REALPATH(3)

REALPATH(3) | Library Functions Manual | REALPATH(3)

# NAME

`realpath` — returns the canonicalized absolute pathname

# LIBRARY

Standard C Library (libc, -lc)

# SYNOPSIS

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

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

# DESCRIPTION

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.

# RETURN VALUES

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.

# ERRORS

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` characters.
[`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.

# SEE ALSO

getcwd(3)

# STANDARDS

`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”).

# HISTORY

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 argument.

# BUGS

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.

May 24, 2013 | NetBSD 11.0