The fclose() function causes the stream pointed to by stream to be flushed and the associated file to be closed. Any unwritten buffered data for the stream is 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.

The fclose() function marks for update the st_ctime and st_mtime fields of the underlying file if the stream is writable and if buffered data has not yet been written to the file. It will perform a close(2) operation on the file descriptor that is associated with the stream pointed to by stream.

After the call to fclose(), any use of stream causes undefined behavior.

The fclose() function is performed automatically for all open files upon calling exit(2).

Upon successful completion, fclose() returns 0. Otherwise, it returns EOF and sets errno to indicate the error.

The fclose() function will fail if:

EAGAIN

The O_NONBLOCK flag is set for the file descriptor underlying stream and the process would be delayed in the write operation.

EBADF

The file descriptor underlying stream is not valid.

EFBIG

An attempt was made to write a file that exceeds the maximum file size or the process's file size limit; or the file is a regular file and an attempt was made to write at or beyond the offset maximum associated with the corresponding stream.

EINTR

The fclose() function was interrupted by a signal.

EIO

The process is a member of a background process group attempting to write to its controlling terminal, TOSTOP is set, the process is neither ignoring nor blocking SIGTTOU and the process group of the process is orphaned.

ENOSPC

There was no free space remaining on the device containing the file.

EPIPE

An attempt is 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.

The fclose() function may fail if:

ENXIO

A request was made of a non-existent device, or the request was beyond the limits of the device.

See attributes(5) for descriptions of the following attributes:

close(2), exit(2), getrlimit(2), ulimit(2), fopen(3C), stdio(3C), attributes(5)