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READLINK(2) System Calls Manual READLINK(2)

readlink, readlinkatread value of a symbolic link

#include <fcntl.h>
#include <unistd.h>

readlink(const char *path, char *buf, size_t bufsiz);

readlinkat(int fd, const char *path, char *buf, size_t bufsiz);

The () function places the contents of the symbolic link path in the buffer buf, which has size bufsiz. readlink does not append a NUL character to buf.

The () function is equivalent to readlink() except that where path specifies a relative path, the symbolic link whose contents are read is determined relative to the directory associated with file descriptor fd instead of the current working directory.

If () is passed the special value AT_FDCWD (defined in <fcntl.h>) in the fd parameter, the current working directory is used and the behavior is identical to a call to readlink().

The call returns the count of characters placed in the buffer if it succeeds, or a -1 if an error occurs, placing the error code in the global variable errno.

readlink() and readlinkat() will fail if:

A component of the path prefix is not a directory.
A component of a pathname exceeded {NAME_MAX} characters, or an entire path name exceeded {PATH_MAX} characters.
The named file does not exist.
Search permission is denied for a component of the path prefix.
Too many symbolic links were encountered in translating the pathname.
The named file is not a symbolic link.
An I/O error occurred while reading from the file system.
buf or path extends outside the process's allocated address space.

Additionally, readlinkat() will fail if:

The path argument does not specify an absolute path and the fd argument is neither AT_FDCWD nor a valid file descriptor open for reading.

lstat(2), stat(2), symlink(2), symlink(7)

The readlink() and readlinkat() functions conform to IEEE Std 1003.1-2008 (“POSIX.1”).

The readlink() function call appeared in 4.2BSD. The readlinkat() function call appeared in OpenBSD 5.0.

July 18, 2011 OpenBSD-5.1