Use o comando FOR para fazer um loop sobre cada arquivo de lote filho.
FOR %%B IN sub*.bat DO CALL %%B
For - Loop through files - Windows CMD - SS64
Conditionally perform a command on several files.
Syntax FOR %%parameter IN (set) DO command Key set : A set of one or more files, separated by any standard delimiter. Wildcards can be used. command : The command to carry out, including any command-line parameters. %%parameter : A replaceable parameter: e.g. in a batch file use %%G (on the command line %G)
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Although wildcards can be used, an alternative method of processing files is to let FOR /F process the output of the command 'DIR /b' This can be useful when you want to use DIR options like sorting.