xref: /freebsd/lib/libc/gen/dirname.3 (revision 938809f9411ca770cd11d6e96fb384050a52f7d8)
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.
8.\"
9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16.\"
17.\" $FreeBSD$
18.\"
19.Dd July 28, 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.
40If
41.Fa path
42is a null pointer, the empty string, or contains no
43.Sq \&/
44characters,
45.Fn dirname
46returns a pointer to the string
47.Qq \&. ,
48signifying the current directory.
49.Sh IMPLEMENTATION NOTES
50The
51.Fn dirname
52function
53returns a pointer to internal storage space allocated on the first call
54that will be overwritten
55by subsequent calls.
56.Pp
57Other vendor implementations of
58.Fn dirname
59may modify the contents of the string passed to
60.Fn dirname ;
61this should be taken into account when writing code which calls this function
62if portability is desired.
63.Sh RETURN VALUES
64On successful completion,
65.Fn dirname
66returns a pointer to the parent directory of
67.Fa path .
68.Pp
69If
70.Fn dirname
71fails, a null pointer is returned and the global variable
72.Va errno
73is set to indicate the error.
74.Sh ERRORS
75The following error codes may be set in
76.Va errno :
77.Bl -tag -width Er
78.It Bq Er ENAMETOOLONG
79The path component to be returned was larger than
80.Dv MAXPATHLEN .
81.El
82.Sh SEE ALSO
83.Xr basename 1 ,
84.Xr dirname 1 ,
85.Xr basename 3
86.Sh STANDARDS
87The
88.Fn dirname
89function conforms to
90.St -xpg4.2 .
91.Sh HISTORY
92The
93.Fn dirname
94function first appeared in
95.Ox 2.2
96and
97.Fx 4.2 .
98.Sh AUTHORS
99.An "Todd C. Miller"
100