Updated: 2021/Apr/14

REALPATH(3)                Library Functions Manual                REALPATH(3)

     realpath - returns the canonicalized absolute pathname

     Standard C Library (libc, -lc)

     #include <sys/param.h>
     #include <stdlib.h>

     char *
     realpath(const char * restrict pathname, char * restrict resolvedname);

     The realpath() function resolves all symbolic links, extra "/" characters
     and references to /./ and /../ in pathname, and copies the resulting
     absolute pathname into the memory referenced by resolvedname.  The
     resolvedname argument must refer to a buffer capable of storing at least
     MAXPATHLEN characters, or be NULL.

     The realpath() function will resolve both absolute and relative paths and
     return the absolute pathname corresponding to pathname.

     If resolvedname is NULL, it will be allocated and the returned pointer
     can be deallocated using free(3).  The realpath() function returns
     resolvedname on success.  If an error occurs, realpath() returns NULL,
     and if resolvedname was not allocated by realpath(), it will contain the
     pathname which caused the problem.

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

     In addition, the following errors may be reported:

     [EINVAL]           The value of the pathname argument is NULL.

     [ELOOP]            Too many symbolic links were encountered in
                        translating the pathname.

     [ENAMETOOLONG]     The resulting absolute pathname exceeds MAXPATHLEN

     [ENOENT]           The value of the pathname argument is an empty string;
                        or a symbolic link to an empty string is encountered.

     [ENOTDIR]          A component of the path prefix is not a directory.


     realpath() first appeared in X/Open Portability Guide Issue 4, Version 2
     ("XPG4.2") and is part of IEEE Std 1003.1-2001 ("POSIX.1").

     The realpath() function call first appeared in 4.4BSD.  In NetBSD 7.0 the
     function was updated to accept a NULL pointer for the resolvedname

     This implementation of realpath() differs slightly from the Solaris
     implementation.  The 4.4BSD version always returns absolute pathnames,
     whereas the Solaris implementation will, under certain circumstances,
     return a relative resolvedname when given a relative pathname.

NetBSD 9.99                      May 24, 2013                      NetBSD 9.99