关闭一个正在写入stdout的文件

Question

假设我正在把 stdout（标准输出）写入一个文件，像这样：

sys.stdout = open("file.txt", "w")
# print stuff here

这样做是不行的：

sys.stdout.close()

我该怎么做才能在把 stdout 写入文件后关闭这个文件呢？

Answer 1

你可以这样做：

import sys

class writer(object):
    """ Writes to a file """

    def __init__(self, file_name):
        self.output_file = file_name

    def write(self, something):
        with open(self.output_file, "a") as f:
            f.write(something)

if __name__ == "__main__":
    stdout_to_file = writer("out.txt")
    sys.stdout = stdout_to_file
    print "noel rocks"

这个文件只有在你像这样写入内容的时候才会被打开。

Answer 2

如果你想把所有的print()输出都重定向到一个文件里，这也是可以的。这种方法很快，而且在我看来也很有用，但可能会有其他一些影响。如果我说错了，请纠正我。

import sys

stdoutold = sys.stdout
sys.stdout = fd = open('/path/to/file.txt','w')
# From here every print will be redirected to the file
sys.stdout = stdoutold
fd.close()
# From here every print will be redirected to console

Answer 3

我理解你的问题是：“我怎么把 sys.stdout 重定向到一个文件里？”

import sys

# we need this to restore our sys.stdout later on
org_stdout = sys.stdout

# we open a file
f = open("test.txt", "w")
# we redirect standard out to the file
sys.stdout = f
# now everything that would normally go to stdout
# now will be written to "test.txt"
print "Hello world!\n"
# we have no output because our print statement is redirected to "test.txt"!
# now we redirect the original stdout to sys.stdout
# to make our program behave normal again
sys.stdout = org_stdout
# we close the file
f.close()
print "Now this prints to the screen again!"
# output "Now this prints to the screen again!"

# we check our file
with open("test.txt") as f:
    print f.read()
# output: Hello World!

这个回答对你的问题有帮助吗？