unlink(2) - NetBSD Manual Pages

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UNLINK(2)                 NetBSD System Calls Manual                 UNLINK(2)


NAME

     unlink, unlinkat -- remove directory entry


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <unistd.h>

     int
     unlink(const char *path);

     #include <fcntl.h>

     int
     unlinkat(int fd, const char *path, int flag);


DESCRIPTION

     The unlink() function removes the link named by path from its directory
     and decrements the link count of the file which was referenced by the
     link.  If that decrement reduces the link count of the file to zero, and
     no process has the file open, then all resources associated with the file
     are reclaimed.  If one or more process have the file open when the last
     link is removed, the link is removed, but the removal of the file is
     delayed until all references to it have been closed.

     unlinkat() works the same way as unlink() except if path is relative.  In
     that case, it is looked up from a directory whose file descriptor was
     passed as fd.  Search permission is required on this directory.  fd can
     be set to AT_FDCWD in order to specify the current directory.

     unlinkat() will remove directories just like rmdir(2), provided
     AT_REMOVEDIR is set in flag.


RETURN VALUES

     The unlink() and unlinkat() functions return the value 0 if successful;
     otherwise the value -1 is returned and the global variable errno is set
     to indicate the error.


ERRORS

     The unlink() and unlinkat() functions succeed unless:

     [EACCES]           Search permission is denied for a component of the
                        path prefix, or write permission is denied on the
                        directory containing the link to be removed.

     [EBUSY]            The entry to be unlinked is the mount point for a
                        mounted file system.

     [EFAULT]           path points outside the process's allocated address
                        space.

     [EIO]              An I/O error occurred while deleting the directory
                        entry or deallocating the inode.

     [ELOOP]            Too many symbolic links were encountered in translat-
                        ing the pathname.

     [ENAMETOOLONG]     A component of a pathname exceeded {NAME_MAX} charac-
                        ters, or an entire path name exceeded {PATH_MAX} char-
                        acters.

     [ENOENT]           The named file does not exist.

     [ENOTDIR]          A component of the path prefix is not a directory.

     [EPERM]            The named file is a directory and the effective user
                        ID of the process is not the super-user, the file sys-
                        tem containing the file does not permit the use of
                        unlink() on a directory, or the directory containing
                        the file is marked sticky, and neither the containing
                        directory nor the file to be removed are owned by the
                        effective user ID.

     [EROFS]            The named file resides on a read-only file system.

     In addition, unlinkat() will fail if:

     [EBADF]            path does not specify an absolute path and fd is nei-
                        ther AT_FDCWD nor a valid file descriptor open for
                        reading or searching.

     [ENOTDIR]          path is not an absolute path and fd is a file descrip-
                        tor associated with a non-directory file; or flag has
                        AT_REMOVEDIR set and path does not name a directory.

     [ENOTEMPTY]        flag has AT_REMOVEDIR set and path is a directory that
                        is not empty.


SEE ALSO

     close(2), link(2), rmdir(2), symlink(7)


STANDARDS

     The unlink() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1'').
     unlinkat() conforms to IEEE Std 1003.1-2008 (``POSIX.1'').


HISTORY

     An unlink() function call appeared in Version 1 AT&T UNIX.

NetBSD 10.1                    September 2, 2019                   NetBSD 10.1