Piping on cmd.exe

**bpark** · 11-02-2004

Last year at the Linux show in NYC, I noticed that Microsoft had a nice tool. The guy demonstrated all these things from cmd.exe and one of them was the ability to use the pipe.

Does anyone know what this product is? I know I can install cygwin but I'm curious to know what this product is called.

**jeremy1701** · 11-02-2004

Pipe, in Linux, is the ablity to use the output of one command as the input to another through the use of what's called a pipe. The pipe operator is | (shft + \). As an example, the cat command displays the contents of a file. Lets say file test contains the values 1,2,3,4 on seperate lines.

Code:

cat test

Would output

1
2
3
4

The command grep pattern filename searches for pattern in filename. You can put the two together using a pipe.

Code:

cat test | grep 3

will search the output of cat for the pattern 3. This example may seem lame, but consider searching the contents of /var/log/Xorg.0.log for errors. There may be hundreds of lines in the log. If there was an error, the line starts EE and lists the error.

Code:

cat /var/log/Xorg.0.log | grep EE

Will print only the errors.

Hope that helps,
Jeremy

**lakerdonald** · 11-02-2004

jeremy1701,
i think bpark was asking how to get pipes working on windows.
if that's your question: you can use pipes on cmd.exe without any additional software. piping and subdirectories were two things that ms-dos "borrowed" from UNIX.
-lakerdonald

**bpark** · 11-02-2004

Ahh, I see.

I forgot that cmd.exe has redirection including the functionality of piping.

I guess the only thing then would be to install cygwin and edit the path env for those additional programs.

**lakerdonald** · 11-02-2004

wait what? why would you need to edit stuff? piping is part of the DOS shell to the core

**scientica** · 11-02-2004

let me thingk, the so called pipe line rediercting ad modum BigCorp is eitehr terrible broken or just a bad implementation... iirc, winDOS only supports (parts of) the most rudamentary redirection:
'>', '>>' and '|' ('2>' or something like that *should* work, but I nerver got it to work in windos... )

**lakerdonald** · 11-02-2004

i never got what 2> did...

**lordnothing** · 11-02-2004

it redirects a file descriptor...

**monkey8** · 11-02-2004

Originally Posted by lakerdonald

i never got what 2> did...

Code:

$ man bash

0 - standard input
1 - standard output
2 - standard error output

**bpark** · 11-02-2004

Lakedonald:

After installing Cygwin, the PATH env variable in Windows needs to be edited to add the directory path to the newly installed Cygwin programs.

Piping is built into the shell. There's nothing you need to edit for this part.

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