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, specify %parameter instead of %%parameter.
The FOR command supports implicit parameter definitions.
The first parameter always has to be defined explicitly and this must be a single character.
e.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 results in a single value then %%G is set = to that value and the command is performed.
If this results in a multiple values then extra parameters are implicitly defined to hold each. These are automatically assigned in alphabetical order %%H %%I %%J ...
FOR /F %%G IN ("This is a long sentence") DO @echo %%G %%H %%J
will result in the output
This is long
You can of course pick any letter of the alphabet other than
%%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
Other Environment variables
Environment variables within a FOR loop are expanded at the beginning of the loop and won't change until AFTER the end of the DO section. So in the following snippet %count% will not display the expected result:
SET count=1 FOR /f "tokens=*" %%G IN ('dir /b') DO ( echo %count%:%%G set /a count+=1)
To force the variable to be evaluated during each iteration, use the CALL :subroutine mechanism to take the evaluation outside of the FOR loop.
SET count=1 FOR /f "tokens=*" %%G IN ('dir /b') DO (call :s_do_sums %%G) GOTO :eof :s_do_sums echo %%count%%:%1 set /a count+=1 GOTO :eof
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]
"In expanding the field of knowledge, we but increase the horizon of ignorance" - Henry Miller
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
FORFILES - Batch process multiple files
GOTO - Direct a batch program to jump to a labelled line
IF - Conditionally perform a command
Equivalent Linux BASH commands:
cut - Divide a file into several columns
for var in [list]; do - Expand list, and execute commands
eval - Evaluate several commands/arguments
until - Execute commands (until error)
while - Execute commands