realpath(3) - Useful Manual Pages

NAME

realpath — returns the canonicalized absolute pathname

SYNOPSIS

#include <stdlib.h>

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

The realpath() function resolves all symbolic links, extra “/” characters, and references to /./ and /../ in file_name. If the resolved_name argument is non-NULL, the resulting absolute pathname is copied there (it must refer to a buffer capable of storing at least PATH_MAX characters).

As a permitted extension to the standard, if resolved_name is NULL, memory is allocated for the resulting absolute pathname, and is returned by realpath(). This memory should be freed by a call to free(3) when no longer needed.

The realpath() function will resolve both absolute and relative paths and return the absolute pathname corresponding to file_name. All components of file_name must exist when realpath() is called.

RETURN VALUES

On success, the realpath() function returns the address of the resulting absolute pathname, which is resolved_name if it was non-NULL, or the address of newly allocated memory. If an error occurs, realpath() returns NULL. If resolved_name was non-NULL, it will contain the pathname which caused the problem.

VARIANTS

Defining _DARWIN_C_SOURCE or _DARWIN_BETTER_REALPATH before including stdlib.h will cause the provided implementation of realpath() to use F_GETPATH from fcntl(2) to discover the path.

ERRORS

The function realpath() may fail and set the external variable errno for any of the errors specified for the library functions alloca(3), getattrlist(2), getcwd(3), lstat(2), readlink(2), stat(2), and strdup(3).