Batch script loop

Question

I need to execute a command 100-200 times, and so far my research indicates that I would either have to copy/paste 100 copies of this command, OR use a for loop, but the for loop expects a list of items, hence I would need 200 files to operate on, or a list of 200 items, defeating the point.

I would rather not have to write a C program and go through the length of documenting why I had to write another program to execute my program for test purposes. Modification of my program itself is also not an option.

So, given a command, a, how would I execute it N times via a batch script?

Note: I don't want an infinite loop

For example, here is what it would look like in Javascript:

var i;
for (i = 0; i < 100; i++) {
  console.log( i );
} 

What would it look like in a batch script running on Windows?

Answer 1

for /l is your friend:

for /l %x in (1, 1, 100) do echo %x

Starts at 1, steps by one, and finishes at 100.

Use two %s if it's in a batch file

for /l %%x in (1, 1, 100) do echo %%x

(which is one of the things I really really hate about windows scripting)

If you have multiple commands for each iteration of the loop, do this:

for /l %x in (1, 1, 100) do (
   echo %x
   copy %x.txt z:\whatever\etc
)

or in a batch file

for /l %%x in (1, 1, 100) do (
   echo %%x
   copy %%x.txt z:\whatever\etc
)

Key:
/l denotes that the for command will operate in a numerical fashion, rather than operating on a set of files
%x is the loops variable
(starting value, increment of value, end condition[inclusive] )

Answer 2

And to iterate on the files of a directory:

@echo off 
setlocal enableDelayedExpansion 

set MYDIR=C:\something
for /F %%x in ('dir /B/D %MYDIR%') do (
  set FILENAME=%MYDIR%\%%x\log\IL_ERROR.log
  echo ===========================  Search in !FILENAME! ===========================
  c:\utils\grep motiv !FILENAME!
)

You must use "enableDelayedExpansion" and !FILENAME! instead of $FILENAME$. In the second case, DOS will interpret the variable only once (before it enters the loop) and not each time the program loops.

Answer 3

Template for a simple but counted loop:

set loopcount=[Number of times]
:loop
[Commands you want to repeat]
set /a loopcount=loopcount-1
if %loopcount%==0 goto exitloop
goto loop
:exitloop

Example: Say "Hello World!" 5 times:

@echo off
set loopcount=5
:loop
echo Hello World!
set /a loopcount=loopcount-1
if %loopcount%==0 goto exitloop
goto loop
:exitloop
pause

This example will output:

Hello World!
Hello World!
Hello World!
Hello World!
Hello World!
Press any key to continue . . .

Answer 4

You could also try this instead of a for loop:

set count=0
:loop
set /a count=%count%+1
(Commands here)
if %count% neq 100 goto loop
(Commands after loop)

It's quite small and it's what I use all the time.

Answer 5

You could do something to the following effect avoiding the FOR loop.

set counter=0
:loop
echo "input commands here"
SET /A counter=%counter%+1
if %counter% GTR 200
(GOTO exit) else (GOTO loop)
:exit
exit

Answer 6

Or you can decrement/increment a variable by the number of times you want to loop:

SETLOCAL ENABLEDELAYEDEXPANSION
SET counter=200
:Beginning
IF %counter% NEQ 0 (
echo %x
copy %x.txt z:\whatever\etc
SET /A counter=%counter%-1
GOTO Beginning
) ELSE (
ENDLOCAL
SET counter=
GOTO:eof

Obviously, using FOR /L is the highway and this is the backstreet that takes longer, but it gets to the same destination.

Answer 7

You can do this without a for statement ^.^:

@echo off
:SPINNER
SET COUNTP1=1

:1
CLS
 :: YOUR COMMAND GOES HERE
IF !COUNTP1! EQU 200 goto 2

SET COUNTP1=1
) ELSE (
SET /A COUNTP1+=1
)
goto 1

:2
:: COMMAND HAS FINISHED RUNNING 200 TIMES

It has basic understanding. Just give it a test. :P

Answer 8

Very basic way to implement looping in cmd programming using labels

@echo off
SET /A "index=1"
SET /A "count=5"
:while
if %index% leq %count% (
   echo The value of index is %index%
   SET /A "index=index + 1"
   goto :while
)

Answer 9

DOS doesn't offer very elegant mechanisms for this, but I think you can still code a loop for 100 or 200 iterations with reasonable effort. While there's not a numeric for loop, you can use a character string as a "loop variable."

Code the loop using GOTO, and for each iteration use SET X=%X%@ to add yet another @ sign to an environment variable X; and to exit the loop, compare the value of X with a string of 100 (or 200) @ signs.

I never said this was elegant, but it should work!

Answer 10

Not sure if an answer like this has already been submitted yet, but you could try something like this:

@echo off
:start
set /a var+=1
if %var% EQU 100 goto end
:: Code you want to run goes here
goto start

:end
echo var has reached %var%.
pause
exit

The variable %var% will increase by one until it reaches 100 where the program then outputs that it has finished executing. Again, not sure if this has been submitted or something like it, but I think it may be the most compact.

Answer 11

I use this. It is just about the same thing as the others, but it is just another way to write it.

@ECHO off
set count=0
:Loop
if %count%==[how many times to loop] goto end
::[Commands to execute here]
set count=%count%+1
goto Loop
:end

Answer 12

The answer really depends on how familiar you are with batch, if you are not so experienced, I would recommend incrementing a loop variable:

@echo off
set /a loop=1
:repeat
echo Hello World!
set /a loop=%loop%+1
if %loop%==<no. of times to repeat> (
goto escapedfromrepeat
)
goto repeat
:escapedfromrepeat
echo You have come out of the loop
pause

But if you are more experienced with batch, I would recommend the more practical for /l %loop in (1, 1, 10) do echo %loop is the better choice.

             (start at 1, go up in 1's, end at 10)
for /l %[your choice] (start, step, end) do [command of your choice]

Answer 13

Here is a template script I will use.

@echo off
goto Loop

:Loop
<EXTRA SCRIPTING HERE!!!!>
goto Loop

exit

What this does is when it starts it turns off echo then after that it runs the "Loop" but in that place it keeps going to "Loop" (I hope this helps.)

Answer 14

a completely flawless loop

set num=0
:loop
:: insert code
set num=%num%+1
if %num% neq 10 goto loop
::insert after code code

you can edit it by changing the 10 in line 5 to any number to represent how many time you want it to loop.

Answer 15

(EDITED) I made it so it stops after 100 times

@echo off
goto actual
set /a loopcount=0
:actual
set /a loopcount=%loopcount% + 1
echo %random% %random% %random% %random%
timeout 1 /nobreak>nul
if %loopcount%== 100 goto stop
goto actual
:stop
exit

This will generate 4 random numbers ever 1 second 100 times. Take out the "timeout 1 /nobreak>nul" to make it go super fast.

Answer 16

I have 2 answers Methods 1: Insert Javascript into Batch

@if (@a==@b) @end /*

:: batch portion

@ECHO OFF

cscript /e:jscript "%~f0"


:: JScript portion */

Input Javascript here

( I don't know much about JavaScript )

Method 2: Loop in Batch

   @echo off
    set loopcount=5
    :loop
    echo Hello World!
    set /a loopcount=loopcount-1
    if %loopcount%==0 goto exitloop
    goto loop
    :exitloop
    pause

(Thanks FluorescentGreen5)