Best way to check if directory is writable in BAT script?

Question

How can I check whether a directory is writable by the executing user from a batch script?

Here's what I've tried so far:

> cd "%PROGRAMFILES%"

> echo. > foo
Access is denied.
> echo %ERRORLEVEL%
0

Ok, so how about...

> copy NUL > foo
Access is denied.
> echo %ERRORLEVEL%
0

Not that either? Then what about...

> copy foo bar
Access is denied.
        0 file(s) copied.
> echo %ERRORLEVEL%
1

This works, but it breaks if the file doesn't exist.

I've read something about internal commands not setting ERRORLEVEL, but copy obviously seems to do so in the last case.

Answer 1

Definitely running a command against it to find if its denied is the easy way to do it. You can also use CACLS to find exactly what the permissions are or aren't. Here's a sample.

In CMD type CACLS /?

CACLS "filename" will give you what the current permissions is allowed on the file. R = Read, W = Write, C = Change (same as write?), F = Full access.

EDIT: You can use directory name as well.

So to do a check, you would:

FOR /F "USEBACKQ tokens=2 delims=:" %%F IN (`CACLS "filename" ^| FIND "%username%"`) DO (
 IF "%%F"=="W" (SET value=true && GOTO:NEXT)
 IF "%%F"=="F" (SET value=true && GOTO:NEXT)
 IF "%%F"=="C" (SET value=true && GOTO:NEXT)
 SET value=false
)
ECHO This user does not have permissions to write to file.
GOTO:EOF
:NEXT
ECHO This user is able to write to file.

Answer 2

You can write copy %0 foo to copy the batch file itself.
This will always exist.

Remember to delete the file afterwards, and to make sure that you aren't overwriting an existing file by that name.

There ought to be a better way to do this, but I don't know of any.

EDIT: Better yet, try mkdir foo.
In case the batch file is running off a network (or if it's very large), this may be faster.