1REALPATH(3P) POSIX Programmer's Manual REALPATH(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 realpath - resolve a pathname
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15 #include <stdlib.h>
16 char *realpath(const char *restrict file_name,
18 char *restrict resolved_name);
19
22 The realpath() function shall derive, from the pathname pointed to by
23 file_name, an absolute pathname that names the same file, whose resolu‐
24 tion does not involve '.', '..', or symbolic links. The generated path‐
25 name shall be stored as a null-terminated string, up to a maximum of
26 {PATH_MAX} bytes, in the buffer pointed to by resolved_name.
27 If resolved_name is a null pointer, the behavior of realpath() is
29 implementation-defined.
30
32 Upon successful completion, realpath() shall return a pointer to the
33 resolved name. Otherwise, realpath() shall return a null pointer and
34 set errno to indicate the error, and the contents of the buffer pointed
35 to by resolved_name are undefined.
36
38 The realpath() function shall fail if:
39 EACCES Read or search permission was denied for a component of
41 file_name.
42 EINVAL The file_name argument is a null pointer.
44 EIO An error occurred while reading from the file system.
46 ELOOP A loop exists in symbolic links encountered during resolution of
48 the path argument.
49 ENAMETOOLONG
51 The length of the file_name argument exceeds {PATH_MAX} or a
52 pathname component is longer than {NAME_MAX}.
53 ENOENT A component of file_name does not name an existing file or
55 file_name points to an empty string.
56 ENOTDIR
58 A component of the path prefix is not a directory.
59 The realpath() function may fail if:
62 ELOOP More than {SYMLOOP_MAX} symbolic links were encountered during
64 resolution of the path argument.
65 ENAMETOOLONG
67 Pathname resolution of a symbolic link produced an intermediate
68 result whose length exceeds {PATH_MAX}.
69 ENOMEM Insufficient storage space is available.
71 The following sections are informative.
74
76 Generating an Absolute Pathname
77 The following example generates an absolute pathname for the file iden‐
78 tified by the symlinkpath argument. The generated pathname is stored in
79 the actualpath array.
80 #include <stdlib.h>
83 ...
84 char *symlinkpath = "/tmp/symlink/file";
85 char actualpath [PATH_MAX+1];
86 char *ptr;
87 ptr = realpath(symlinkpath, actualpath);
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92 None.
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95 Since the maximum pathname length is arbitrary unless {PATH_MAX} is
96 defined, an application generally cannot supply a resolved_name buffer
97 with size {{PATH_MAX}+1}.
98
100 In the future, passing a null pointer to realpath() for the
101 resolved_name argument may be defined to have realpath() allocate space
102 for the generated pathname.
103
105 getcwd(), sysconf(), the Base Definitions volume of
106 IEEE Std 1003.1-2001, <stdlib.h>
107
109 Portions of this text are reprinted and reproduced in electronic form
110 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
111 -- Portable Operating System Interface (POSIX), The Open Group Base
112 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
113 Electrical and Electronics Engineers, Inc and The Open Group. In the
114 event of any discrepancy between this version and the original IEEE and
115 The Open Group Standard, the original IEEE and The Open Group Standard
116 is the referee document. The original Standard can be obtained online
117 at http://www.opengroup.org/unix/online.html .
118IEEE/The Open Group 2003 REALPATH(3P)