Python：-u选项的意义？

来自

python --help

-u     : unbuffered binary stdout and stderr; also PYTHonUNBUFFERED=x         see man page for details on internal buffering relating to '-u'

手册页指出：

-u     Force  stdin,  stdout and stderr to be totally unbuffered.  On

systems where it matters, also put stdin,
stdout and stderr in binary mode. Note that there is internal
buffering in xreadlines(), readlines()
and file-object iterators (“for line in sys.stdin”) which is
not influenced by this option. To work
around this, you will want to use “sys.stdin.readline()” inside a
“while 1:” loop.

Python以缓冲模式打开stdin，-out和-error流；它会读取或写入更大的块，将数据保留在内存中，直到达到阈值为止。

-u

此外，python可以解释打开文件上的换行符，并将它们与本机平台换行符进行相互转换（文本模式）。该

-u

rn

rb

wb

open()