realpath (3) - Linux Man Pages
realpath: return the canonicalized absolute pathname
realpath - return the canonicalized absolute pathname
#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)):
_XOPEN_SOURCE >= 500
|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
DESCRIPTIONrealpath() expands all symbolic links and resolves references to /./, /../ and extra '/' 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 VALUEIf there is no error, realpath() returns a pointer to the resolved_path.
- Read or search permission was denied for a component of the path prefix.
- path is NULL. (In glibc versions before 2.3, this error is also returned if resolved_path is NULL.)
- An I/O error occurred while reading from the filesystem.
- Too many symbolic links were encountered in translating the pathname.
- A component of a pathname exceeded NAME_MAX characters, or an entire pathname exceeded PATH_MAX characters.
- The named file does not exist.
- Out of memory.
- A component of the path prefix is not a directory.
ATTRIBUTESFor an explanation of the terms used in this section, see attributes(7).
CONFORMING TO4.4BSD, POSIX.1-2001.
NOTESIn 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
(But see the BUGS section.)
If the call fails with either
is not NULL, then the prefix of
that is not readable or does not exist is returned in
The POSIX.1-2001 standard version of this function is broken by design,
since it is impossible to determine a suitable size for the output buffer,
According to POSIX.1-2001 a buffer of size
need not be a defined constant, and may have to be obtained using
does not really help, since, on the one hand POSIX warns that
the result of
may be huge and unsuitable for mallocing memory,
and on the other hand
may return -1 to signify that
is not bounded.
resolved_path == NULL
feature, not standardized in POSIX.1-2001,
but standardized in POSIX.1-2008, allows this design problem to be avoided.
This page is part of release 5.05 of the Linux
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
(But see the BUGS section.)