const char *file_name,
Interfaces documented on this reference page conform to industry standards as follows:
realpath(): POSIX.1, XPG4-UNIX
Refer to the standards(5) reference page for more information about industry standards and associated tags.
The realpath() function derives, from the file 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, up to a maximum of PATH_MAX bytes, in the buffer pointed to by resolved_name.
Upon successful completion, the realpath() function 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 undefined.
If the realpath() function fails, errno may be set to one of the following values: Read or search permission was denied for a component of file_name. Either the file_name or resolved_name argument is a null pointer. An error occurred while reading from the file system. Too many symbolic links were encountered in resolving path. The file_name argument is longer than PATH_MAX or a pathname component is longer than NAME_MAX. A component of file_name does not name an existing file or file_name points to an empty string. Insufficient storage space available. A component of either path prefix is not a directory.
Functions: getcwd(3), sysconf(3)
Standards: standards(5) delim off