CLOSE(2) Linux Programmer's Manual CLOSE(2)
NAME
close - close a file descriptor
//关闭一个fd
SYNOPSIS
#include <unistd.h>
int close(int fd);
DESCRIPTION
close() closes a file descriptor, so that it no longer refers to any file and
may be reused. Any record locks (see fcntl(2)) held on the file it was
associated with, and owned by the process, are removed (regardless of the file
descriptor that was used to obtain the lock).
//close()关闭一个fd,这样fd就不会被其他文件调用和再次使用.任何对文件抓紧不放的记录锁是有联系的,
//被进程所有的,被清除(除了fd被使用来阻止这个锁).??
If fd is the last file descriptor referring to the underlying open file
description (see open(2)), the resources associated with the open file
description are freed; if the descriptor was the last reference to a file
which has been removed using unlink(2) the file is deleted.
//如果fd是使用open()打开的最后文件的fd,与打开文件联系的资源就被释放.
//如果fd是使用unlink()打开的最后文件的fd,那么文件被删除
RETURN VALUE
close() returns zero on success. On error, -1 is returned, and errno is set
appropriately.
//成功:0
//错误:-1
ERRORS
EBADF fd isn't a valid open file descriptor.
//fd不是一个有效的打开的fd
EINTR The close() call was interrupted by a signal; see signal(7).
//close()被信号中断
EIO An I/O error occurred.
//发生I/O错误
CONFORMING TO
SVr4, 4.3BSD, POSIX.1-2001.
NOTES
Not checking the return value of close() is a common but nevertheless serious
programming error. It is quite possible that errors on a previous write(2)
operation are first reported at the final close(). Not checking the return
value when closing the file may lead to silent loss of data. This can
especially be observed with NFS and with disk quota.
//一般是不检查close()的返回值的,但是仍然会有一些程序错误.很可能在之前的write()操作在最后的
//close()时被报告出来.当关闭文件会导致数据的静静的流失的时候,不要渐染返回值.
A successful close does not guarantee that the data has been successfully
saved to disk, as the kernel defers writes. It is not common for a file
system to flush the buffers when the stream is closed. If you need to be sure
that the data is physically stored use fsync(2). (It will depend on the disk
hardware at this point.)
//成功的关闭并不能保证数据成功的写入磁盘,因为kernel会延迟写入.当流关闭的时候文件系统冲洗缓存
//不是一个普遍的现象.如果你需要确认数据被物理的存储你可以使用fsync().(这取决于在此点是的硬盘)
It is probably unwise to close file descriptors while they may be in use by
system calls in other threads in the same process. Since a file descriptor
may be reused, there are some obscure race conditions that may cause
unintended side effects.
//当在同一进程的不同线程中系统调用fd的时候就关闭fd可能是不明智的.因为fd可以被再使用,
//有一些模糊的竞态条件可能会导致无意识的作用.
SEE ALSO
fcntl(2), fsync(2), open(2), shutdown(2), unlink(2), fclose(3)
COLOPHON
This page is part of release 3.29 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
Linux 2007-12-28 CLOSE(2)
