Windows command line pipe command

• SS64
• CMD
• How-to

Some commands, (e.g. COPY) do not place all their error mesages on the error stream, so to capture those you must redirect both STDOUT and
STDERR with command > file 2>&1

Redirection with > or 2> will overwrite any existing file.

You can also redirect to a printer with > PRN or >LPT1 or to the console with >CON

1. What does pipe do in CMD?
2. What is the CMD symbol?
3. What does pipe () return?
4. Does pipe work in Windows?
5. How does pipe work in C?
6. How do I redirect an echo to a file?
7. How do I open a text file in CMD?
8. How do you use % in cmd?
9. What does & mean in cmd?
10. What is a Windows named pipe?
11. What is CS pipe?
12. What is pipe in IPC?
13. How does pipe () work?

What does pipe do in CMD?

What is the CMD symbol?

The most commonly used symbols are the two redirection symbols «>» and «>>» and the so-called pipe, «¦» . (Just to make sure there is no confusion, the «pipe» is the symbol above the back slash on most keyboards.

What does pipe () return?

If pipe is empty and we call read system call then Reads on the pipe will return EOF (return value 0) if no process has the write end open.

Does pipe work in Windows?

What is a Pipe? Like most IPC mechanisms, pipes help facilitate communication between two applications and or processes using shared memory . This shared memory is treated as a file object in the Windows operating system.

How does pipe work in C?

A pipe is a system call that creates a unidirectional communication link between two file descriptors. The pipe system call is called with a pointer to an array of two integers. Upon return, the first element of the array contains the file descriptor that corresponds to the output of the pipe (stuff to be read).

How do I redirect an echo to a file?

$ echo “Hello” > hello. txt The > command redirects the standard output to a file. Here, “Hello” is entered as the standard input, and is then redirected to the file **… $ cat deserts.

How do I open a text file in CMD?

Don’t put quotes around the name of the file that you are trying to open; start «myfile. txt» opens a new command prompt with the title myfile. txt , while start myfile. txt opens myfile.

How do you use % in cmd?

Use a single percent sign ( % ) to carry out the for command at the command prompt. Use double percent signs ( %% ) to carry out the for command within a batch file. Variables are case sensitive, and they must be represented with an alphabetical value such as %a, %b, or %c.

What does & mean in cmd?

The & symbol instructs commands to run in a background process and immediately returns to the command line for additional commands.

What is a Windows named pipe?

A named pipe is a named, one-way or duplex pipe for communication between the pipe server and one or more pipe clients. All instances of a named pipe share the same pipe name, but each instance has its own buffers and handles, and provides a separate conduit for client/server communication.

What is CS pipe?

Carbon steel pipe is used as the base pipe of bimetallic combination tubing, which has an internal liner made of stainless steel, titanium alloy steel, copper or aluminum, and so on.

What is pipe in IPC?

Also see named pipe (or FIFO). In computer programming, especially in UNIX operating systems, a pipe is a technique for passing information from one program process to another. Unlike other forms of interprocess communication (IPC), a pipe is one-way communication only.

How does pipe () work?

pipe() is a system call that facilitates inter-process communication. It opens a pipe, which is an area of main memory that is treated as a «virtual file». The pipe can be used by the creating process, as well as all its child processes, for reading and writing.

Windows 7 / Getting Started

Normally, any output from a console program appears in the Command Prompt window,
but you can redirect it into a file using the > character. For example, the command

tasklist >tasks.txt

generates the same listing as the previous example but stores it in a file named
tasks.txt. Command-line programs send their output to what is called the standard
output stream. By default, anything the program sends to the standard output is printed
in the Command Prompt window. Figure below shows how this looks. The first tasklist command in the figure sends its output to the Command Prompt window.
The second tasklist command has its output redirected into a file.

Some programs read input through a standard input stream. By default, this is connected
to your keyboard, and whatever you type is read by the program. For example,
the sort command reads lines of text from the standard input, sorts them alphabetically,
and writes the results to the standard output. If you type the following lines at the command prompt,

sort
c
b
a
Ctrl+Z

sort spits out the lines in order: a, b, c. (Note that Ctrl+Z on a line by itself indicates
the end of input.) You can redirect the standard input with the < character. For example, the command

sort <somefile.txt

tells sort to read input from the file somefile.txt.You can use both input and output
redirection at the same time.The command

sort <somefile.txt >sortedfile.txt

rearranges the contents of somefile.txt and creates a new file named

sortedfile.txt.

You can also specify that the output isn’t to replace an existing file but rather should
simply be stuck onto the end (that is, appended ) with the characters >>, as in this example:

dir /b c:\ >listing.txt
dir /b d:\ >>listing.txt

The first command creates the file listing.txt, and the second appends its output
onto the end of listing.txt. (If the file listing.txt doesn’t already exist, don’t
worry: >> creates it.)

Finally, you can hook the output of one program directly to the input of another by
using the vertical bar symbol (|), usually found above the backslash (\) on a keyboard.
For example, the find command reads lines from the input and passes only lines containing
a designated string.The command

tasklist | find "winword"

has tasklist send its list of all programs through find which types out only the line
or lines containing «winword.» Finally,

tasklist | find "winword" >tasks.txt

connects tasklist to find, and find to a file.

Input and output redirection let you connect programs and files as if you are making
plumbing connections.The | symbol is often called a pipe for this reason, and programs
such as find are often called filters.

Note One handy filter to know about is more, a program that passes whatever it’s given as input to
its output. What makes more useful is that it pauses after printing a screen full of text. more lets
you view long listings that would otherwise scroll off the screen too quickly to read. For example, the command

tasklist | more

helps you see the entire list of programs. When you see the prompt — More — at the bottom of the
screen, press the spacebar to view the next screen full.

The standard error is another output stream available to console programs. By default, if
a program writes information to the standard error stream, the text appears in the
Command Prompt window. Programs usually use this to display important error messages
that they want you to see, even if the standard output is redirected to a file or
pipe.You can redirect standard error too, though, if you want to capture the error messages in a file.

If you’ve worked with DOS, Linux, or Unix, this is probably already familiar to you.
However, there are several input redirection variations you might not be familiar with.
Table below lists all the redirection instructions that CMD recognizes.

Input and Output Redirection

* The number 1 refers to the standard output stream and the number 2 to the standard error stream.

Two special forms of output redirection are output to the NUL device and output to a
printer.Windows recognizes the special filename nul in any folder on any drive and
treats it as a «black hole» file. If you issue a command and redirect its output to nul,
the output is discarded.This type of direction is useful in batch files when you want a
command to do something, but don’t want or need the user to see any error messages
it might print. For example,

net use f: /del >nul 2>nul

runs the net use command and makes sure that no output appears to the user.

Special filenames LPT1, LPT2, and so on, represent your default printer and your local
printer connected to ports LPT1, LPT2, and so on.You can direct the output of a
command to the printer using redirection to these names.You can also direct output
to network-connected printers by mapping these devices to network printers using
the net use command. Special name PRN is the same as LPT1.

In practical day-to-day use, standard output redirection lets you capture the output
of a console program into a file, where you can edit or incorporate it into your
documents. Standard error redirection is handy when you need to gather hardcopy
evidence from a program that is printing error messages. Input redirection is used most
often in a batch file setting, where you want to have a command run automatically
from input prepared ahead of time.

Here are some examples:

cmd /? | more

This has the CMD command-line shell print its built-in help information, and it
passes the text through more so it can be read a page at a time.

cmd /? > cmd.info
notepad cmd.info

This has CMD print its help information again, but this time, the text is stored in a
file, and you view the file with Notepad. (Window-based programs can be useful on occasion.)

tasklist | sort /+60 | more

This has tasklist list all running programs, and it pipes the listing through sort,
which sorts the lines starting with column 60.This produces a listing ordered by the
amount of memory used by each running program.The sorted output is piped
through more so it can be viewed a page at a time.

date /f >ping.txt
ping www.companyabc.com 2>&1 >>ping.txt

This checks whether the site www.mycompany.com can be reached through the
Internet.The results, including any errors, are stored in a file named ping.txt.You
could then view this file or analyze it with a program.

Most of you are familiar with pipe grep command in Linux. Here I am explaining the equivalent command in Windows command line.

Windows has two different command prompts. One is called the CMD and the other one is PowerShell.

PowerShell is more powerful and user friendly compared to the raw shell in windows. Most of the commands in CMD works in PowerShell, but the commands in PowerShell might not work in CMD.

What is grep command in Linux ?

grep is a command for performing filter and search operation in a file or a folder or in the output of another command.

The syntax of grep command is given below.

grep [options] pattern [files]

Options Description
-c : This prints only a count of the lines that match a pattern
-h : Display the matched lines, but do not display the filenames.
-i : Ignores, case for matching
-l : Displays list of a filenames only.
-n : Display the matched lines and their line numbers.
-v : This prints out all the lines that do not matches the pattern
-e exp : Specifies expression with this option. Can use multiple times.
-f file : Takes patterns from file, one per line.
-E : Treats pattern as an extended regular expression (ERE)
-w : Match whole word
-o : Print only the matched parts of a matching line,
with each such part on a separate output line.

-A n : Prints searched line and n lines after the result.
-B n : Prints searched line and n line before the result.
-C n : Prints searched line and n lines after before the result.

Sample usages are given below.

In the below example, the grep command filters and searches for the string “Flask” in the output of the command pip freeze

pip freeze | grep "Flask"

In the below example, the grep command searches for the string Amal in the file userlist.txt. The option -i performs case insensitive search inside the file.

grep -i "Amal" userlist.txt

grep command equivalent in Windows CMD

findstr is the command equivalent to grep.

Example is given below. In the below examples, the findstr will do an exact match

pip freeze | findstr "Flask"

netstat -an | findstr "80"

To search a string within a file, use findstr in the following way

findstr <search-string> <filename>

Example

findstr Amal userlist.txt

More details of findstr command can be found in this official documentation.

grep command equivalent in Windows PowerShell

findstr command works in powershell. We have another command in powershell which is Select-String

An example usage is given below.

netstat -an | Select-String 80

For searching a string in the contents of a file, use the below syntax

Select-String <string-to-search> <file-name>

Example

Select-String Amal userlist.txt

I hope this explanation is clear. Feel free to comment if you have any questions or suggestions.