CMD error filename/directory error - windows

Question

I used to program batch files for work but I quit since a long time, now I'm back on the job and there seemed to be a bit of a problem.
I try to edit txt files using CMD commands on a batch file:
e.g. echo hello >> *.txt
the thing is I want to add the text to all the txt files in that directory and I remember the * represented all the files in that directory with the same extension unless it's used as *.* then it includes all the files, but now all it does is just writes this error on cmd:
The filename, directory name, or volume label syntax is incorrect.
Can anyone can give a little help?

Answer 1

You can use a FOR /F loop with a DIR command to iterate the full paths and pass those over to the redirection append >> to echo to the text files accordingly.
Example FOR Loop
Be sure to change the value of the Folder= variable to be the directory you need to append to the files with the ECHO command.
Confirmed working batch script example
#ECHO ON
SET Folder=C:\MyFolder
CD /D "%Folder%"
FOR /F "TOKENS=*" %%A IN ('DIR /B /A-D "%Folder%\*.txt"') DO ECHO HELLO>>%%~fA
PAUSE
EXIT
Further Resources
DIR
FOR /F
In addition, substitution of FOR variable references has been
enhanced. You can now use the following optional syntax:
%~I - expands %I removing any surrounding quotes (")
%~fI - expands %I to a fully qualified path name
%~dI - expands %I to a drive letter only
%~pI - expands %I to a path only
%~nI - expands %I to a file name only
%~xI - expands %I to a file extension only
%~sI - expanded path contains short names only
%~aI - expands %I to file attributes of file
%~tI - expands %I to date/time of file
%~zI - expands %I to size of file
%~$PATH:I - searches the directories listed in the PATH
environment variable and expands %I to the
fully qualified name of the first one found.
If the environment variable name is not
defined or the file is not found by the
search, then this modifier expands to the
empty string