Exit status of tasklist in batch file?

2023-02-10 10:44 问答作者：

I am executing foll开发者_如何学编程owing command in a label inside a batch file:

tasklist.exe /FI "USERNAME eq %USERDOMAIN%\%USERNAME%" /FI "IMAGENAME eq %1" /FI "PID eq %2" 2>nul && echo errorl:%errorlevel%

%1 is process running and %2 is its PID. Even if process and its PID matches or doesnt matches, I m getting "errorl:1" in o/p.

I am not sure whats wrong here. Any idea?

You could pipe tasklist through the find command and get an errorlevel off of it.

Example:

tasklist | find "firefox.exe"
echo Error level = %ERRORLEVEL%

REM If firefox is running, the errorlevel is set to 0
REM If firefox is not running, errorlevel is set to 1

In my opinion, you can't use errorlevel at all,
because tasklist always returns a 0 even if the pid isn't found.

I suppose, you have to parse the output of tasklist.
To fetch the output of a command, FOR /F is a good choice.

To avoid problems wth the quoting in the FOR /F, I build first a cmd variable which is expanded with delayed expansion to avoid any side effects of special characters.

@echo off
setlocal enableDelayedExpansion

set "cmd=tasklist.exe /FI "USERNAME eq %USERDOMAIN%\%USERNAME%" /FI "IMAGENAME eq %1" /FI "PID eq %2""

for /F "delims=*" %%p in ('!cmd! ^| findstr "%2" ') do (
  echo found %%p
)

%variables% are expanded before executing the line, so %errorlevel% will expand to some old value. (The fact that the code after && executes at all is your clue that the command returned 0)

You options are:

Use %errorlevel% or the more correct IF errorlevel 1 ... on the next line
Call setlocal ENABLEDELAYEDEXPANSION first and then use !errorlevel!

Edit: I guess tasklist is buggy and/or stupid when it comes to exit codes, I wrote some code that does not use the exit code at all:

@echo off
if "%~1"=="SOTEST" (
    start calc
    ping -n 2 localhost >nul
    for /F "tokens=1,2 skip=3" %%A in ('tasklist /FI "IMAGENAME eq calc.exe"') do (
        call "%~0" %%A %%B
    )
    call "%~0" dummy.exe 666
    goto :EOF
)
goto main


:IsTaskRunning
setlocal ENABLEEXTENSIONS&set _r=0
>nul 2>&1 (for /F "tokens=1,2" %%A in ('tasklist /FO LIST %*') do (
    if /I "%%~A"=="PID:" set _r=1
))
endlocal&set IsTaskRunning=%_r%&goto :EOF

:main
call :IsTaskRunning /FI "USERNAME eq %USERDOMAIN%\%USERNAME%" /FI "IMAGENAME eq %1" /FI "PID eq %2"
if %IsTaskRunning% gtr 0 (echo.%1:%2 is running) else (echo.%1:%2 is NOT running)

Run it as test.cmd SOTEST and it prints:

calc.exe:4852 is running
dummy.exe:666 is NOT running

Easy solution to this, given that

 1) you can't get an errorlevel from tasklist, and
 2) you can't directly pipe it to a FIND

Just write it to a file using output redirection and use FIND to check the file. Each time this is run, it will overwrite the previous iteration, so no need to even do any file cleanup. Amazing how many bat/cmd file limitations can be overcome with a simple scratchpad file!!

:TOP
rem swap rems from good to bad to test
set findvar=goodfile.exe          
rem set findvar=badfile.exe
set scratchfile=scratch.txt
tasklist /fi "status eq running" /fi "imagename eq %findvar%">%scratchfile%
type %scratchfile%
pause
echo Looking for %findvar%
find "%findvar%" %scratchfile%
echo Error level = %errorlevel%
pause
IF errorlevel 1 GOTO BAD
IF errorlevel 0 GOTO GOOD
GOTO OTHER

:BAD
 echo Errrlevel 1 - task not found
 PAUSE     
 GOTO TOP
:GOOD
 echo Errrlevel 0 - task is running
 pause
 GOTO TOP
:OTHER
 echo something else ????? you blew it somewhere!

tasklist returns 0 when executes successfully:
If you're looking for existence of some process or some attribute of a process, one method is to supply the attributes to tasklist and check if it returned any process names. If no matching processes are found, it'll return "INFO: No tasks are running which match the specified criteria."

The result of tasklist may be checked either via for command embedding (and parse command output) or filter via find or findstr, which accepts regular expressions & wildcards.

eg. To check if the any process is running with following criteria:

tasklist.exe /FI "USERNAME eq %USERDOMAIN%\%USERNAME%" /FI "IMAGENAME eq %1" /FI "PID eq %2" | find /v "No task" >nul && (echo process exists) || (echo na man).

Above method can also find if any document (window) is open, in addition to the underlying process, like "firefox.exe".
eg. close high speed vpn ad window if/when it pops up without notice: