realpath(S-osr5)

realpath -- returns the real file name

Syntax

cc ...-lc

#include <stdlib.h>

char *realpath (const char *file_name, char *resolved_name);

Description

realpath(S-osr5) resolves all links, symbolic links, and references to ``.'' and ``..'' in file_name and stores the path in resolved_name. It can handle both relative and absolute path names:

For absolute path names and the relative names whose resolved name cannot be expressed relatively (for example, ../../reldir), it returns the resolved absolute name.
For the other relative path names, it returns the resolved relative name.

resolved_name must be big enough (MAXPATHLEN) to contain the fully resolved path name.

realpath( ) operates on null-terminated strings.

You should have execute permission on all the directories in the given and the resolved path.

If an error occurs, realpath( ) may fail to return to the current directory.

Return values

If there is no error, realpath( ) returns a pointer to the resolved_name. Otherwise it returns a null pointer and places the name of the offending file in resolved_name. The global variable errno is set to indicate the error.

Diagnostics

If any of the following conditions occur, this function returns -1 and sets errno to the corresponding value:

[EACCESS]: The system denied you read or search permission for some part of file_name.
[EINVAL]: One of the arguments file_name or resolved_name is a null pointer.
[EIO]: The function encountered an I/O error while reading from the file system.
[ELOOP]: The function found too many symbolic links while resolving the path.
[ENAMETOOLONG]: Either file_name or a component of the path name is longer than PATH_MAX bytes.
[ENOENT]: Either a component of file_name does not exist or file_name points to an empty string.
[ENOTDIR]: Part of the pathname prefix is not a directory.

The following conditions might cause the function to fail:

[ENAMETOOLONG]: Resolving a symbolic link in the pathname produced an intermediate result that is longer than PATH_MAX bytes.
[ENOMEM]: There is not enough memory.

Standards conformance

realpath(S-osr5) is conformant with