尝试使命令静音时，Dos2unix无法正常工作 [英] Dos2unix not working when trying to silence command

问题描述

我是这样从Python内部调用dos2unix的:

I was calling dos2unix from within Python this way:

call("dos2unix " + file1, shell=True, stdout=PIPE)

无论如何，我都是这样做的:

However to silence the Unix output, I did this:

f_null = open(os.devnull, 'w')
call("dos2unix " + file1, shell=True, stdout=f_null , stderr=subprocess.STDOUT)

这似乎不起作用.该命令不再被调用，因为我在file1与file2上执行的差异(没有diff -y file1 file2 | cat -t并且可以看到行尾未更改).

This doesn't seem to work. The command isn't being called anymore as the diff that I perform on the file1 against file2 (did a diff -y file1 file2 | cat -t and could see the line endings hadn't changed).

file2是我正在比较file1的文件.它具有在包装盒上生成的Unix行尾.但是，file1可能没有.

file2 is the file I am comparing file1 against. It has Unix line endings as it is generated on the box. However, there is a chance that file1 doesn't.

推荐答案

不确定，为什么，但是我会尝试消除您命令&周围的噪音"检查返回码:

Not sure, why but I would try to get rid of the "noise" around your command & check return code:

check_call(["dos2unix",file1], stdout=f_null , stderr=subprocess.STDOUT)

• 作为args列表而不是命令行传递(支持其中包含空格的文件！)
• 删除shell=True，因为dos2unix不是内置的shell命令
• 使用check_call，因此引发异常，而不是无声地失败
• pass as list of args, not command line (support for files with spaces in it!)
• remove shell=True as dos2unix isn't a built-in shell command
• use check_call so it raises an exception instead of failing silently

无论如何，dos2unix可能检测到输出不再是tty，并决定转储输出(dos2unix可以从标准输入&至标准输出工作).我会解释一下.您可以通过重定向到 real 文件而不是os.devnull来检查它，并检查结果是否在那里.

At any rate, it is possible that dos2unix detects that the output isn't a tty anymore and decides to dump the output in it instead (dos2unix can work from standard input & to standard output). I'd go with that explanation. You could check it by redirecting to a real file instead of os.devnull and check if the result is there.

但是我会改做一个纯python解决方案(为了安全起见带有备份)，该解决方案可移植并且不需要dos2unix命令(因此它也适用于Windows):

But I would do a pure python solution instead (with a backup for safety), which is portable and doesn't need dos2unix command (so it works on Windows as well):

with open(file1,"rb") as f:
   contents = f.read().replace(b"\r\n",b"\n")
with open(file1+".bak","wb") as f:
   f.write(contents)
os.remove(file1)
os.rename(file1+".bak",file1)

完全读取文件速度很快，但可能会阻塞非常大的文件.逐行解决方案也是可行的(仍然使用二进制模式):

reading the file fully is fast, but could choke on really big files. A line-by-line solution is also possible (still using the binary mode):

with open(file1,"rb") as fr, open(file1+".bak","wb") as fw:
   for l in fr:
      fw.write(l.replace(b"\r\n",b"\n"))
os.remove(file1)
os.rename(file1+".bak",file1)

这篇关于尝试使命令静音时，Dos2unix无法正常工作的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！