To reference a variable in Windows, use %varname% (with prefix and suffix of '%' ). For example, you can use the echo command to print the value of a variable in the form " echo %varname% ".
If you can wait until the command line app has finished running to be able to read the output then it is very easy. Change the command to run to be something like "cmd.exe /c test.exe > test_output. txt". This causes the Windows Command Prompt to execute your test.exe app and redirect the output into test_output.
By default, variables are global to your entire command prompt session. Call the SETLOCAL command to make variables local to the scope of your script. After calling SETLOCAL, any variable assignments revert upon calling ENDLOCAL, calling EXIT, or when execution reaches the end of file (EOF) in your script.
The humble for command has accumulated some interesting capabilities over the years:
D:\> FOR /F "delims=" %i IN ('date /t') DO set today=%i
D:\> echo %today%
Sat 20/09/2008
Note that "delims="
overwrites the default space and tab delimiters so that the output of the date command gets gobbled all at once.
To capture multi-line output, it can still essentially be a one-liner (using the variable lf as the delimiter in the resulting variable):
REM NB:in a batch file, need to use %%i not %i
setlocal EnableDelayedExpansion
SET lf=-
FOR /F "delims=" %%i IN ('dir \ /b') DO if ("!out!"=="") (set out=%%i) else (set out=!out!%lf%%%i)
ECHO %out%
To capture a piped expression, use ^|
:
FOR /F "delims=" %%i IN ('svn info . ^| findstr "Root:"') DO set "URL=%%i"
If you have to capture all the command output you can use a batch like this:
@ECHO OFF
IF NOT "%1"=="" GOTO ADDV
SET VAR=
FOR /F %%I IN ('DIR *.TXT /B /O:D') DO CALL %0 %%I
SET VAR
GOTO END
:ADDV
SET VAR=%VAR%!%1
:END
All output lines are stored in VAR separated with "!".
But if only a single-line console-output is expected, try:
@ECHO off
@SET MY_VAR=
FOR /F %%I IN ('npm prefix') DO @SET "MY_VAR=%%I"
@REM Do something with MY_VAR variable...
@John: is there any practical use for this? I think you should watch PowerShell or any other programming language capable to perform scripting tasks easily (Python, Perl, PHP, Ruby)
To get the current directory, you can use this:
CD > tmpFile
SET /p myvar= < tmpFile
DEL tmpFile
echo test: %myvar%
It's using a temp-file though, so it's not the most pretty, but it certainly works! 'CD' puts the current directory in 'tmpFile', 'SET' loads the content of tmpFile.
Here is a solution for multiple lines with "array's":
@echo off
rem ---------
rem Obtain line numbers from the file
rem ---------
rem This is the file that is being read: You can replace this with %1 for dynamic behaviour or replace it with some command like the first example i gave with the 'CD' command.
set _readfile=test.txt
for /f "usebackq tokens=2 delims=:" %%a in (`find /c /v "" %_readfile%`) do set _max=%%a
set /a _max+=1
set _i=0
set _filename=temp.dat
rem ---------
rem Make the list
rem ---------
:makeList
find /n /v "" %_readfile% >%_filename%
rem ---------
rem Read the list
rem ---------
:readList
if %_i%==%_max% goto printList
rem ---------
rem Read the lines into the array
rem ---------
for /f "usebackq delims=] tokens=2" %%a in (`findstr /r "\[%_i%]" %_filename%`) do set _data%_i%=%%a
set /a _i+=1
goto readList
:printList
del %_filename%
set _i=1
:printMore
if %_i%==%_max% goto finished
set _data%_i%
set /a _i+=1
goto printMore
:finished
But you might want to consider moving to another more powerful shell or create an application for this stuff. It's stretching the possibilities of the batch files quite a bit.
you need to use the SET
command with parameter /P
and direct your output to it.
For example see http://www.ss64.com/nt/set.html. Will work for CMD, not sure about .BAT files
From a comment to this post:
That link has the command "
Set /P _MyVar=<MyFilename.txt
" which says it will set_MyVar
to the first line fromMyFilename.txt
. This could be used as "myCmd > tmp.txt
" with "set /P myVar=<tmp.txt
". But it will only get the first line of the output, not all the output
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