What does cmd /C mean? [closed] - command-line

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I can understand cmd but not cmd /c. I was trying to invoke a java program from the current for which I use Runtime.getRuntime().exec("cmd /C java helloworld"); There arises my doubt.

The part you should be interested in is the /? part, which should solve most other questions you have with the tool.
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
C:\>cmd /?
Starts a new instance of the Windows XP command interpreter
CMD [/A | /U] [/Q] [/D] [/E:ON | /E:OFF] [/F:ON | /F:OFF] [/V:ON | /V:OFF]
[[/S] [/C | /K] string]
/C Carries out the command specified by string and then terminates
/K Carries out the command specified by string but remains
/S Modifies the treatment of string after /C or /K (see below)
/Q Turns echo off
/D Disable execution of AutoRun commands from registry (see below)
/A Causes the output of internal commands to a pipe or file to be ANSI
/U Causes the output of internal commands to a pipe or file to be
Unicode
/T:fg Sets the foreground/background colors (see COLOR /? for more info)
/E:ON Enable command extensions (see below)
/E:OFF Disable command extensions (see below)
/F:ON Enable file and directory name completion characters (see below)
/F:OFF Disable file and directory name completion characters (see below)
/V:ON Enable delayed environment variable expansion using ! as the
delimiter. For example, /V:ON would allow !var! to expand the
variable var at execution time. The var syntax expands variables
at input time, which is quite a different thing when inside of a FOR
loop.
/V:OFF Disable delayed environment expansion.

/C Carries out the command specified by the string and then terminates.
You can get all the cmd command line switches by typing cmd /?.

CMD.exe
Start a new CMD shell
Syntax
CMD [charset] [options] [My_Command]
Options
**/C Carries out My_Command and then
terminates**
From the help.

Related

Why is the termination behaviour of vscode different with other GUI program (WinMerge) when invoking from PowerShell?

In Windows PowerShell 5.1, after run & code ., a VSCode window opens, and the control returns back to PowerShell immediately. After the PowerShell exists, the VSCode will not be terminated.
On the other hand, when invoke other external program, such as WinMerge, after run & WinMergeU, a WinMerge window opens, and the control does not return back to PowerShell until WinMerge window is closed. And If PowerShell exists, WinMerge will be terminated.
Why the behaviour is different?
the difference is what is actuall happening:
when you run the command code, you are not really running code.exe. its starting a cmd script that spawns a new code.exe process with whatever arguments you passed it.
to see what a command actually executes, use the command get-command 'yourcommand', or with code get-command code.
this will show the follwing source: C:\Users\{username}\AppData\Local\Programs\Microsoft VS Code\bin\code.cmd.
Opening up this will show you:
#echo off
setlocal
set VSCODE_DEV=
set ELECTRON_RUN_AS_NODE=1
"%~dp0..\Code.exe" "%~dp0..\resources\app\out\cli.js" --ms-enable-electron-run-as-node %*
endlocal
so this means that in both cases you are waiting for execution to end, but for code its a code.cmd script and not actually code.exe.
If you want to start new processes and don't wait for them, you can use the command start-process winmergeu

How to Randomize the browsers from opening a webpage

I have this PowerShell command line which usually opens a webpage via Google Chrome, but I would like that to open randomly with Chrome and Firefox.
start-process -FilePath chrome.exe "www.quora.com"
One PowerShell solution for usage in a PowerShell script or in PowerShell console window is as posted by Santiago Squarzon:
start-process -FilePath ('chrome.exe','firefox.exe'|get-random) "https://www.quora.com"
For understanding the two used PowerShell cmdlets and how they work, open a PowerShell console window, execute there the following commands, and read entirely the two help pages displayed for the two cmdlets very carefully.
help start-process
help get-random
One batch file solution is:
#echo off
setlocal EnableExtensions DisableDelayedExpansion
set /A "Browser=%RANDOM% & 1"
if %Browser% == 0 (set "Browser=chrome") else set "Browser=firefox"
start "" %Browser%.exe "https://www.quora.com"
endlocal
The first two command lines just define the required execution environment completely and creates a new environment variables list as copy of the current environment variables list and the last line just results in restoring the initial execution environment and environment variables list. The second and the last command line could be omitted if it is no problem to depend on Windows defaults or what the process calling this batch file defines as execution environment.
The third line uses an arithmetic expression to apply on a random number a bitwise AND with 1 to get assigned to the environment variable Browser randomly either 0 or 1.
The third line could be also:
set /A Browser=%RANDOM% %% 2
This arithmetic expression divides a random number by two and gets the remainder 0 or 1 assigned to the environment variable Browser.
The fourth line uses an IF condition to redefine the environment variable Browser on having currently the value 0 with the string chrome and otherwise with the string firefox.
The fifth line uses command start to start either chrome.exe or firefox.exe as separate process on which cmd.exe does not wait for self-termination before continuation of processing of the batch file with passing the URL to started executable. "" defines an empty string as optional title for the console window not opened at all as the two browsers are Windows applications with a graphic user interface.
For understanding the used Windows Commands and how they work, open a command prompt window, execute there the following commands, and read entirely all help pages displayed for each command very carefully.
help echo or echo /?
help endlocal or endlocal /?
help if or if /?
help set or set /?
help setlocal or setlocal /?
help start or start /?
See also:
An A-Z Index of Windows CMD commands
An A-Z Index of Windows PowerShell commands
Windows CMD Shell How-to guides and examples
Windows PowerShell How-to guides and examples
Where is "START" searching for executables?
powershell.exe does the same. PowerShell and CMD use the Windows kernel library function CreateProcess to start the Chrome or Firefox process.

Call multiple .bat from another .bat without waiting for one to finish

So, I want to make a script that will execute 2 .bat files and start some .exe files.
However, the .bat files are supposed to keep running.
I have something like this :
pushd tools\wamp64
start wampmanager.exe
pushd ..\..\server\login
call startLoginServer.bat
pushd ..\test
call startTestServer.bat
start "C:\DEV\P2\Test\client" P2.bin
The problem is that call startLoginServer.bat will not exit and therefore, I'm stucked here.
How can I run my 2 .bat files and let them keep running.
(Ideally, I want them to run in 2 different command prompt windows)
Also, there is probably a better way to handle relative path than using pushd if you can correct me on this.
Thanks
You could use:
start "Wamp Manager" /B /D "%~dp0tools\wamp64" wampmanager.exe
start "Login Server" /B /D "%~dp0server\login" startLoginServer.bat
start "Test Server" /B /D "%~dp0server\test" startTestServer.bat
start "Text Client" /B /D "%~dp0" "C:\DEV\P2\Test\client.exe" P2.bin
Run in a command prompt window start /? for help on this command explaining the options.
"..." ... title for new console window which is optional, but must be often specified on program to start is or must be enclosed in double quotes. The START command in last command line in batch file code in question interprets C:\DEV\P2\Test\client as window title. It is also possible to use an empty window title, i.e. "" which is best if the started application is a Windows GUI application on which no console window is opened at all.
/B ... run without opening a new window, i.e. in "background". This option can be omitted to see what the started applications and batch files output to console if the executables are not Windows GUI applications.
/D "..." or also /D"..." defines the directory to set first as current directory before running the command specified next. %~dp0 references the directory of the batch file containing these commands. This path always ends with a backslash. Therefore no backslash must be added on concatenating the directory of the batch file with a file or folder name or path.
Run in a command prompt window call /? for help on %~dp0 explaining how arguments of a batch file can be referenced from within a batch file.
See also the answer on How to call a batch file that is one level up from the current directory? explaining in total four different methods to call or run a batch file from within a batch file.
Finally read also the Microsoft documentations about the Windows kernel library function CreateProcess and the structure STARTUPINFO used by cmd.exe on every execution of an executable without or with usage of its internal command start. The options of start become more clear on having full knowledge about the kernel function and the structure used on Windows to run a program.

running daemon in background in scala console

I'm trying to run a daemon in the scala console in the background. I can get it to run the program but it locks the console window when it is running, and therefore forces me to use a separate window to stop the daemon to unlock the original console. I'm running the scala console in a windows powershell through sbt.
I can use the command prompt to successfully run the program in the background using: start /b program, but running ("start /b program").! in the scala console fails.
This will run the program in scala console but will lock the window:
("cmd /c start program").!
How can I get the program to successfully run in the background so I still have access to the current console?
I've been fiddling with /E:ON using /b as an extension of start to no avail.
These are results from cmd /?
Microsoft Windows XP [Version 5.1.2600]
(C) Copyright 1985-2001 Microsoft Corp.
C:\>cmd /?
Starts a new instance of the Windows XP command interpreter
CMD [/A | /U] [/Q] [/D] [/E:ON | /E:OFF] [/F:ON | /F:OFF] [/V:ON | /V:OFF]
[[/S] [/C | /K] string]
/C Carries out the command specified by string and then terminates
/K Carries out the command specified by string but remains
/S Modifies the treatment of string after /C or /K (see below)
/Q Turns echo off
/D Disable execution of AutoRun commands from registry (see below)
/A Causes the output of internal commands to a pipe or file to be ANSI
/U Causes the output of internal commands to a pipe or file to be
Unicode
/T:fg Sets the foreground/background colors (see COLOR /? for more info)
/E:ON Enable command extensions (see below)
/E:OFF Disable command extensions (see below)
/F:ON Enable file and directory name completion characters (see below)
/F:OFF Disable file and directory name completion characters (see below)
/V:ON Enable delayed environment variable expansion using ! as the
delimiter. For example, /V:ON would allow !var! to expand the
variable var at execution time. The var syntax expands variables
at input time, which is quite a different thing when inside of a FOR
loop.
/V:OFF Disable delayed environment expansion.
You should use forking in SBT, that's exactly what it is for.
For your case set this setting in your SBT build:
fork in run := true
By default stdin will not be connected to your forked process, to enable it do:
connectInput in run := true
Figured it out thanks to #som-snytt's link to #michael.kebe's answer on this SO entry: How does the “scala.sys.process” from Scala 2.9 work?
val pb = Process("""program""").run
Does exactly what I wanted

How to force invoked command's STDOUT into invoking cmd.exe's STDOUT?

Context: Oracle Enterprise Manager has a feature to "execute host command." If into that feature I enter "dir c:\temp" then the output window echos the command and then shows a directory listing. If into that feature I enter "powershell dir c:\temp" the output window shows only the echo'd command. No directory listing. If on the target machine I enter those two commands in both cases I get the echo'd command followed by a directory listing.
I hypothesize that what I see in the cmd.exe window on the client blends two stdout streams: one from the cmd.exe itself and one from the invoked process (powershell dir c:\temp). The Oracle thing seems to recognize only the cmd.exe's stdout.
Is there some way I can force the stdout from the invoked process to be in the cmd.exe's stdout stream so that Oracle will recognize it and the thing I am trying to build will work?
I don't think you can directly pipe the output from one program back into STDOUT of a parent cmd.exe - assuming that is what Oracle is doing at some level.
That being said, you could try something clever like the following:
cmd /c "powershell -Command ""& echo Hello" > %TEMP%\a.txt & TYPE %TEMP\a.txt
Basically this is capturing the output from PowerShell, placing it in a temporary file, then dumping that file back onto STDOUT in cmd.exe. A nice touch would be cleaning up the temp file with a & DEL %TEMP%\a.txt on the end of the command.
You will probably need to toy around with the command line to account for any quirks in how Oracle is passing things along - my guess is that it is invoking cmd.exe /c directly so you can probably leave that part off.