CALL command vs START with WAIT option

Question

How is the START command with a WAIT option   START  wait notepad exe  START  wait  notepad exe       any different from using a CALL command   CALL notepad exe  CALL notepad exe    Is there a situation where one may behave differently that the other dependending on what is being executed

User · Answer

This is what I found while running batch files in parallel (multiple instances of the same bat file at the same time with different input parameters) :

Lets say that you have an exe file that performs a long task called LongRunningTask.exe

If you call the exe directly from the bat file, only the first call to the LongRunningTask will succed, while the rest will get an OS error "File is already in use by the process"

If you use this command:

start /B /WAIT "" "LongRunningTask.exe" "parameters"

You will be able to run multiple instances of the bat and exe, while still waiting for the task to finish before the bat continues executing the remaining commands. The /B option is to avoid creating another window, the empty quotes are needed in order to the command to work, see the reference below.

Note that if you don´t use the /WAIT in the start, the LongRunningTask will be executed at the same time than the remaining commands in the batch file, so it might create problems if one of these commands requires the output of the LongRunningTask

Resuming :

This can´t run in parallel :

call LongRunningTask.exe

This will run in parallel and will be ok as far as there are no data dependencies between the output of the command and the rest of the bat file :

start /B "" "LongRunningTask.exe" "parameters"

This will run in parallel and wait for the task to finish, so you can use the output :

start /B /WAIT "" "LongRunningTask.exe" "parameters"

Reference for the start command : How can I run a program from a batch file without leaving the console open after the program start?

User · Answer

For exe files  I suppose the differences are nearly unimportant  But to start an exe you don t even need CALL     When starting another batch it s a big difference  as CALL will start it in the same window and the called batch has access  to the same variable context  So it can also change variables which affects the caller     START will create a new cmd exe for the called batch and without  b it will open a new window  As it s a new context  variables can t be shared   Differences  Using start  wait  lt prog gt  - Changes of environment variables are lost when the  lt prog gt  ends - The caller waits until the  lt prog gt  is finished  Using call  lt prog gt  - For exe it can be ommited  because it s equal to just starting  lt prog gt  - For an exe-prog the caller batch waits or starts the exe asynchronous  but the behaviour depends on the exe itself  - For batch files  the caller batch continues  when the called  lt batch-file gt  finishes  WITHOUT call the control will not return to the caller batch  Addendum     Using CALL can change the parameters  for batch and exe files   but only when they contain carets or percent signs   call myProg param1 param  2  param 3    path     Will be expanded to  from within an batch file     myProg param1 param2 param  3  lt content of path gt

User · Answer

This is an old thread  but I have just encountered this situation and discovered a neat way around it  I was trying to run a setup exe  but the focus was returning to the next line of the script without waiting for the setup exe to finish   I tried the above solutions with no luck   In the end  piping the command through more did the trick   setup exe  arguments    more

User · Answer

I think that they should perform generally the same  but there are some differences  START is generally used to start applications or to start the default application for a given file type   That way if you START http   mywebsite com it doesn t do START iexplore exe http   mywebsite com   START myworddoc docx would start Microsoft Word and open myworddoc docx CALL myworddoc docx does the same thing    however START provides more options for the window state and things of that nature  It also allows process priority and affinity to be set   In short  given the additional options provided by start  it should be your tool of choice   START   title     D path    I    MIN    MAX    SEPARATE    SHARED      LOW    NORMAL    HIGH    REALTIME    ABOVENORMAL    BELOWNORMAL      NODE  lt NUMA node gt     AFFINITY  lt hex affinity mask gt     WAIT    B     command program   parameters    title      Title to display in window title bar  path        Starting directory  B           Start application without creating a new window  The             application has  C handling ignored  Unless the application             enables  C processing   Break is the only way to interrupt             the application  I           The new environment will be the original environment passed             to the cmd exe and not the current environment  MIN         Start window minimized  MAX         Start window maximized  SEPARATE    Start 16-bit Windows program in separate memory space  SHARED      Start 16-bit Windows program in shared memory space  LOW         Start application in the IDLE priority class  NORMAL      Start application in the NORMAL priority class  HIGH        Start application in the HIGH priority class  REALTIME    Start application in the REALTIME priority class  ABOVENORMAL Start application in the ABOVENORMAL priority class  BELOWNORMAL Start application in the BELOWNORMAL priority class  NODE        Specifies the preferred Non-Uniform Memory Architecture  NUMA              node as a decimal integer  AFFINITY    Specifies the processor affinity mask as a hexadecimal number              The process is restricted to running on these processors               The affinity mask is interpreted differently when  AFFINITY and              NODE are combined   Specify the affinity mask as if the NUMA             node s processor mask is right shifted to begin at bit zero              The process is restricted to running on those processors in             common between the specified affinity mask and the NUMA node              If no processors are in common  the process is restricted to             running on the specified NUMA node  WAIT        Start application and wait for it to terminate

User · Answer

There is a useful difference between call and start  wait when calling regsvr32 exe  s for example  also referenced by Gary in  in his answer to how-do-i-get-the-application-exit-code-from-a-windows-command-line  call regsvr32 exe  s broken dll echo  errorlevel    will always return 0 but  start  wait regsvr32 exe  s broken dll echo  errorlevel    will return the error level from regsvr32 exe

User · Answer

Call  Calls one batch program from another without stopping the parent batch program  The call command accepts labels as the target of the call  Call has no effect at the command-line when used outside of a script or batch file  https   technet microsoft com en-us library bb490873 aspx  Start  Starts a separate Command Prompt window to run a specified program or command  Used without parameters  start opens a second command prompt window  https   technet microsoft com en-us library bb491005 aspx

[windows] CALL command vs. START with /WAIT option

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