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Manual Pages for UNIX Operating System command usage for man unlinkat

System Calls unlink(2)

NAME

unlink, unlinkat - remove directory entry

SYNOPSIS

#include

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 unlin-

kat() 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 , unlinkat() also behaves the same as unlink().

Otherwise, path is resolved relative to the directory refer-

enced by the dirfd argument.

If the flag argument is set to the value AT_REMOVEDIR,

defined in , unlinkat() behaves the same as

rmdir(2) except in the processing 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 refer-

ences to the file are closed.

If the path argument is a directory and the filesystem sup-

ports 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

SunOS 5.11 Last change: 18 May 2007 1

System Calls unlink(2) 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 exam-

ple, 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 charac-

ters and the file system accepts only file names where all characters are part of the

UTF-8 character codeset.

SunOS 5.11 Last change: 18 May 2007 2

System Calls unlink(2) 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 descrip-

tor 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 pro-

duced an intermediate result whose length

exceeds {PATH_MAX}.

ETXTBSY The entry to be unlinked is the last direc-

tory entry to a pure procedure (shared text) file that is being executed.

SunOS 5.11 Last change: 18 May 2007 3

System Calls unlink(2)

USAGE

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

ATTRIBUTES

See attributes(5) for descriptions of the following attri-

butes:

____________________________________________________________

| ATTRIBUTE TYPE | ATTRIBUTE VALUE |

|_____________________________|_____________________________|

| Interface Stability | Committed |

|_____________________________|_____________________________|

| 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 Last change: 18 May 2007 4




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