NAME
readlink
,
readlinkat
—
read value of a symbolic
link
SYNOPSIS
#include
<unistd.h>
ssize_t
readlink
(const
char *restrict path, char
*restrict buf, size_t
bufsiz);
#include <fcntl.h>
#include <unistd.h>
ssize_t
readlinkat
(int
fd, const char
*path, char *buf,
size_t bufsiz);
DESCRIPTION
The
readlink
()
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
readlinkat
()
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
readlinkat
()
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
().
RETURN VALUES
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.
ERRORS
readlink
() and
readlinkat
() will fail if:
- [
ENOTDIR
] - A component of the path prefix is not a directory.
- [
ENAMETOOLONG
] - A component of a pathname exceeded
NAME_MAX
characters, or an entire pathname (including the terminating NUL) exceededPATH_MAX
bytes. - [
ENOENT
] - The named file does not exist.
- [
EACCES
] - Search permission is denied for a component of the path prefix.
- [
ELOOP
] - Too many symbolic links were encountered in translating the pathname.
- [
EINVAL
] - The named file is not a symbolic link.
- [
EIO
] - An I/O error occurred while reading from the file system.
- [
EFAULT
] - buf or path extends outside the process's allocated address space.
Additionally, readlinkat
() will fail
if:
- [
EBADF
] - The path argument specifies a relative path and the
fd argument is neither
AT_FDCWD
nor a valid file descriptor. - [
ENOTDIR
] - The path argument specifies a relative path and the fd argument is a valid file descriptor but it does not reference a directory.
- [
EACCES
] - The path argument specifies a relative path but search permission is denied for the directory which the fd file descriptor references.
SEE ALSO
STANDARDS
The readlink
() and
readlinkat
() functions conform to
IEEE Std 1003.1-2008 (“POSIX.1”).
HISTORY
The readlink
() system call first appeared
in 4.1cBSD. The readlinkat
()
system call has been available since OpenBSD
5.0.