NAME
readlink,
readlinkat —
read value of a symbolic
link
LIBRARY
library “libc”
SYNOPSIS
#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
bufsize);
DESCRIPTION
Thereadlink()
system call places the contents of the symbolic link
path in the buffer buf, which has
size bufsiz. The readlink()
system call does not append a NUL character to
buf.
The
readlinkat()
system call is equivalent to readlink() except in
the case where path specifies a relative path. In this
case the symbolic link whose content is read relative to the directory
associated with the file descriptor fd instead of the
current working directory. If readlinkat() is passed
the special value AT_FDCWD in the
fd parameter, the current working directory is used
and the behavior is identical to a call to
readlink().
RETURN VALUES
The calls return 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
The readlink() system call will fail
if:
- [
ENOTDIR] - A component of the path prefix is not a directory.
- [
ENAMETOOLONG] - A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.
- [
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] - The buf argument extends outside the process's allocated address space.
In addition to the errors returned by the
readlink(), the readlinkat()
may fail if:
- [
EBADF] - The path argument does not specify an absolute path
and the fd argument is neither
AT_FDCWDnor a valid file descriptor open for searching. - [
ENOTDIR] - The path argument is not an absolute path and
fd is neither
AT_FDCWDnor a file descriptor associated with a directory.
SEE ALSO
STANDARDS
The readlinkat() system call follows The
Open Group Extended API Set 2 specification.
HISTORY
The readlink() system call appeared in
4.2BSD. The readlinkat()
system call appeared in DragonFly 2.7.