command line - Renaming dates under windows cmd

I have a bunch of directories (folders, if you like) that follow this pattern

\20121022 Description of the directory's contents goes here\  

(some don't have it, just the date)

and I need to rename them to follow the following pattern

\2012-10-22 Description of the directory's contents ...\

Is there a way to do it using Windows cmd and the tools that come with it (namely, ren)? If not, what would be the most portable way to do it? I have a very restricted set of privileges on the machine I'm doing this on.

Answer

If you start with the directory name in a variable, like fdir:

set "fdir=20121022 Description of this directory"

Then your batch file can split up the directory name:

set "fdiryear=%fdir:~0,4%"
set "fdirmonth=%fdir:~4,2%"
set "fdirday=%fdir:~6,2%"
set "fdirdesc=%fdir:~8%"

at this point, the variables look like:

fdir=20121022 Description of this directory
fdiryear=2012
fdirmonth=10
fdirday=22
fdirdesc= Description of this directory

Then define the new directory name, and rename the directory:

set "fnew=%fdiryear%-%fdirmonth%-%fdirday%%fdirdesc%"
ren "%fdir%" "%fnew%"

the new directory name will be:

fnew=2012-10-22 Description of this directory

If you can give me some more information about how you want to collect the list of directory names, I can provide a more complete script.

For example, if all the directories are in the current directory, then the batch file would look like this:

@echo off

echo.
for /D %%f in ("2010*", "2011*", "2012*") do call :work "%%~f"

echo.
set "fdir="
set "fdiryear="
set "fdirmonth="
set "fdirday="
set "fdirdesc="
goto :EOF


:work

set fdir=%~1
set "fdiryear=%fdir:~0,4%"
set "fdirmonth=%fdir:~4,2%"
set "fdirday=%fdir:~6,2%"
set "fdirdesc=%fdir:~8%"

set "fnew=%fdiryear%-%fdirmonth%-%fdirday%%fdirdesc%"
echo Renaming folder "%fdir%" to "%fnew%"
rem    ren "%fdir%" "%fnew%"
goto :EOF

Explanations:

This will turn off the echoing of the commands as they are executed to avoid a lot of clutter on the screen:

@echo off

This will display a blank line:

echo.

The for command:

for /D %%f in ("2010*", "2011*", "2012*") do call :work "%%~f"

/D means to search for matches of Directory names only.
If you omit the /D, it will search for matches of Filenames only.


%%f (%%~f) is a variable name that gets set to the names of the matched directories.

[in ("2010*", "2011*", "2012*")] is a list of patterns to search for. 
In this case, it will only process directories that begin with a year: 
2010, or 2011, or 2012. You can edit this list for your needs. If you 
know that all directories in the current folder are in the same format 
and are candidates to be renamed, the list can be simply: ("*") like:  
for /D %%f in ("*") do call :work "%%~f"


the word "do" simply precedes the command that you want to "do" for each 
match found.

call :work says to execute the commands at the label :work for each match.

"%%~f" says to pass the matched directory name as the first argument to the 
commands at the label you specified (:work)  

The "~" in "%%~f" says to remove "quote" marks from %%f to avoid passing the 
directory name inside of 2 sets of "quote" marks. For example, if %%f contained 

"20121022 Description of this directory" then using "%%f" would pass 
""20121022 Description of this directory"", which would fail. "%%~f" will pass 
exactly 1 set of "quotes".

After all the matching directory names are processed, execution returns to the "echo." command that follows the "for ..." command.

Next is just some "cleanup" to clear the variables used in the script so they don't accumulate and clutter up the variable space (environment).

set "fdir="

set "fdiryear="
set "fdirmonth="
set "fdirday="
set "fdirdesc="

The next statement exits the batch script and ends execution.

goto :EOF

Next is the label

:work

Labels begin with a colon at the first column followed by a 
label name made up of letters and numbers (no spaces). Labels are 
the targets of call and goto commands.  

Then the command:

set fdir=%~1

Sets the variable named "fdir" to be the directory name that was 
passed from the "for" command.

The "~" in %~1 means to use the name only without any surrounding "quote" marks.

The next commands:

set "fdiryear=%fdir:~0,4%"
set "fdirmonth=%fdir:~4,2%"
set "fdirday=%fdir:~6,2%"
set "fdirdesc=%fdir:~8%"
set "fnew=%fdiryear%-%fdirmonth%-%fdirday%%fdirdesc%"

Split up the directory name into the desired pieces, and 
define the "new" directory name.

The next command:

echo Renaming folder "%fdir%" to "%fnew%"

Just displays the old and new directory names so you can see the 
progress on the screen.

And the last commands:

rem    ren "%fdir%" "%fnew%"
goto :EOF

Renames the directory and then "exits" to return from the call.

Note: I made the actual command to rename the directory a comment so you can run the batch file and see what will happen without actually renaming anything. Once you have run it and are confident the correct directories will be properly renamed, you can edit the line to rename the directory and run the batch script again.

To do that, remove the "rem" from the line so:

rem    ren "%fdir%" "%fnew%"

Becomes:

ren "%fdir%" "%fnew%"