realpath (3)
Leading comments
Copyright (C) 1999 Andries Brouwer (aeb@cwi.nl) %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the L...
NAME
realpath - return the canonicalized absolute pathnameSYNOPSIS
#include <limits.h> #include <stdlib.h> char *realpath(const char *path, char *resolved_path);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
realpath():
- _BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
DESCRIPTION
realpath() expands all symbolic links and resolves references to /./, /../ and extra aq/aq characters in the null-terminated string named by path to produce a canonicalized absolute pathname. The resulting pathname is stored as a null-terminated string, up to a maximum of PATH_MAX bytes, in the buffer pointed to by resolved_path. The resulting path will have no symbolic link, /./ or /../ components.If resolved_path is specified as NULL, then realpath() uses malloc(3) to allocate a buffer of up to PATH_MAX bytes to hold the resolved pathname, and returns a pointer to this buffer. The caller should deallocate this buffer using free(3).
RETURN VALUE
If there is no error, realpath() returns a pointer to the resolved_path.Otherwise, it returns NULL, the contents of the array resolved_path are undefined, and errno is set to indicate the error.
ERRORS
- EACCES
- Read or search permission was denied for a component of the path prefix.
- EINVAL
- path is NULL. (In glibc versions before 2.3, this error is also returned if resolved_path is NULL.)
- EIO
- An I/O error occurred while reading from the filesystem.
- ELOOP
- Too many symbolic links were encountered in translating the pathname.
- ENAMETOOLONG
- A component of a pathname exceeded NAME_MAX characters, or an entire pathname exceeded PATH_MAX characters.
- ENOMEM
- Out of memory.
- ENOENT
- The named file does not exist.
- ENOTDIR
- A component of the path prefix is not a directory.
ATTRIBUTES
For an explanation of the terms used in this section, see attributes(7).| Interface | Attribute | Value |
| realpath() | Thread safety | MT-Safe |
CONFORMING TO
4.4BSD, POSIX.1-2001.POSIX.1-2001 says that the behavior if resolved_path is NULL is implementation-defined. POSIX.1-2008 specifies the behavior described in this page.
NOTES
In 4.4BSD and Solaris, the limit on the pathname length is MAXPATHLEN (found in <sys/param.h>). SUSv2 prescribes PATH_MAX and NAME_MAX, as found in <limits.h> or provided by the pathconf(3) function. A typical source fragment would be
#ifdef PATH_MAX
path_max = PATH_MAX;
#else
path_max = pathconf(path, _PC_PATH_MAX);
if (path_max <= 0)
path_max = 4096;
#endif
(But see the BUGS section.)