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UNLINK(2)                  Linux Programmer's ManualUNLINK(2)NAME       unlink, unlinkat - delete a name and possibly the file it refers toSYNOPSIS       #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 (seefeature_test_macros(7)):       unlinkat():           Since glibc 2.10:               _POSIX_C_SOURCE >= 200809L           Before glibc 2.10:               _ATFILE_SOURCEDESCRIPTION       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.   unlinkat()       The  unlinkat()  system call operates in exactly the same way as either       unlink() orrmdir(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() andrmdir(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() andrmdir(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  to-       gether  flag  values  that  control  the operation of unlinkat().  Cur-       rently, only one such flag is defined:       AT_REMOVEDIR              By default, unlinkat() performs the equivalent  of  unlink()  on              pathname.   If the AT_REMOVEDIR flag is specified, then performs              the equivalent ofrmdir(2) on pathname.       Seeopenat(2) for an explanation of the need for unlinkat().RETURN VALUE       On success, zero is returned.  On error, -1 is returned, and  errno  is       set appropriately.ERRORS       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_reso-lution(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 renamed").       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  path-              name.       ENAMETOOLONG              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.       ENOTDIR              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).       EPERM  The file to be unlinked  is  marked  immutable  or  append-only.              (Seeioctl_iflags(2).)       EROFS  pathname refers to a file on a read-only filesystem.       The same errors that occur for unlink() andrmdir(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  speci-              fied in flags.       ENOTDIR              pathname is relative and dirfd is a file descriptor referring to              a file other than a directory.VERSIONS       unlinkat() was added to Linux in kernel  2.6.16;  library  support  was       added to glibc in version 2.4.CONFORMING TO       unlink(): SVr4, 4.3BSD, POSIX.1-2001, POSIX.1-2008.       unlinkat(): POSIX.1-2008.NOTES   Glibc notes       On  older  kernels  where  unlinkat() is unavailable, the glibc wrapper       function falls back to the use of unlink() orrmdir(2).  When  pathname       is  a  relative pathname, glibc constructs a pathname based on the sym-       bolic link in /proc/self/fd that corresponds to the dirfd argument.BUGS       Infelicities in the protocol underlying NFS can  cause  the  unexpected       disappearance of files which are still being used.SEE ALSOrm(1),unlink(1),chmod(2),link(2),mknod(2),open(2),rename(2),rmdir(2),mkfifo(3),remove(3),path_resolution(7),symlink(7)COLOPHON       This page is part of release 5.05 of the Linux  man-pages  project.   A       description  of  the project, information about reporting bugs, and the       latest    version    of    this    page,    can     be     found     at       https://www.kernel.org/doc/man-pages/.Linux                             2017-09-15UNLINK(2)