Conditionally perform a command several times.
syntax-FOR-Files FOR %%parameter IN (set) DO command syntax-FOR-Files-Rooted at Path FOR /R [[drive:]path] %%parameter IN (set) DO command syntax-FOR-Folders FOR /D %%parameter IN (folder_set) DO command syntax-FOR-List of numbers FOR /L %%parameter IN (start,step,end) DO command syntax-FOR-File contents FOR /F ["options"] %%parameter IN (filenameset) DO command FOR /F ["options"] %%parameter IN ("Text string to process") DO command syntax-FOR-Command Results FOR /F ["options"] %%parameter IN ('command to process') DO command
The operation of the FOR command can be summarised as...
If you are using the FOR command at the command line rather than in a batch program, use just one percent sign: %G instead of %%G.
The first parameter has to be defined using a single character, for example the letter G.
FOR %%G IN ...
In each iteration of a FOR loop, the IN ( ....) clause is evaluated and %%G set to a different value
If this clause results in a single value then %%G is set equal to that value and the command is performed.
If the clause results in a multiple values then extra parameters are implicitly defined to hold each. These are automatically assigned in alphabetical order %%H %%I %%J ...(implicit parameter definition)
If the parameter refers to a file, then enhanced variable reference may be used to extract the filename/path/date/size.
You can of course pick any letter of the alphabet other than %%G.
%%G is a good choice because it does not conflict with any of the pathname format letters (a, d, f, n, p, s, t, x) and provides the longest run of non-conflicting letters for use as implicit parameters.
G > H > I > J > K > L > M
Format letters are case sensitive, so using a capital letter is also a good way to avoid conflicts %%A rather than %%a.
FOR /F "tokens=1-5" %%A IN ("This is a short sentence") DO @echo %%A %%B %%D
will result in the output: This is short
Create a set of 26 folders, one for each letter of the alphabet:
FOR %%G IN (a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z) DO (md C:\demo\%%G)
Running multiple commands in a FOR loop
Within a FOR loop, variables are expanded at the start of the loop and don’t update until the entire DO section has completed.
The following example counts the files in the current folder, but %count% always returns 1:
FOR /f "tokens=*" %%G IN ('dir /b') DO (
set /a count+=1 )
To update variables within each iteration of the loop we must either use EnableDelayedExpansion or else use the CALL :subroutine mechanism as shown below:
FOR /f "tokens=*" %%G IN ('dir /b') DO (call :subroutine "%%G")
set /a count+=1
Nested FOR commands
FOR commands can be nested FOR %%G... DO (for %%U... do ...)
when nesting commands choose a different letter for each part. you can then refer to both parameters in the final DO command.
If Command Extensions are disabled, the FOR command will only support the basic syntax with no enhanced variables:
FOR %%parameter IN (set) DO command [command-parameters]
FOR is an internal command.
“Those who cannot remember the past are condemned to repeat it” - George Santayana
FOR - Loop through a set of files in one folder
FOR /R - Loop through files (recurse subfolders)
FOR /D - Loop through several folders
FOR /L - Loop through a range of numbers
FOR /F - Loop through items in a text file
FOR /F - Loop through the output of a command
Parameters/arguments %~ options
FORFILES - Batch process multiple files
GOTO - Direct a batch program to jump to a labelled line
IF - Conditionally perform a command
Powershell: ForEach-Object - Loop for each object in the pipeline
Equivalent bash command (Linux): for var in [list]; do - Expand list, and execute commands