NAME
close - delete a descriptor

SYNOPSIS
close(d)
int d;

DESCRIPTION
The close call deletes a descriptor from the per-process object
reference table. If this is the last reference to the underlying
object, then it will be deactivated. For example, on the last
close of a file the current seek pointer associated with the file
is lost; on the last close of a socket(2) associated naming
information and queued data are discarded; on the last close of a
file holding an advisory lock the lock is released (see further
flock(2)).

A close of all of a process’s descriptors is automatic on exit, but
since there is a limit on the number of active descriptors per
process, close is necessary for programs that deal with many
descriptors.

When a process forks (see fork(2)), all descriptors for the new
child process reference the same objects as they did in the parent
before the fork. If a new process is then to be run using
execve(2), the process would normally inherit these descriptors.
Most of the descriptors can be rearranged with dup2(2) or deleted
with close before the execve is attempted, but if some of these
descriptors will still be needed if the execve fails, it is
necessary to arrange for them to be closed if the execve succeeds.
For this reason, the call "fcntl(d, F_SETFD, 1)" is provided,
which arranges that a descriptor will be closed after a successful
execve; the call "fcntl(d, F_SETFD, 0)" restores the default,
which is to not close the descriptor.

RETURN VALUE
Upon successful completion, a value of 0 is returned. Otherwise, a
value of -1 is returned and the global integer variable errno is
set to indicate the error.

ERRORS
Close will fail if:

[EBADF] D is not an active descriptor.

SEE ALSO
accept(2), flock(2), open(2), pipe(2), socket(2), socketpair(2),
execve(2), fcntl(2)