Windows Piping to a file from CMD - windows

Quick question that I couldn't find an answer to. When piping to a file as such:
echo "hello" > hello.txt
does this operation actually call notepad.exe on Windows, or is this a non application level file operation?

No, echo is a builtin command in the windows Command Prompt (cmd.exe) used to display/output messages.
The output redirector, >, followed by a file path makes cmd.exe write the message to that file instead of to your screen.
You can see the full list of builtin commands in cmd.exe by typing help at the command prompt

echo is an internal command, which means it is built in to the windows command shell cmd.exe.
Source Internal commands:
The Windows CMD shell CMD.exe contains a number of 'internal' commands.
...
ASSOC, BREAK, CALL ,CD/CHDIR, CLS, COLOR, COPY, DATE, DEL, DIR, DPATH,
ECHO, ENDLOCAL, ERASE, EXIT, FOR, FTYPE, GOTO, IF, KEYS, MD/MKDIR,
MKLINK (vista and above), MOVE, PATH, PAUSE, POPD, PROMPT, PUSHD, REM,
REN/RENAME, RD/RMDIR, SET, SETLOCAL, SHIFT, START, TIME, TITLE, TYPE,
VER, VERIFY, VOL
Piping (a form of redirection) is also performed by the windows command shell cmd.exe.
See Redirection for more information.
The means that when you execute echo "hello" > hello.txt the whole of the command (the echo followed by the redirection is performed by cmd.exe.

Related

cmd redirection: equivalent of bash exec >file

In bash, with
exec >file
all output from stdout will be redirected.
Is there an equivalence in windows cmd.exe?
== P.S. ==
Why need it?
In our application, which needed to support embedded shell(cmd.exe on windows), to achieve better text search support, we decided to decouple command execution from output display.
Under bash, we have used exec >file to achieve that, which works seamlessly. But my cmd expertise is insufficient to find an equivalent command under windows.
== EDIT ==
to clarify what exec >file do in bash
after exec >file in bash, file descriptor 1, i.e., its stdout being redirected to file. which is different from mycommand >file.
In former case, stdout of shell itself being redirected, stdout of any command running inside it has not being technically redirected, but since it's child process of shell, the stdout is inherited, thus run ls after exec >file, ls's output will write to `file.
In latter case, stdout of shell itself has unchanged, only child process's stdout being redirected (by shell, its parent process).
In summary, what I ask is how to redirect cmd.exe itself's stdout, then use cmd.exe interactively just as normal, except cmd.exe don't write anything to console, all output write to file.
Thus, below approaches is not what i pursuit
dir >file
wrap_several_command_to_batch_file >file
wrap_several_command_to_batch_file_and_redirect_inside_then_exit
There is no equivalent to the exec command.
But it can be emulated by restarting the own batch file.
This works only for all commands in the batch file itself, but ends when the batch ends.
#echo off
REM *** Trampoline jump for function calls of the form ex. "C:\:function:\..\ownBatchFile.bat"
FOR /F "tokens=3 delims=:" %%L in ("%~0") DO goto :%%L
REM *** Emulated exec
REM *** Restart this batch file with the function name inside %0
REM *** Parameters are appended, but works only for simple parameters
call "%~d0\:exec:\..\%~pnx0" %* > file
exit /b
:exec
echo This will be redirected
If you want to redirect also from the command line, there are two different possibilities.
Start cmd with a redirection.
cmd /k > file
Disturb the file handles, by redirection restore failures.
The redirection works, but can't be restored later (only by exit the cmd instance).
Read more at More fun with redirection and file handles
echo dummy >NUL 2> nul 3> file
The second example works, because when there are multiple redirections at a time, then the restoring of the file handles fails, because the order of restoring is done in the wrong order by cmd.exe.

Clear PowerShell console in bash on Windows

I download bash.exe from SourceForge and added it to my path in Powershell, but I can't get it to clear the console. clear.exe is missing from the zipfile that was downloaded, so it makes sense that that command doesn't work. However, using Ctrl+L also does not clear the powershell console.
How can I get the powershell console to clear when I'm using bash in it?
Note: I've tried adding an alias called clear to my .bashrc as alias clear=echo <many enters>, but it doesn't work quite the way I've expected (i.e. only echoes 4 or 5 newlines). Also, echo "\n\n" just prints out literal \n\n.
In the absence of a clear or tput utility, and given that the usual ANSI escape sequences don't work with the (built-in) printf, you must call out to either cmd.exe or PowerShell to effect clearing the screen:
bash$ powershell -noprofile -c cls
Using cmd is faster, but the problem is that the win-bash invokes external programs by double-quoting each argument behind the scenes, which causes a command such as cmd /c cls to malfunction; the following workaround mostly works, but prints the cmd.exe prompt string once after clearing the screen.
# !! Clears the screen, but prints the cmd.exe prompt string once.
bash$ echo cls | cmd

Bash in Git for Windows: Weirdness when running a command with CMD.exe /C with args

This is more of an annoyance rather than a problem but I would very much like to understand the semantics here.
All I want to do is to run an arbitrary command on a temporary command-prompt session which itself running under a bash session.
My success rate is 50/50 as some command works as expected whereas others not so much.
I think the problem may lie around arguments not lining up properly (i.e. missing or merged arguments)
I'll try to explain what I mean by weird by a series of commands and responses. (I'm trying to get the word test to be printed on the screen.)
I'm running these under GNU bash, version 3.1.0(1)-release (i686-pc-msys) Bundled with Git-1.8.4:
First attempt:
$ cmd /c echo test
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.
c:\>
Second attempt:
$ cmd '/c echo test'
test"
Third attempt:
$ cmd "/c echo test"
test"
Fourth attempt:
$ cmd /c\ echo\ test
test"
Fifth attempt:
$ cmd "/c echo" test
'echo" test' is not recognized as an internal or external command,
operable program or batch file.
I'd really appreciate any pointers or insights into the behaviors above as this is unintuitional to me and driving me crazy!
Edit:
There is another question that appears similar to this, but it really isn't, mainly because it's about running batch files through CMD /C that doesn't require any arguments.
It doesn't really answer my question about how to provide arguments properly to windows command line apps, and even though the examples are about CMD /C, the answer here can be applied to many other Windows command line apps as well.
This is actually documented in the ReleaseNotes file (in the top level folder of your installed Git for Windows)
Also, extra care has to be paid to pass Windows programs Windows paths, as they have no clue about MSys style POSIX paths -- You can use something like $(cmd //c echo "$POSIXPATH").
If you use cmd //c echo test it works as expected.
$ cmd //c echo test
test
The cause is to do with trying to ensure that posix paths end up being passed to the git utilities properly. For this reason, Git for Windows includes a modified MSYS layer that affects command arguments. You should note that it is not intended that the bash shell and tools provided with Git for Windows be used as general purpose unix tools for Windows. If you want a general purpose unix-style toolset then you should install MSYS or cygwin. The Git Bash shell is setup for working with git and sometimes that shows.
After reading this article I've found solution which works for me:
$ cat gvim.sh
cmd << EOD
gvim $#
EOD
$
Windows 8.1, Git (version 1.9.5-preview20141217), GNU bash, version 3.1.20(4)-release (i686-pc-msys).
I am able to mostly reproduce the problem using gnu bash for Windows.
I can't quite establish a pattern with the first form without any quotes. It seems to work with the Windows ECHO command, but not with other commands like DIR. EDIT - It turns out gnu bash is putting quotes around my command, so echo test becomes "echo" "test". The quotes cause cmd.exe to look for an external command instead of the internal ECHO command. I happen to have "echo.exe", so it appears to run. The odd thing is the quotes around test are not displayed. When I attempt to run the DIR command, it fails entirely because there isn't any DIR.EXE.
The subsequent forms with quotes (except the last one), or escaped spaces, work the same as you are seeing - there is an unwanted trailing quote in the command.
I could not come up with a clean solution. However, I have an ugly hack that should give you the desired result. Simply concatenate a REM command at the end of your command. The REM will comment out the unwanted trailing quote. It is important that there be a space after REM, otherwise REM" will not be recognized as a valid command. Any of the following should work.
$ cmd '/c echo test&rem '
$ cmd "/c echo test&rem "
$ cmd /c\ echo\ test\&rem\
Note that the last command has a space after the backslash.
The technique should work for pretty much any command string that you might want to execute via CMD.EXE.
As I explain here, there is an additional alternative when using modern Git for Windows' bash
MSYS_NO_PATHCONV=1 cmd /c echo test
Explanation of each attempt
TL;DR
The unfortunate answer is in Windows, there are many ways arguments can be parsed, and you have to format your output in bash in such a way that is will be reparsed by the windows program it the way it expects
Second, third, and forth attempts are all actually identical
This is the same as (in cmd) > cmd "/c echo test". Windows cmd only uses " quotes, so somewhere between the runtimes, your (in bash) $ cmd '/c echo test' converts all the arguments to "/c echo test" which is happily parses.
Since from a bash point of view, the 2nd/3rd/4th attempt are all the same, they all give the same response. The surprise " is due to how windows parsing only using " and not ', hence it is the same as > cmd "/c echo test"
Fifth attempt
$ cmd "/c echo" test is the same as > cmd /c echo" test. (I'm guessing: The space after the /c is optional, so cmd isn't confused by /c echo being the space being literal due to the first quote.) So it is trying to execute the command echo" test which doesn't exist. The space is interpreted as literal because of the quote. Likewise, if you had done $ cmd "/c echo "test you would get the output "test, because the space is no longer being treats as literal, and no longer part of the command echo
Note: > cmd "/c echo" test and > cmd /c echo" test error the same. My guess here is that cmd parsed everything after the /c on its own, so the initial " has no affect, as parsing starts all over again. Chalk that up to special cmd weirdness.
This can actually be reproduced using python for windows, which has nothing to do with msys/mingw/git/bash/glibc/etc...
python -c "import subprocess; subprocess.Popen(['cmd', '/c echo test'])"
I noticed git-bash treats the /c argument like a C: drive:
C:\Windows\system32\cmd.exe C:/ echo test
As dbenham found double quotes are added. This echos test" for example:
cmd /c\ echo\ test
I needed the same line (script) to work in git-bash as well as Cygwin Bash. The only ways that work are
cmd /c\ echo\ test\&rem\
(note that this line needs to end in a space), and
cmd << EOC
echo test
EOC
So escape every space after the /c and add \&rem\  at the end of the line (including the trailing space), or just wrap the command in a here document.
All this probably depends on the version of git-bash and the specific commands. :-(
Because you mention that you're using the Git for Windows bundle, I figured I'd point out that it includes winpty, which seems to be quite readable.
$ winpty echo test
test
$ site="Default Web Site"
$ winpty 'C:\Windows\System32\inetsrv\appcmd' list site "${site}" /text:ID
1
This seems to work under 1.9.5.msysgit.1
!foo=`bar`
cmd //c \\\\unc-path\\with\\slashes -args \"Quoted Arguments $foo\"

Can command aliases be added to a DOS shell automatically?

Is there a way to make all DOS shells on my Windows 7 system have this command alias?
doskey h=doskey /history
Is this possible, in the same way that a Bash shell can load a .bash_profile ? I am looking for an answer that does not require PowerShell.
Well DOS isn't really the right word here. In current versions of Windows, you have the CMD.exe shell that has many of the same commands as DOS (dir, copy, etc). You may also have PowerShell. In PowerShell it is easy to configure an alias to always be available. Create a file called $home\Documents\WindowsPowerShell\profile.ps1 and create your alias like so:
New-Alias h Get-History # Don't execute as it already exists
However, PowerShell has already created this particular alias for you. Just open PowerShell, execute a few commands and then execute h.
As for CMD.exe this blog post describes how to configure CMD.exe to do the same.
In short: No. The command processors (cmd.exe and command.com) do not support aliases as you know them from bash and other shells.
Longer answer: you could create a "fake" alias by crafting clever batch files that take the arguments (%1 etc.) and pass them along to to the real command. This has the potential to break down in many glorious ways but it might provide a serviceable workaround in your situation.
Based on Keith Hills answer, here is the batch file I created to do this:
#ECHO OFF
:: to install, place this dos_profile.bat script in the location you want
:: it to reside and then run this batch script with the argument "register"
ECHO Commands defined by dos_profile.bat : F7, h, ls, cp, mv
IF "%1"=="register" (
REG.exe ADD "HKCU\Software\Microsoft\Command Processor\Autorun" /ve /t REG_SZ /d "%CD%\dos_profile.bat" /f
ECHO The DOS profile is registered. Load a new command prompt and test a command.
)
#DOSKEY LS=DIR $*
#DOSKEY CP=COPY $*
#DOSKEY MV=MOVE $*
#DOSKEY H=DOSKEY /HISTORY

How do I run two commands in one line in Windows CMD?

I want to run two commands in a Windows CMD console.
In Linux I would do it like this
touch thisfile ; ls -lstrh
How is it done on Windows?
Like this on all Microsoft OSes since 2000, and still good today:
dir & echo foo
If you want the second command to execute only if the first exited successfully:
dir && echo foo
The single ampersand (&) syntax to execute multiple commands on one line goes back to Windows XP, Windows 2000, and some earlier NT versions. (4.0 at least, according to one commenter here.)
There are quite a few other points about this that you'll find scrolling down this page.
Historical data follows, for those who may find it educational.
Prior to that, the && syntax was only a feature of the shell replacement 4DOS before that feature was added to the Microsoft command interpreter.
In Windows 95, 98 and ME, you'd use the pipe character instead:
dir | echo foo
In MS-DOS 5.0 and later, through some earlier Windows and NT versions of the command interpreter, the (undocumented) command separator was character 20 (Ctrl+T) which I'll represent with ^T here.
dir ^T echo foo
A quote from the documentation:
Source: Microsoft, Windows XP Professional Product Documentation, Command shell overview
Also: An A-Z Index of Windows CMD commands
Using multiple commands and conditional processing symbols
You can run multiple commands from a single command line or script using conditional processing symbols. When you run multiple commands with conditional processing symbols, the commands to the right of the conditional processing symbol act based upon the results of the command to the left of the conditional processing symbol.
For example, you might want to run a command only if the previous command fails. Or, you might want to run a command only if the previous command is successful.
You can use the special characters listed in the following table to pass multiple commands.
& [...]
command1 & command2
Use to separate multiple commands on one command line. Cmd.exe runs the first command, and then the second command.
&& [...]
command1 && command2
Use to run the command following && only if the command preceding the symbol is successful. Cmd.exe runs the first command, and then runs the second command only if the first command completed successfully.
|| [...]
command1 || command2
Use to run the command following || only if the command preceding || fails. Cmd.exe runs the first command, and then runs the second command only if the first command did not complete successfully (receives an error code greater than zero).
( ) [...]
(command1 & command2)
Use to group or nest multiple commands.
; or ,
command1 parameter1;parameter2
Use to separate command parameters.
& is the Bash equivalent for ; ( run commands) and && is the Bash equivalent of && (run commands only when the previous has not caused an error).
If you want to create a cmd shortcut (for example on your desktop) add /k parameter (/k means keep, /c will close window):
cmd /k echo hello && cd c:\ && cd Windows
You can use & to run commands one after another. Example: c:\dir & vim myFile.txt
You can use call to overcome the problem of environment variables being evaluated too soon - e.g.
set A=Hello & call echo %A%
A number of processing symbols can be used when running several commands on the same line, and may lead to processing redirection in some cases, altering output in other case, or just fail. One important case is placing on the same line commands that manipulate variables.
#echo off
setlocal enabledelayedexpansion
set count=0
set "count=1" & echo %count% !count!
0 1
As you see in the above example, when commands using variables are placed on the same line, you must use delayed expansion to update your variable values. If your variable is indexed, use CALL command with %% modifiers to update its value on the same line:
set "i=5" & set "arg!i!=MyFile!i!" & call echo path!i!=%temp%\%%arg!i!%%
path5=C:\Users\UserName\AppData\Local\Temp\MyFile5
cmd /c ipconfig /all & Output.txt
This command execute command and open Output.txt file in a single command
So, I was trying to enable the specific task of running RegAsm (register assembly) from a context menu. The issue I had was that the result would flash up and go away before I could read it. So I tried piping to Pause, which does not work when the command fails (as mentioned here Pause command not working in .bat script and here Batch file command PAUSE does not work). So I tried cmd /k but that leaves the window open for more commands (I just want to read the result). So I added a pause followed by exit to the chain, resulting in the following:
cmd /k C:\Windows\Microsoft.NET\Framework\v4.0.30319\regasm.exe "%1" /codebase \"%1\" & pause & exit
This works like a charm -- RegAsm runs on the file and shows its results, then a "Press any key to continue..." prompt is shown, then the command prompt window closes when a key is pressed.
P.S. For others who might be interested, you can use the following .reg file entries to add a dllfile association to .dll files and then a RegAsm command extension to that (notice the escaped quotes and backslashes):
[HKEY_CLASSES_ROOT\.dll]
"Content Type"="application/x-msdownload"
#="dllfile"
[HKEY_CLASSES_ROOT\dllfile]
#="Application Extension"
[HKEY_CLASSES_ROOT\dllfile\Shell\RegAsm]
#="Register Assembly"
[HKEY_CLASSES_ROOT\dllfile\Shell\RegAsm\command]
#="cmd /k C:\\Windows\\Microsoft.NET\\Framework\\v4.0.30319\\regasm.exe \"%1\" /codebase \"%1\" & pause & exit"
Now I have a nice right-click menu to register an assembly.
In windows, I used all the above solutions &, && but nothing worked
Finally ';' symbol worked for me
npm install; npm start
Well, you have two options: Piping, or just &:
DIR /S & START FILE.TXT
Or,
tasklist | find "notepad.exe"
Piping (|) is more for taking the output of one command, and putting it into another. And (&) is just saying run this, and that.
In order to execute two commands at the same time, you must put an & (ampersand) symbol between the two commands. Like so:
color 0a & start chrome.exe
Cheers!
I try to have two pings in the same window, and it is a serial command on the same line. After finishing the first, run the second command.
The solution was to combine with start /b on a Windows 7 command prompt.
Start as usual, without /b, and launch in a separate window.
The command used to launch in the same line is:
start /b command1 parameters & command2 parameters
Any way, if you wish to parse the output, I don't recommend to use this.
I noticed the output is scrambled between the output of the commands.
Use & symbol in windows to use command in one line
C:\Users\Arshdeep Singh>cd Desktop\PROJECTS\PYTHON\programiz & jupyter notebook
like in linux
we use,
touch thisfile ; ls -lstrh
I was trying to create batch file to start elevated cmd and to make it run 2 separate commands.
When I used & or && characters, I got a problem. For instance, this is the text in my batch file:
powershell.exe -Command "Start-Process cmd \"/k echo hello && call cd C:\ \" -Verb RunAs"
I get parse error:
After several guesses I found out, that if you surround && with quotes like "&&" it works:
powershell.exe -Command "Start-Process cmd \"/k echo hello "&&" call cd C:\ \" -Verb RunAs"
And here's the result:
May be this'll help someone :)
No, cd / && tree && echo %time%. The time echoed is at when the first command is executed.
The piping has some issue, but it is not critical as long as people know how it works.
One more example: For example, when we use the gulp build system, instead of
gulp - default > build
gulp build - build build-folder
gulp watch - start file-watch
gulp dist - build dist-folder
We can do that with one line:
cd c:\xampp\htdocs\project & gulp & gulp watch
Yes there is. It's &.
&& will execute command 2 when command 1 is complete providing it didn't fail.
& will execute regardless.
With windows 10 you can also use scriptrunner:
ScriptRunner.exe -appvscript demoA.cmd arg1 arg2 -appvscriptrunnerparameters -wait -timeout=30 -rollbackonerror -appvscript demoB.ps1 arg3 arg4 -appvscriptrunnerparameters -wait -timeout=30 -rollbackonerror
it allows you to start few commands on one line you want you can run them consecutive or without waiting each other, you can put timeouts and rollback on error.
Try to create a .bat ot .cmd file with those lines using doskey key and $T which is equivalent to & to do several command line in just one line :
touch=echo off $T echo. ^> $* $T dir /B $T echo on
It'll create an empty file.
Example:
touch myfile
In cmd you'll get something like this:
But as mentioned previously by others, it is really advised to use & operator to do many command line in one line from CMD prompt.
Enjoy =)
When you try to use or manipulate variables in one line beware of their content! E.g. a variable like the following
PATH=C:\Program Files (x86)\somewhere;"C:\Company\Cool Tool";%USERPROFILE%\AppData\Local\Microsoft\WindowsApps;
may lead to a lot of unhand-able trouble if you use it as %PATH%
The closing parentheses terminate your group statement
The double quotes don't allow you to use %PATH% to handle the parentheses problem
And what will a referenced variable like %USERPROFILE% contain?
It's simple: just differentiate them with && signs.
Example:
echo "Hello World" && echo "GoodBye World".
"Goodbye World" will be printed after "Hello World".

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