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The time now is 2026-08-12 17:33

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DOS学习入门 & 精彩文章（教学室） » Who knows the usage of the redirection commands < and << in Dos?

Floor1　qingteng1983	Posted 2006-11-24 09:51
新手上路　Posts 2　Credits 6
Although the materials all say that it can read things from files, there are no examples. Now I have a text file with only one number. I want to read it out and assign it to a variable. How to do it? I tried set var=<a.txt, which doesn't work. Hope to get some ideas or materials!

Floor2　bailang3106	Posted 2008-09-19 14:17
初级用户　Posts 19　Credits 36
Help to top up. I also want to know how to do it. Most of the things in the forum are >.

Floor3　wwmmc	Posted 2008-11-27 16:15
初级用户　Posts 62　Credits 35
">" and ">>" are both output redirections. However, ">>" appends the content to be output to the end of the document. For example: @echo off dir > d:\1.txt pause @echo off dir >> d:\1.txt pause You can see the difference by having a look.

Floor4　HAT	Posted 2008-11-27 17:22
版主　Posts 5,017　Credits 9,023
It is suggested to ask questions in the Batch Processing Room

Floor5　DOSforever	Posted 2008-11-27 19:59
金牌会员　Posts 2,239　Credits 4,639
Hehe, I don't think this is only related to batch processing. Redirecting command lines can also be used.

Floor6　alchemist	Posted 2008-11-28 21:39
高级用户　Posts 193　Credits 652
< is input redirection, providing the internal response of the software. The content of dir.txt has only one byte which is D. For example, xcopy adir bdir < dir.txt. When prompted "Does 2 specify a file name or directory name on the target (F = File, D = directory)", the answer "D" will automatically become the answer and the copy continues.

Floor7　alchemist	Posted 2008-11-28 21:43
高级用户　Posts 193　Credits 652
Originally posted by wwmmc at 2008-11-27 16:15: ">" ">>" Both are output redirections However, ">>" appends the content to be output to the end of the document For example: @echo off dir > d:\1.txt pause @echo off ... There are several other uses for the output redirection ">", such as dir > PRN This sends the content output by dir directly to the printer (only printers using the LPT port) And the following pkunzip aa.zip c:\tools > nul This means no decompression information is output during the decompression of aa.zip

Floor9　earth123xinyuan	Posted 2009-02-10 13:45
社区乞丐　Posts 25　Credits -46　From 内蒙
Hope there are some experts to give a few examples

Floor10　pujihong123	Posted 2009-02-12 22:35
初级用户　Posts 27　Credits 47　From 甘肃. 武威
Take it back and Google it a bit!