What are these lines of batch code for?
batch-file, cmd, command-line, shell, windows
Solution
In short, the code[1] :
creates a temporary `desktop.txt` file whose content will eventually become `desktop.ini`, but with a different encoding.
the commands in question then convert the current-console-codepage-encoded file `desktop.txt` (e.g., on an en-US system, `CP-437`) to `UTF-16 LE`-encoded file `desktop.ini`, which is the (culture-independent) file File Explorer uses to control display of the folder at hand.
sets the `system` (`+S`) and `hidden` (`+H`) attributes for both the `desktop.ini` file and the associated icon file, `image.ico`, because that's how these files should be marked (given that they only control display of the containing folder, and aren't data files themselves).
Specifically, the 3 lines of interest do the following:
`CHCP 1252 >NUL` (silently) changes to the Windows-1252 code page.
`CMD.EXE /D /A /C (SET/P=ÿþ)<NUL > desktop.ini 2>NUL` effectively sends string `ÿþ` to output file `desktop.ini` - `ÿþ`, when interpreted as a `Windows-1252`-encoded string, amounts to bytes `0xFF 0xFE`, which is the BOM (byte-order mark) used to identify `UTF-16 LE`-encoded files; in other words: sending this string to file `desktop.ini` marks it as an `UTF-16 LE`-encoded file.
- `/D` simply suppresses any auto-run functionality that may be defined via the registry
- `/A` tells `cmd.exe` to output "ANSI"-encoded strings, where "ANSI" refers to the default codepage - which is now set to `Windows-1252`
- `/C` means that the following arguments should be executed as a command, and that `cmd.exe` should exit after the command terminates.
`CMD.EXE /D /U /C TYPE desktop.txt >> desktop.ini` then appends the contents of the previously created `desktop.txt` file to `desktop.ini`, using "Unicode" (`UTF-16 LE`) encoding (thanks to `/U`), which completes the conversion of temporary file `desktop.txt` to `UTF-16 LE`-encoded `desktop.ini` (after which `desktop.txt` is removed).
[1] This answer interprets the code's intent, which doesn't mean that it necessarily works, especially in Windows 10; for instance, interactively assigning an icon seems to set a different, single property that combines the image file and the index of its specific internal resource: e.g., `IconResource=C:\Users\jdoe\Desktop\image.ico,0`
As for the need to create `UTF-16 LE`-encoded files: it's not a strict requirement - apparently, Windows itself, when you use File Explorer to assign an icon, creates files in the current legacy - single-byte - encoding (e.g., `Windows-1252`). That said, using a culture-independent encoding such as `UTF-16 LE` is at least in principle the most robust approach. However, if all the values you're writing to `desktop.ini` are ASCII-only characters (7-bit range), it's safe to simply pipe `echo` output to `desktop.ini` directly.
At the end of the day, using a batch file to determine folder display attributes is a fragile approach, given that it is essentially based on reverse-engineering the official APIs - which may change.
More generally, using batch files to do anything is best avoided these days - use PowerShell instead.
Problem
I came across the following batch code on SuperUser, the purpose of which is to programmatically replace a folder's icon. ``` CD "%userprofile%\desktop" MKDIR "TEST FOLDER" ATTRIB +s "TEST FOLDER" CD "TEST FOLDER" COPY /Y "%userprofile%\desktop\image.ico" "./image.ico" ECHO [.ShellClassInfo] >> desktop.txt ECHO ConfirmFileOp=0 >> desktop.txt ECHO NoSharing=1 >> desktop.txt ECHO IconFile=image.ico >> desktop.txt ECHO IconIndex=0 >> desktop.txt ECHO InfoTip= >> desktop.txt CHCP 1252 >NUL CMD.EXE /D /A /C (SET/P=ÿþ)<NUL > desktop.ini 2>NUL CMD.EXE /D /U /C TYPE desktop.txt >> desktop.ini DEL /F /Q desktop.txt ATTRIB +S +H desktop.ini image.ico ``` I get the rest of the script easily enough, but I'm having trouble understanding these three lines: ``` CHCP 1252 >NUL CMD.EXE /D /A /C (SET/P=ÿþ)<NUL > desktop.ini 2>NUL CMD.EXE /D /U /C TYPE desktop.txt >> desktop.ini ``` SS64 tells me `chcp 1252` is related to something called a "code page", 1252 corresponding to "West European Latin", so my best guess is that this forces the script to use a Latin character set. The second two lines open instances of CMD; SS64 says the /A switch on the first makes it output in ANSI while the /U on the second makes it output Unicode. That's about as much as I can speculate on, and I'd really appreciate it if someone could go through each major part of these three lines and tell me what they're doing. Thanks!