READLINK(2) System Calls READLINK(2)

readlink - read the contents of a symbolic link

#include <unistd.h>
ssize_t readlink(const char *restrict path,
     char *restrict buf, size_t bufsiz);

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

The readlink() and readlinkat() functions place the contents of the symbolic link referred to by path in the buffer buf which has size bufsiz. If the number of bytes in the symbolic link is less than bufsiz, the contents of the remainder of buf are left unchanged. If the buf argument is not large enough to contain the link content, the first bufsize bytes are placed in buf.

The realinkat() function behaves similarly to readlink(); however, when path is a relative path, it is resolved relative to the directory referred to by fd. To use the current working directory, fd should be the special value AT_FDCWD.

Upon successful completion, readlink() and readlinkat() return the count of bytes placed in the buffer. Otherwise, they returns −1, leave the buffer unchanged, and set errno to indicate the error.

The readlink() and readlinkat() functions will fail if:


Search permission is denied for a component of the path prefix of path.


path or buf points to an illegal address.


The path argument names a file that is not a symbolic link.


An I/O error occurred while reading from the file system.


A component of path does not name an existing file or path is an empty string.


A loop exists in symbolic links encountered during resolution of the path argument.


The length of path exceeds {PATH_MAX}, or a pathname component is longer than {NAME_MAX} while _POSIX_NO_TRUNC is in effect.


A component of the path prefix is not a directory. For readlinkat(), if path is a relative path and fd refers to a valid file descriptor which is not a directory.


The file system does not support symbolic links.

The readlinkat() function will fail if:


The path argument is a relative path and fd is not a valid, open file descriptor or the special value AT_FDCWD.

The readlink() function may fail if:


Read permission is denied for the directory.


More than {SYMLOOP_MAX} symbolic links were encountered in resolving path.


As a result of encountering a symbolic link in resolution of the path argument, the length of the substituted pathname string exceeded {PATH_MAX}.

Portable applications should not assume that the returned contents of the symbolic link are null-terminated.

See attributes(7) for descriptions of the following attributes:

Interface Stability Standard
MT-Level Async-Signal-Safe

stat(2), symlink(2), attributes(7), standards(7)
December 23, 2014 OmniOS