unlink(2)							   System Calls 							 unlink(2)

NAME

       unlink, unlinkat - remove directory entry

SYNOPSIS

       #include <unistd.h>

       int unlink(const char *path);

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

DESCRIPTION

       The  unlink()  function	removes a link to a file. If path names a symbolic link, unlink() removes the symbolic link named by path and does
       not affect any file or directory named by the contents of the symbolic link.  Otherwise, unlink() removes the link named  by  the  pathname
       pointed to by path and decrements the link count of the file referenced by the link.

       The  unlinkat() function also removes a link to a file. See fsattr(5). If the flag argument is 0, the behavior of unlinkat() is the same as
       unlink() except in the processing of its path argument. If path is absolute, unlinkat() behaves the same as unlink() and the dirfd argument
       is unused. If path is relative and dirfd has the value AT_FDCWD, defined in <fcntl.h>, unlinkat() also behaves the same as unlink(). Other-
       wise, path is resolved relative to the directory referenced by the dirfd argument.

       If the flag argument is set to the value AT_REMOVEDIR, defined in <fcntl.h>, unlinkat() behaves the same as rmdir(2) except in the process-
       ing of the path argument as described above.

       When  the  file's  link	count  becomes 0 and no process has the file open, the space occupied by the file will be freed and the file is no
       longer accessible. If one or more processes have the file open when the last link is removed,  the  link  is  removed  before  unlink()	or
       unlinkat() returns, but the removal of the file contents is postponed until all references to the file are closed.

       If  the path argument is a directory and the filesystem supports unlink() and unlinkat() on directories, the directory is unlinked from its
       parent with no cleanup being performed.	In UFS, the disconnected directory will be found the next time	the  filesystem  is  checked  with
       fsck(1M). The unlink() and unlinkat() functions will not fail simply because a directory is not empty. The user with appropriate privileges
       can orphan a non-empty directory without generating an error message.

       If the path argument is a directory and the filesystem does not support unlink() and unlink() on directories (for example, ZFS),  the  call
       will fail with errno set to EPERM.

       Upon  successful completion, unlink() and unlinkat() will mark for update the st_ctime and st_mtime fields of the parent directory.  If the
       file's link count is not 0, the st_ctime field of the file will be marked for update.

RETURN VALUES

       Upon successful completion, 0 is returned.  Otherwise, -1 is returned, errno is set to indicate the error, and the file is not unlinked.

ERRORS

       The unlink() and unlinkat() functions will fail if:

       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.

       EACCES	       The  parent  directory  has  the  sticky bit set and the file is not writable by the user, the user does not own the parent
		       directory, the user does not own the file, and the user is not a privileged user.

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

       EFAULT	       The path argument points to an illegal address.

       EILSEQ	       The path argument includes non-UTF8 characters and the file system accepts only file names where all characters are part of
		       the UTF-8 character codeset.

       EINTR	       A signal was caught during the execution of the unlink() function.

       ELOOP	       Too many symbolic links were encountered in translating path.

       ENAMETOOLONG    The  length of the path argument exceeds PATH_MAX, or the length of a path component exceeds NAME_MAX while _POSIX_NO_TRUNC
		       is in effect.

       ENOENT	       The named file does not exist or is a null pathname.

       ENOLINK	       The path argument points to a remote machine and the link to that machine is no longer active.

       ENOTDIR	       A component of the path prefix is not a directory or the provided directory descriptor for unlinkat() is  not  AT_FDCWD	or
		       does not reference a directory.

       EPERM	       The  named  file  is a directory and {PRIV_SYS_LINKDIR} is not asserted in the effective set of the calling process, or the
		       filesystem implementation does not support unlink() or unlinkat() on directories.

       EROFS	       The directory entry to be unlinked is part of a read-only file system.

       The unlink() and unlinkat() functions may fail if:

       ENAMETOOLONG    Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}.

       ETXTBSY	       The entry to be unlinked is the last directory entry to a pure procedure (shared text) file that is being executed.

USAGE

       Applications should use rmdir(2) to remove a directory.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |unlink()	  is	Standard;  |
       |			     |unlinkat() is Evolving	   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |Async-Signal-Safe 	   |
       +-----------------------------+-----------------------------+

SEE ALSO

       rm(1), close(2), link(2), open(2), rmdir(2), remove(3C), attributes(5), privileges(5), fsattr(5)

SunOS 5.11							    18 May 2007 							 unlink(2)