CLOSE(2)CLOSE(2)NAMEclose - delete a descriptor
SYNOPSIS
#include <unistd.h>
int close(int d)
DESCRIPTION
The close call deletes a descriptor from the per-process object refer‐
ence 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 TCP/IP descriptor 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 fcntl(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,
flags)'' is provided, that can be used to mark a descriptor "close on
exec" by setting the FD_CLOEXEC flag:
fcntl(d, F_SETFD, fcntl(d, F_GETFD) | FD_CLOEXEC);
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 ALSOopen(2), pipe(2), execve(2), fcntl(2).
4th Berkeley Distribution May 22, 1986 CLOSE(2)
