fclose(3)fclose(3)NAME
fclose, fflush, fclose_unlocked, fflush_unlocked - Close or flush a
stream
SYNOPSIS
#include <stdio.h>
int fclose(
FILE *stream ); int fclose_unlocked(
FILE *stream ); int fflush(
FILE *stream ); int fflush_unlocked(
FILE *stream );
LIBRARY
Standard C Library (libc)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
fclose(), fflush(): XSH4.0, XSH4.2, XSH5.0
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Specifies the output or update stream.
DESCRIPTION
The fclose() function writes buffered data to the stream specified by
the stream parameter, and then closes the associated file. The function
is automatically called for all open files when the exit() function is
invoked. Any unwritten buffered data for the stream is delivered to
the host environment to be written to the file; any unread buffered
data is discarded. The stream is disassociated from the file. If the
associated buffer was automatically allocated, it is deallocated. Any
further use of the stream specified by the stream parameter causes
undefined behavior.
The fclose() function performs the close() function on the file
descriptor associated with the stream parameter. If the stream was
writable and buffered data was not yet written to the file, it marks
the st_ctime and st_mtime fields of the underlying file for update.
The fflush() function writes any buffered data for the stream specified
by the stream parameter and leaves the stream open. If stream is a
null pointer, the fflush() function performs this flushing action on
all streams for which the behavior was previously defined. The st_ctime
and st_mtime fields of the underlying file are marked for update.
[Tru64 UNIX] The fclose_unlocked() and fflush_unlocked() functions are
functionally identical to the fclose() and fflush() functions, except
that fclose_unlocked() and fflush_unlocked() may be safely used only
within a scope that is protected by the flockfile() and funlockfile()
functions used as a pair. The caller must ensure that the stream is
locked before these functions are used.
RETURN VALUES
Upon successful completion, the fclose(), fflush(), fclose_unlocked(),
and fflush_unlocked() functions return a value of 0 (zero). Otherwise,
EOF is returned, and errno is set to indicate the error.
ERRORS
The fclose(), fflush(), fclose_unlocked(), and fflush_unlocked() func‐
tions set errno to the specified value for following conditions: The
O_NONBLOCK option is set for the file descriptor underlying the stream
parameter and the process would be delayed in the write operation. The
file descriptor underlying the stream parameter is not valid. An
attempt was made to write a file that exceeds the process's file size
limit or the maximum file size. (See the ulimit(3) reference page).
The file is a regular file and an attempt was made to write at
or beyond the offset maximum associated with the corresponding
stream. The function was interrupted by a signal that was
caught. The TOSTOP tty local mode causes a background process
to get a SIGTTOU signal if it attempts to write to the control‐
ling terminal. The SIGTTOU signal, if it is not caught or
ignored, will cause the process to block in a stopped state. A
process in an orphaned process group is not allowed to become
stopped, since there is no unprivileged process to unblock it.
This condition only applies to operations on stdio streams asso‐
ciated with ttys.
[EIO] is also associated with driver errors. There was no free
space remaining on the device containing the file. An attempt
was made to write to a pipe or FIFO that is not open for reading
by any process. A SIGPIPE signal will also be sent to the
process. A request was made of a nonexistent device or the
request was outside the capabilities of the device.
SEE ALSO
Functions: close(2), exit(2), fopen(3), setbuf(3)
Standards: standards(5)
Network Programmer's Guide
fclose(3)
