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中国DOS联盟论坛 » DOS批处理 & 脚本技术（批处理室） » What does 2>nul 1>nul in batch processing statements mean?
DigestI
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DigestI
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Floor 31
Posted 2007-03-18 03:35 · 中国 浙江 温州 电信
Floor 32
Posted 2007-05-29 17:28 · 中国 北京 海淀区 IDC机房
The following is the analysis:
First, "set mhnet=%temp%\mhnet" means to set the variable "mhnet" to the path which is the "temp" folder (a system temporary folder) combined with the subfolder name "mhnet".
Then, "rmdir /S /Q %mhnet% 2>NUL 1>NUL" is to delete the folder and its sub - folders (/S means delete sub - folders recursively, /Q means quiet mode) and redirect the error and output information to null.
Finally, "mkdir %mhnet%" is to create the folder specified by the "mhnet" variable.
So, %mhnet% is a folder path which is the "temp" folder's sub - folder named "mhnet".
First, "set mhnet=%temp%\mhnet" means to set the variable "mhnet" to the path which is the "temp" folder (a system temporary folder) combined with the subfolder name "mhnet".
Then, "rmdir /S /Q %mhnet% 2>NUL 1>NUL" is to delete the folder and its sub - folders (/S means delete sub - folders recursively, /Q means quiet mode) and redirect the error and output information to null.
Finally, "mkdir %mhnet%" is to create the folder specified by the "mhnet" variable.
So, %mhnet% is a folder path which is the "temp" folder's sub - folder named "mhnet".
Floor 33
Posted 2007-08-31 17:02 · 中国 江苏 苏州 联通
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Went shopping all day, got quite a haul. :lol:
Floor 34
Posted 2007-09-17 11:34 · 中国 广东 广州 增城区 电信
It's too profound. When will I be able to understand it?
Floor 35
Posted 2007-09-18 21:23 · 中国 上海 浦东新区 电信
Leave a footprint, digest it slowly in the future~~
Floor 36
Posted 2007-09-19 20:35 · 中国 四川 德阳 电信
Awesome
Floor 37
Posted 2007-09-21 19:03 · 中国 北京 雅虎中国
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The null device NUL is a special device because it has no controllable PC hardware or ports, but is just a fictional device or port that only exists at the software level. Because of this, it can accept all redirected input and output requests without giving any response. Under NT, it will end the input request without giving any input information. Under DOS, it repeatedly fills 127 binary bytes of 1 (displayed as ^A) and then terminates the response. This characteristic makes it very similar to the "black hole" in astronomy that can devour all matter and information, and also very similar to the "mysterious way" in philosophy that can reverse yin and yang and create from nothing. The reason for its existence is that we need a "recycling bin" that can silently and unconditionally absorb various redundant output information or input requests, just as the "black hole" is like a huge "cosmic garbage dump".
Precise!......
★①②③④⑤⑥⑦⑧⑨⑩㈠㈡㈢㈣㈤㈥㈦㈧㈨㈩ⅠⅡⅢⅣⅤⅥⅦⅧⅨⅩⅪⅫ【●】→←↑↓▲
Floor 38
Posted 2007-10-05 10:33 · 中国 浙江 宁波 电信
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Nice
Floor 39
Posted 2007-10-09 19:23 · 中国 福建 厦门 电信
Bump
Floor 40
Posted 2007-10-11 01:34 · 中国 广东 惠州 电信
Very readable~!
Floor 41
Posted 2007-10-15 17:55 · 中国 北京 石景山区 联通
I have always seen such things, and I saw this time
Floor 42
Posted 2007-10-16 18:30 · 中国 广东 东莞 电信
A bit too deep, hard to understand.
Floor 43
Posted 2008-01-22 13:15
Nice
Floor 44
Posted 2008-01-30 17:58 · 中国 香港 新世界电讯
Great! Save it for later to savor slowly.
Floor 45
Posted 2008-01-31 02:18 · 中国 贵州 贵阳 电信
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Is there a difference between NUL and NULL? If there is, what is the difference?
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