exporting command output to a variable

[John O'Regan]

Dear Batchers,

In a recent post, Jeb mentioned the How SET /P Works article located
at:

http://www.dostips.com/forum/viewtopic.php?f=3&t=2160

which led me (after much Googling) to this thread on an ss64.com
forum:

http://ss64.org/viewtopic.php?id=104

And I began to think to myself how useful it would be to be able to
set
the output of a command to a variable. Like the EXPORT command in
Linux/Unix:

EXPORT var=`cmd`

In fact, there's a free Windows port available (32 and 64-bit) from:

http://www.xeox.com/index.php/en/tools/exportexe

But you can't rely on that software being installed on the system you
find
yourself using at work or for a project, so how about something
written in
pure Batch, and doesn't use temporary files or delayed expansion?

Well, bearing in mind all the caveats outlined in the How SET /P
Works
article, and modifying Dan9999's workaround from the ss64.com forum, I
came up with this rough draft...

:: export.cmd
@echo off & setlocal enableextensions disabledelayedexpansion
if "%~1" neq "" (call :_export "%~1" & goto _bypass)

more /e +[line_no-1] [file.txt] | %ComSpec% /c "%~f0" line
goto _end

:_bypass
if defined line (echo:line="%line%") else echo:^<blank line^>

:_end
endlocal & exit /b 0

:_export
set var=%~1
set /p %var%=
goto :EOF
:: end of export.cmd

Btw, the above also demonstrates how to store the nth line of a CRLF
text
file in a variable.

Apologies if this is old news to you. I tried searching the
archive.
The only result with a promising subject line turned out to be a flame
war
from years back about the future of the newsgroup. Anyways, feel free
to
improve/obfuscate my ver0.1 beyond all recognition. All I ask is that
you add a few comments as you go. Remember that I am a mere
apprentice in
the company of wizards,

toodles,
John

[Todd Vargo]

"John O'Regan" <j.or...@cs.ucc.ie> wrote in message
news:ff92d909-6582-4913...@z18g2000yqb.googlegroups.com...

> Dear Batchers,
>
> In a recent post, Jeb mentioned the How SET /P Works article located
> at:
>
> http://www.dostips.com/forum/viewtopic.php?f=3&t=2160
>
> which led me (after much Googling) to this thread on an ss64.com
> forum:
>
> http://ss64.org/viewtopic.php?id=104
>
> And I began to think to myself how useful it would be to be able to
> set
> the output of a command to a variable. Like the EXPORT command in
> Linux/Unix:
>
> EXPORT var=`cmd`
>
> In fact, there's a free Windows port available (32 and 64-bit) from:
>
> http://www.xeox.com/index.php/en/tools/exportexe
>
> But you can't rely on that software being installed on the system you
> find
> yourself using at work or for a project, so how about something
> written in
> pure Batch, and doesn't use temporary files or delayed expansion?

This can be done using the FOR command to capture the output.

for /f "delims=" %%a in ('the_cmd') do set "var=%%a"

[I'm_HERE]

---------------8<------------------------
@echo off
Setlocal EnableDelayedExpansion
(Set LF=^

)
for /f "delims=" %%o in ('the_cmd') do set txt=!txt!%%o!LF!

echo !txt!

pause
-------------8<--------------------------

[foxidrive]

On 19/09/2011 19:47, I'm_HERE wrote:
> ---------------8<------------------------
> @echo off
> Setlocal EnableDelayedExpansion
> (Set LF=^
>
> )

> for /f "delims=" %%o in ('dir /b') do set txt=!txt!%%o!LF!

>
> echo !txt!
>
> pause
> -------------8<--------------------------

That's interesting. Neat.


--
Regards,
Mic

[John O'Regan]

Dear Todd,

I know a FOR loop can be used to set a variable to the value of a
command's output. And that my workaround is tortuous. But sometimes
it might come in useful because of FOR's limitations. Namely, blank
lines and lines beginning with a semi-colon.

Thanks to I'm_HERE for showing us how to build up a multi-line
variable. But beware of the 8191 character limit,

cheers,
John