Please note: This question is not about how to echo without a newline. It's about to pipe a variable without a newline and store the result in another variable. Please don't mark this question as duplicate to other questions answering only how to remove newlines!
I have a variable a which I want to pass to a program (let's use more for the sake of this example), and its result should be stored into another variable b. This is to prevent the creation of temporary files. Sticking some answers from other questions here together, this could be achieved by something like this:
FOR /f "tokens=*" %%t IN ('ECHO %a% ^| MORE') DO SET b=%%t
Which works -- BUT will add another newline on my variable! So I tried the following tricks you find on stackoverflow/superuser to prevent the newline. If you do these without the loop, they work perfectly! But once you put them in a loop, they fail:
FOR /f "tokens=*" %%t IN ('ECHO ^| SET /p="%a%" ^| MORE') DO SET b=%%t
FOR /f "tokens=*" %%t IN ('^<NUL SET /p="%a%" ^| MORE') DO SET b=%%t
It will always say The syntax of the command is incorrect. What am I missing? Please help me!
If you run your command
FOR /f "delims=" %%t IN ('^<NUL SET /p="%a%" ^| more ') DO SET "b=%%t"
with echo ON you will see the equal sign in the set command has vanished, it has been removed by the parser leaving an incorrect command.
You have two options:
FOR /f "delims=" %%t IN ('^<NUL SET /p^="%a%" ^| more ') DO SET "b=%%t"
FOR /f "delims=" %%t IN ('^<NUL SET /p"=%a%" ^| more ') DO SET "b=%%t"
The first one escapes the equal sign. The second one quotes it.
Related
I've been trying to make a script that installs the current nvidia driver, I've gone pretty far but there's one thing missing
I'm trying to use nvidia-smi to find the driver version and here's the command output
C:\>nvidia-smi --query-gpu=driver_version --format=csv
driver_version
457.30
I've been trying to set 457.30 in %driver% here's what I got so far
FOR /F "tokens=* skip=1" %%g IN ('nvidia-smi --query-gpu=driver_version --format=csv') do (SET "driver=%%g")
I also tried a combination with findstr but that ended up being a disaster
for /F "tokens=* skip=1" %%g in ('nvidia-smi --query-gpu=driver_version --format=csv ^| findstr "."') do set driver=%%g
In any case, %%g and %driver% return as empty.
echo %driver%
returns
C:\>echo
ECHO is on.
Any ideas?
Thank you for your cooperation.
Your variable isn't getting set because right now your nvidia-smi command is throwing an error (to stdout, curiously) but skip=1 is skipping over it so there's nothing left to set the variable to.
= is one of the default delimiters for strings and so both of the = symbols in your command need to be escaped for your query to be executed correctly.
#echo off
for /F "delims=" %%g IN ('nvidia-smi --query-gpu^=driver_version --format^=csv ^| find "."') do set "driver=%%g"
echo %driver%
Linked:
Best free resource for learning advanced batch-file usage?
Dealing with quotes in Windows batch scripts
This appears to be one of those maddening quoting issues. In this example program:
#echo off
set wmicpath=%windir%\System32\wbem\wmic.exe
for /f "usebackq" %%a in (`%wmicpath% COMPUTERSYSTEM GET SystemType ^| findstr /I "x64"`) do (
echo %%a
)
The program runs just fine. Unless you try to quote the wmicpath. Imagine if you will that it contains a long path name. Then you should quote it. But I cannot quite get it to work. This fails:
for /f "usebackq" %%a in (`"%wmicpath%" COMPUTERSYSTEM GET SystemType ^| findstr /I "x64"`) do (
but this works!:
for /f "usebackq" %%a in (`"%wmicpath%" COMPUTERSYSTEM GET SystemType ^| findstr /I x64`) do (
as does this:
for /f "usebackq" %%a in (`"%wmicpath%" COMPUTERSYSTEM GET SystemType`) do (
There's something really odd about matching quotes in a for command. You can quote a command as long as you don't start quoting elsewhere...
Is it possible? I tried escaping at various points but I'm not sure about the escaping rules when quotes are involved...
Edit: I think this link might be the issue (ie: it's a bug): Pipe in for loop breaks double quoted variables
#echo off
setlocal enableextensions disabledelayedexpansion
set "wmicpath=%windir%\System32\wbem\wmic.exe"
for /f "usebackq delims=" %%a in (`
^""%wmicpath%" COMPUTERSYSTEM GET SystemType ^| findstr /I "x64"^"
`) do (
echo %%a
)
If you look at the start and end of the inner command, you will see two additional ^" (a escaped double quote). Your problem is that the for command is spawning a separate instance of cmd to handle the inner command, and this separate instance is removing the initial and final double quotes.
Why escaped quotes? To avoid this additional quotes being paired with the double quotes in the command that could lead to some other parsing problems.
You can run cmd /? to obtain the help page (sorry, i have a spanish locale so i will not include the output here). You will see a section about the /C and /K usage explaining quote removal behaviour.
First of all I would change the command, WMIC allows you to use a query language LIKE operator which would in this case remove the need to pipe anything.
#Echo Off
Set "WMIC=%SystemRoot%\System32\Wbem\wmic.exe"
For /F "UseBackQ Skip=1" %%a In (
`""%WMIC%" ComputerSystem Where "SystemType Like 'x64%%'" Get SystemType"`
) Do For %%b In (%%a) Do Echo=%%b
Timeout -1
Then I may even change the format of the command such that I don't use back quotes.
#Echo Off
Set "WMIC=%SystemRoot%\System32\Wbem\wmic.exe"
For /F "Skip=1" %%a In (
'""%WMIC%" ComputerSystem Where (SystemType Like "x64%%") Get SystemType"'
) Do For %%b In (%%a) Do Echo=%%b
Timeout -1
Whilst this doesn't directly answer the question in the subject title, it does allow for your particular command to work correctly.
However neither are necessary to your particular command example, because you do not need the for loop to echo that output:
#Echo Off
Set "WMIC=%SystemRoot%\System32\Wbem\wmic.exe"
"%WMIC%" ComputerSystem Get SystemType|Find /I "x64"
Timeout -1
Change Find to FindStr if you feel the need.
>x64.txt ECHO x64
for /f "usebackq" %%a in (`"%wmicpath%" COMPUTERSYSTEM GET SystemType ^| findstr /I /g:x64.txt`) do (
might be a work-around, depending on your actual application and preferences.
I'm trying to write a batch script that obtains (among other things) a list of all of the disk drives the computer has. The basic code looks something like this:
REM Build the list of disk drives to monitor
SETLOCAL enabledelayedexpansion
FOR /f "skip=1 tokens=1 delims=:" %%a in ('"WMIC logicaldisk WHERE drivetype=3 GET deviceid"') do (
SET "DISK_DATABASES=!DISK_DATABASES!%%a|"
SET "DRIVES_TO_MONITOR=!DRIVES_TO_MONITOR!%%a:\\|"
)
I pretty obviously build two lists with slightly different formats for use later. When I run this, however, the output I get looks something like this:
C|D|E||
C:\\|D:\\|E:\\|:\\|
Now, I expect the trailing pipe in both cases and I can manage that, but I'm really confused why there is an extra blank entry in there. If I run the wmic command manually, I can see that there is indeed a blank line at the end of the output, but my understanding is that /f was specifically supposed to ignore blank lines.
If I turn ECHO on, it looks like that last line is just coming in as a carriage return/newline or similar. Is there a way to do what I'm expecting? Am I missing something? I tried to write an if condition in the loop to exclude this last line, but it was... funky and never worked. I appreciate any/all help.
I just came over this topic. I've been using findstr /v to exclude empty lines:
FOR /f "usebackq skip=1 tokens=1 delims=:" %%a in (`WMIC logicaldisk WHERE "drivetype=3" GET deviceid ^| findstr /v /r "^$"`) do (
In this case the last iteration produces not an empty item, and you get your output of C|D|E|| only with echo %DISK_DATABASES%,
but echo !DISK_DATABASES! will output ||D|E|??
That's because the last element is a single <CR> character.
And <CR> characters are directly removed after the percent expansion, but not with delayed expansion.
You could avoid this, using the percent expansion to remove them
setlocal EnableDelayedExpansion
FOR /f "skip=1 tokens=1 delims=:" %%a in ('"WMIC logicaldisk WHERE drivetype=3 GET deviceid"') do (
set "item=%%a"
call :removeCR
if not "!item!"=="" (
SET "DISK_DATABASES=!DISK_DATABASES!!item!|"
SET "DRIVES_TO_MONITOR=!DRIVES_TO_MONITOR!!item!:\\|"
)
)
goto :eof
:removeCR
:removeCR
set "Item=%Item%"
exit /b
According to http://ss64.com/nt/for_f.html
Many of the newer commands and utilities (e.g. WMIC) output text files in unicode format, these cannot be read by the FOR command which expects ASCII.
To convert the file format use the TYPE command.
So it appears that WMIC and FOR don't play nice together.
I discovered a more efficient and more reliable method to strip the unwanted <CR> from the end of each line. No temp file, and no CALL needed.
I don't understand the mechanism of how FOR /F converts the WMIC unicode output into ASCII. Normally FOR /F cannot read unicode. But however it works, each converted line ends with <CR><CR><LF>. FOR /F breaks lines at each <LF>, and then if the last character in the line is <CR> it strips that last <CR>, in this case leaving behind the unwanted <CR>.
The solution is to simply pass each line through one more FOR /F :-)
#echo off
setlocal enableDelayedExpansion
for /f "skip=1 delims=" %%A in (
'wmic logicaldisk where "drivetype=3" get deviceid'
) do for /f "tokens=1 delims=:" %%B in ("%%A") do (
set "disk_databases=!disk_databases!%%B|"
set "drives_to_monitor=!drives_to_monitor!%%B:\\|"
)
This method is more reliable then using normal expansion because you don't have to worry about quoting or escaping special characters. For example, The CALL method that uses normal expansion cannot handle a string like "this & that" & the other. But this method has no problem with such a string.
Add ^| findstr . and you will get only not blank lines
REM Build the list of disk drives to monitor
SETLOCAL enabledelayedexpansion
FOR /f "skip=1 tokens=1 delims=:" %%a in (
'"WMIC logicaldisk WHERE drivetype=3 GET deviceid" ^| findstr .') do (
SET "DISK_DATABASES=!DISK_DATABASES!%%a|"
SET "DRIVES_TO_MONITOR=!DRIVES_TO_MONITOR!%%a:\|"
)
My standard idiom for dealing with this is to write the output from WMIC to a temp file, then use TYPE (which reduces UTF16 to ASCII) to feed that into FOR, like this:
:: Standard environment setup
setlocal enabledelayedexpansion
:: Every variable whose name starts with "tf" will identify a temporary
:: file - remove any such variables inherited from the parent environment
for /f %%V in ('set tf') do set %%V=
:: Create some temporary filenames. Prefix all of them with this script's
:: own name to avoid clashes with those owned by other scripts.
for /l %%I in (1,1,4) set tf%%I="%temp%\%~n0-temp%%I.txt"
:: Use temp file to work around coding mismatch between WMIC out and FOR in
wmic product where "name like 'Microsoft Office %% 2010'" get packagecache >!tf1!
for /f "skip=1" %%P in ('type !tf1!') do if exist "%%~P" msiexec /x "%%~P" /passive /norestart
:: Before quitting script, clean up temporary files
for /f %%V in ('set tf') do if exist "%%~V" del /f /q "%%~V"
endlocal
Run the following command:
wmic blah /value | find "=" >> wherever
Output will be:
field=value
Note that there will be no extra lines.
Is it possible to use a piped stdin stream inside a batch file?
I want to be able to redirect the output of one command into my batch file process.bat list so:
C:\>someOtherProgram.exe | process.bat
My first attempt looked like:
echo OFF
setlocal
:again
set /p inputLine=""
echo.%inputLine%
if not (%inputLine%)==() goto again
endlocal
:End
When I test it with type testFile.txt | process.bat it prints out the first line repeatedly.
Is there another way?
set /p doesn't work with pipes, it takes one (randomly) line from the input.
But you can use more inside of an for-loop.
#echo off
setlocal
for /F "tokens=*" %%a in ('more') do (
echo #%%a
)
But this fails with lines beginning with a semicolon (as the FOR-LOOP-standard of eol is ;).
And it can't read empty lines.
But with findstr you can solve this too, it prefix each line with the linenumber, so you never get empty lines.
And then the prefix is removed to the first colon.
#echo off
setlocal DisableDelayedExpansion
for /F "tokens=*" %%a in ('findstr /n "^"') do (
set "line=%%a"
setlocal EnableDelayedExpansion
set "line=!line:*:=!"
echo(!line!
endlocal
)
Alternatively, on some environments (like WinRE) that don't include findstr, an alternative with find.exe might suffice. find will accept a null search string "", and allows search inversion. This would allow something like this:
#echo off
setlocal DisableDelayedExpansion
for /F "tokens=*" %%a in ('find /v ""') do (
...
The set "line=!line:*:=!" syntax is:
set requires one parameter that is a=b.
If a contains a space or something, you'll have to use the quotation marks around this parameter. Here I don't see any
!line:*:=!
For this syntax, you can type 'set /?' to see the official description on using variables.
!var! is like %var%, to get the value. But !var! means delayed expansion.
line var name
the first : variable modification mark.
**:= **:=(empty), replace the string in the variable's value matches "*:"(virtually from the string start to first : occurence) with (empty), i.e. delete the substring from start to first colon.
FOR /F "tokens=1* delims=]" %%A IN ('FIND /N /V ""') DO (
> CON ECHO.%%B
>> %File% ECHO.%%B
)
Source here: http://www.robvanderwoude.com/unixports.php#TEE
Alternatively, on some environments (like WinRE) that don't include findstr, an alternative with find.exe might suffice. find will accept a null search string "", and allows search inversion. This would allow something like this:
#echo off
setlocal DisableDelayedExpansion
for /F "tokens=*" %%a in ('find /v ""') do (
set "line=%%a"
echo(!line!
)
for deleting files, I will be using the code below to remove the oldest file in the directory and run it every day. It came from the question of mine.
Applying to the original batch script:
SET BACKUPDIR=C:\PATH\TO\BACKUPS
FOR /F %%i IN ('DIR /B /O-D %BACKUPDIR%') DO SET OLDEST=%%i
DEL %BACKUPDIR%\%OLDEST%
Something such as that checks if the file amount is 21, if so delete the latest one:
SET BACKUPDIR=C:\test
SET countfiles = dir BACKUPDIR /b | find /v /c "::"
if countfiles > 21
FOR /F %%i IN ('DIR /B /O-D %BACKUPDIR%') DO SET OLDEST=%%i
DEL %BACKUPDIR%\%OLDEST%
EDIT: Sorry for forgetting the question, my attempt was failing, I would be greatful for any way to direct how to make it work.
first, it seems set does not like spaces between the variable and the = sign: if you put a space, the variable name will include a space. so you must remove the space to properly define the variable name.
plus, your syntax for capturing the output of the command into a variable is wrong. the only way i am aware of (after desperately searching stackoverflow for the answer) is to use a for loop trick to use a temporary variable (see this question for more details). actually, you also need to escape the pipe for the command to be parsed correctly.
then, when the variable tested in the if expression does not exists, the results is always true, so make sure the variable exists. by removing the space as said above, the name in the if expression will match your variable name, and the test will execute properly.
then you forgot to make a block around the 2 last commands. actually, you are testing if you have more than 21 files and compute the oldest if it is true, then you ALWAYS delete the oldest.
also, the greater than operator > may be understood as a redirection. you may need to use the GTR operator.
SET BACKUPDIR=C:\test
FOR /F %%i in ('dir BACKUPDIR /b ^| find /v /c "::"') DO SET countfiles=%%i
if countfiles GTR 21 (
FOR /F %%i IN ('DIR /B /O-D %BACKUPDIR%') DO SET OLDEST=%%i
DEL %BACKUPDIR%\%OLDEST%
)
That's not working...you can't set 'normal' variables within a for-loop. I had the same problem some days ago and solved it with this blog entry.
Basically, you need to set SETLOCAL ENABLEDELAYEDEXPANSION and then use ! instead of %...
set FILES=
for /f %%a IN (‘dir /b *.txt’) do set FILES=!FILES! %%a
echo %FILES%
So, this should work for you:
SETLOCAL ENABLEDELAYEDEXPANSION
SET OLDEST=
FOR /F %%i IN ('DIR /B /O-D %BACKUPDIR%') DO SET OLDEST=%%i
DEL %BACKUPDIR%\%OLDEST%