How to add a prefix to all files and folders in a folder? (windows)

Question

The following command only changes the name of the files but not the folders.

for %a in (*) do ren "%a" "00_%a"

Answer 1

The following command only changes the name of the files but not the folders.

for %a in (*) do ren "%a" "00_%a"

Notes:

• Using for as above is not advised.
• There is a possibility that files can be renamed multiple times.
• See below for the reason why.

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Use the following in a cmd shell:

for /f "tokens=*" %a in ('dir /b') do ren "%a" "00_%a"

In a batch file (replace % with %%):

for /f "tokens=*" %%a in ('dir /b') do ren "%%a" "00_%%a"

Note:

It is critical that you use FOR /F and not the simple FOR.

The FOR /F gathers the entire result of the DIR command before it begins iterating, whereas the simple FOR begins iterating after the internal buffer is full, which adds a risk of renaming the same file multiple times.

as advised by dbenham in his answer to add "text" to end of multiple filenames:

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Further Reading

• An A-Z Index of the Windows CMD command line - An excellent reference for all things Windows cmd line related.
• dir - Display a list of files and subfolders.
• for /f - Loop command against the results of another command.

Answer 2

To perform this For loop on folders (directories) instead of files, simply include the /D switch.

for /D %a in (*) do ren "%a" "00_%a"

From for /?:

FOR /D %variable IN (set) DO command [command-parameters]

If set contains wildcards, then specifies to match against directory
names instead of file names.