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       unlink, unlinkat - delete a name and possibly the file it refers to


       #include <unistd.h>

       int unlink(const char *pathname);

       #include <fcntl.h>           /* Definition of AT_* constants */
       #include <unistd.h>

       int unlinkat(int dirfd, const char *pathname, int flags);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

           Since glibc 2.10:
               _XOPEN_SOURCE >= 700 || _POSIX_C_SOURCE >= 200809L
           Before glibc 2.10:


       unlink() deletes a name from the filesystem.  If that name was the last link to a file and
       no processes have the file open, the file is deleted and the space it was  using  is  made
       available for reuse.

       If  the  name  was the last link to a file but any processes still have the file open, the
       file will remain in existence until the last file descriptor referring to it is closed.

       If the name referred to a symbolic link, the link is removed.

       If the name referred to a socket, FIFO,  or  device,  the  name  for  it  is  removed  but
       processes which have the object open may continue to use it.

       The unlinkat() system call operates in exactly the same way as either unlink() or rmdir(2)
       (depending on whether or  not  flags  includes  the  AT_REMOVEDIR  flag)  except  for  the
       differences described here.

       If  the  pathname  given  in  pathname is relative, then it is interpreted relative to the
       directory referred to by the file descriptor dirfd (rather than relative  to  the  current
       working  directory  of  the  calling  process,  as  is done by unlink() and rmdir(2) for a
       relative pathname).

       If the pathname given in pathname is relative and dirfd is  the  special  value  AT_FDCWD,
       then  pathname  is  interpreted  relative  to the current working directory of the calling
       process (like unlink() and rmdir(2)).

       If the pathname given in pathname is absolute, then dirfd is ignored.

       flags is a bit mask that can either be specified as 0, or by ORing  together  flag  values
       that control the operation of unlinkat().  Currently only one such flag is defined:

              By  default,  unlinkat()  performs  the equivalent of unlink() on pathname.  If the
              AT_REMOVEDIR flag is  specified,  then  performs  the  equivalent  of  rmdir(2)  on

       See openat(2) for an explanation of the need for unlinkat().


       On success, zero is returned.  On error, -1 is returned, and errno is set appropriately.


       EACCES Write  access to the directory containing pathname is not allowed for the process's
              effective UID, or  one  of  the  directories  in  pathname  did  not  allow  search
              permission.  (See also path_resolution(7).)

       EBUSY  The  file  pathname  cannot  be  unlinked because it is being used by the system or
              another process; for example, it is a  mount  point  or  the  NFS  client  software
              created  it  to  represent  an  active  but  otherwise  nameless  inode ("NFS silly

       EFAULT pathname points outside your accessible address space.

       EIO    An I/O error occurred.

       EISDIR pathname refers to a directory.  (This is the non-POSIX  value  returned  by  Linux
              since 2.1.132.)

       ELOOP  Too many symbolic links were encountered in translating pathname.

              pathname was too long.

       ENOENT A  component in pathname does not exist or is a dangling symbolic link, or pathname
              is empty.

       ENOMEM Insufficient kernel memory was available.

              A component used as a directory in pathname is not, in fact, a directory.

       EPERM  The system does not allow unlinking of directories,  or  unlinking  of  directories
              requires  privileges  that  the  calling  process doesn't have.  (This is the POSIX
              prescribed error return; as noted above, Linux returns EISDIR for this case.)

       EPERM (Linux only)
              The filesystem does not allow unlinking of files.

       EPERM or EACCES
              The directory containing  pathname  has  the  sticky  bit  (S_ISVTX)  set  and  the
              process's  effective  UID  is neither the UID of the file to be deleted nor that of
              the directory containing it, and the process is not  privileged  (Linux:  does  not
              have the CAP_FOWNER capability).

       EROFS  pathname refers to a file on a read-only filesystem.

       The  same  errors that occur for unlink() and rmdir(2) can also occur for unlinkat().  The
       following additional errors can occur for unlinkat():

       EBADF  dirfd is not a valid file descriptor.

       EINVAL An invalid flag value was specified in flags.

       EISDIR pathname refers to a directory, and AT_REMOVEDIR was not specified in flags.

              pathname is relative and dirfd is a file descriptor referring to a file other  than
              a directory.


       unlinkat()  was  added  to  Linux  in kernel 2.6.16; library support was added to glibc in
       version 2.4.


       unlink(): SVr4, 4.3BSD, POSIX.1-2001, POSIX.1-2008.

       unlinkat(): POSIX.1-2008.


   Glibc notes
       On older kernels where unlinkat() is unavailable, the glibc wrapper function falls back to
       the  use of unlink(2) or rmdir(2).  When pathname is a relative pathname, glibc constructs
       a pathname based on the symbolic link in  /proc/self/fd  that  corresponds  to  the  dirfd


       Infelicities  in  the  protocol  underlying  NFS can cause the unexpected disappearance of
       files which are still being used.


       rm(1), chmod(2), link(2), mknod(2), open(2), rename(2),  rmdir(2),  mkfifo(3),  remove(3),
       path_resolution(7), symlink(7)


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