REALPATH(3C) Standard C Library Functions REALPATH(3C)
realpath - resolve pathname
#include <stdlib.h>
char *realpath(const char *restrict file_name,
char *restrict resolved_name);
char *canonicalize_file_name(const char *path);
The realpath() function derives, from the pathname pointed to by
file_name, an absolute pathname that names the same file, whose
resolution does not involve ".", "..", or symbolic links. The
generated pathname is stored as a null-terminated string, up to a
maximum of {PATH_MAX} bytes (defined in limits.h(3HEAD)), in the
buffer pointed to by resolved_name.
The canonicalize_file_name() function is equivalent to calling
realpath(path, NULL). This function is only provided for
compatibility.
On successful completion, realpath() returns a pointer to the
resolved name. Otherwise, realpath() returns a null pointer and sets
errno to indicate the error, and the contents of the buffer pointed
to by resolved_name are left in an indeterminate state.
The realpath() function will fail if:
EACCES
Read or search permission was denied for a component
of file_name.
EINVAL
Either the file_name or resolved_name argument is a
null pointer.
EIO
An error occurred while reading from the file system.
ELOOP
Too many symbolic links were encountered in resolving
file_name.
ELOOP
A loop exists in symbolic links encountered during
resolution of the file_name argument.
ENAMETOOLONG
The file_name argument is longer than {PATH_MAX} or a
pathname component is longer than {NAME_MAX}.
ENOENT
A component of file_name does not name an existing
file or file_name points to an empty string.
ENOTDIR
A component of the path prefix is not a directory.
The realpath() function may fail if:
ENAMETOOLONG
Pathname resolution of a symbolic link produced an
intermediate result whose length exceeds {PATH_MAX}.
ENOMEM
Insufficient storage space is available.
The realpath() function operates on null-terminated strings.
Execute permission is required for all the directories in the given
and the resolved path.
The realpath() function might fail to return to the current directory
if an error occurs.
See attributes(7) for descriptions of the following attributes:
+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+
getcwd(3C), sysconf(3C), limits.h(3HEAD), attributes(7), standards(7)
December 20, 2014 REALPATH(3C)
NAME
realpath - resolve pathname
SYNOPSIS
#include <stdlib.h>
char *realpath(const char *restrict file_name,
char *restrict resolved_name);
char *canonicalize_file_name(const char *path);
DESCRIPTION
The realpath() function derives, from the pathname pointed to by
file_name, an absolute pathname that names the same file, whose
resolution does not involve ".", "..", or symbolic links. The
generated pathname is stored as a null-terminated string, up to a
maximum of {PATH_MAX} bytes (defined in limits.h(3HEAD)), in the
buffer pointed to by resolved_name.
The canonicalize_file_name() function is equivalent to calling
realpath(path, NULL). This function is only provided for
compatibility.
RETURN VALUES
On successful completion, realpath() returns a pointer to the
resolved name. Otherwise, realpath() returns a null pointer and sets
errno to indicate the error, and the contents of the buffer pointed
to by resolved_name are left in an indeterminate state.
ERRORS
The realpath() function will fail if:
EACCES
Read or search permission was denied for a component
of file_name.
EINVAL
Either the file_name or resolved_name argument is a
null pointer.
EIO
An error occurred while reading from the file system.
ELOOP
Too many symbolic links were encountered in resolving
file_name.
ELOOP
A loop exists in symbolic links encountered during
resolution of the file_name argument.
ENAMETOOLONG
The file_name argument is longer than {PATH_MAX} or a
pathname component is longer than {NAME_MAX}.
ENOENT
A component of file_name does not name an existing
file or file_name points to an empty string.
ENOTDIR
A component of the path prefix is not a directory.
The realpath() function may fail if:
ENAMETOOLONG
Pathname resolution of a symbolic link produced an
intermediate result whose length exceeds {PATH_MAX}.
ENOMEM
Insufficient storage space is available.
USAGE
The realpath() function operates on null-terminated strings.
Execute permission is required for all the directories in the given
and the resolved path.
The realpath() function might fail to return to the current directory
if an error occurs.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+
SEE ALSO
getcwd(3C), sysconf(3C), limits.h(3HEAD), attributes(7), standards(7)
December 20, 2014 REALPATH(3C)