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CLOSE(2) UNIX Programmer's Manual CLOSE(2)
NNAAMMEE
cclloossee - delete a descriptor
SSYYNNOOPPSSIISS
##iinncclluuddee <<uunniissttdd..hh>>
_i_n_t
cclloossee(_i_n_t _d)
DDEESSCCRRIIPPTTIIOONN
The cclloossee() call deletes a descriptor from the perprocess object refer
ence table. If this is the last reference to the underlying object, the
object will be deactivated. For example, on the last close of a file the
current _s_e_e_k pointer associated with the file is lost; on the last close
of a socket(2) associated naming information and queued data are discard
ed; on the last close of a file holding an advisory lock the lock is re
leased (see further flock(2)).
When a process exits, all associated file descriptors are freed, but
since there is a limit on active descriptors per processes, the cclloossee()
function call is useful when a large quanitity of file descriptors are
being handled.
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 cclloossee() before the execve is at
tempted, but if some of these descriptors will still be needed if the ex
ecve fails, it is necessary to arrange for them to be closed if the ex
ecve succeeds. For this reason, the call ``fcntl(d, F_SETFD, 1)'' is
provided, which arranges that a descriptor will be closed after a suc
cessful execve; the call ``fcntl(d, F_SETFD, 0)'' restores the default,
which is to not close the descriptor.
RREETTUURRNN VVAALLUUEESS
Upon successful completion, a value of 0 is returned. Otherwise, a value
of 1 is returned and the global integer variable _e_r_r_n_o is set to indi
cate the error.
EERRRROORRSS
CClloossee() will fail if:
[EBADF] _D is not an active descriptor.
[EINTR] An interupt was received.
SSEEEE AALLSSOO
accept(2), flock(2), open(2), pipe(2), socket(2), socketpair(2),
execve(2), fcntl(2)
SSTTAANNDDAARRDDSS
CClloossee() conforms to IEEE Std 1003.11988 (``POSIX'').
4th Berkeley Distribution March 10, 1991 1