w3hello.com logo
Home PHP C# C++ Android Java Javascript Python IOS SQL HTML videos Categories
Copy string of characters from the middle of filename to the beginning
@ECHO OFF
SETLOCAL
SET "sourcedir=c:folder"
FOR /f "delims=" %%a IN (
 'dir /b /a-d "%sourcedir%*" '
 ) DO (
 SET "name=%%a"
 CALL :transform
)

GOTO :EOF

:transform
ECHO REN "%sourcedir%\%name%" "%name:~13,10%%name%"
GOTO :eof

The required REN commands are merely ECHOed for testing purposes. After you've verified that the commands are correct, change ECHO REN to REN to actually rename the files.

The variable sourcedir is set to point to the directory of interest. By setting a variable, the directoryname can be changed in one place rather than editing it in multiple places should it be used in multiple places. The set "var=value" syntax ensures any trailing spaces on the line are not included in the value assigned.

The dir command produces a list of filenames in the target directory /b means "filenames only - no header/trailer lines, no date, time size - just the filename" /a-d means "and no directory names"

This list is built in memory, and then read line-by-line by the for/f. The "delims=" ensure that the entire line is applied to the metavariable %%a so that filenames that include default separators are not truncated. Each filename is then assigned to the variable name because substringing can't be applied directly to a metavariable. The subroutine :transform is then executed.

The subroutine is quite simple - all it does is echo a rename command, using the full filename built from the variables sourcedir and name. The syntax of the ren command requires that the new name is name-only, the subdirectory is implicit. The new name is built from the substring within name starting at character 13 (the first character is character 0) for a length of 10 characters + the original name.

Since the dir list is built in memory before the for starts executing, the names delivered to the for are the original names. If a file has become renamed, it will not be re-processed as its new name is not in that original list.

The idea of ECHOing the ren line is so that the user can see whether the ren commands generated are correct. All that happens is that a report is sent to the screen. If it is then determined that the result appears correct, then changing echo ren to ren will actually execute the rename rather than reporting it. That's a decision to be made by the user. If the resultant ren is wrong (wrong count of position or length, or wrong directory or whatever) then no harm is done as the product is simply a report until the job is run with echo ren changed to ren.





© Copyright 2018 w3hello.com Publishing Limited. All rights reserved.