73The
74.Fn dirname
75function first appeared in
76.Ox 2.2
77and
78.Fx 4.2 .
79.Pp
80In
81.Fx 12.0 ,
82this function was reimplemented to store its result in the provided
83input buffer.
84.Sh AUTHORS
85.An Nuxi, the Netherlands
86