unlink — remove directory entry; delete file
int unlink(const char *path);
system call removes the directory entry named by the path name pointed to by
When all links to a file have been removed
and no process has the file open,
the space occupied by the file is freed and the file ceases to exist.
If one or more processes have the file open
when the last link is removed,
only the directory entry is removed immediately
so that processes that do not already have the file open
cannot access the file.
After all processes close their references to the file,
if there are no more links to the file,
the space occupied by the file is then freed
and the file ceases to exist.
returns the following values:
is set to indicate the error.
is set to one of the following values:
Search permission is denied for a component of the path prefix.
Write permission is denied on the directory containing the link to be removed.
The process does not have read/write access permission to the parent
The entry to be unlinked is the mount point for a mounted file system.
points outside the process's allocated address space.
The reliable detection of this error is implementation dependent.
Too many symbolic links were encountered in translating the path name.
The length of the specified path name exceeds
bytes, or the length of a component of the path name exceeds
is in effect.
The named file does not exist (for example,
is null or a component of
does not exist).
A component of the path prefix is not a directory.
The directory containing the file to be removed
has the sticky bit set and neither the containing directory
nor the file to be removed are owned by the effective user
The named file is a directory and
the effective user
is not a user with appropriate privileges. Some file systems return
this error whenever the named file is a directory, regardless of the
The directory entry to be unlinked is part of a read-only file system.
The entry to be unlinked is the last link to a pure procedure
(shared text) file that is being executed.
is used on a directory that is
empty (contains files other than
the directory is unlinked, the files become orphans,
and the directory link count is left with an inaccurate value
unless they are linked by some other directory.
is used on a directory that
empty (contains only the files
the directory is unlinked,
but the parent directory's link count is left with an inaccurate value.
In either of the above cases, the file system should be checked using
To avoid these types of problems, use
unlink(): AES, SVID2, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1