If a file exists,
> will overwrite the file and
>> will append to the end of the file. If a file does not exist, both will create a new file.
echo command automatically adds a newline after your string.
echo 1 > num.txt echo 1 > num.txt echo 2 >> num.txt
will create the following file:
1 1 2
Furthermore, you cannot just modify a single line in a text file. You have to read the whole file, modify it in your code and then write to the whole file again.
[command] [> | >>] [filename]
> saves the output of [command] into [filename].
>> appends the output of [command] into [filename].
echo Hello World > myfile.txt saves "Hello World" into myfile.txt
echo your name is %name% >> myfile.txt appends "your name is xxxx" into myfile.txt
dir C:\ > directory.txt saves the directory of C:\ to directory.txt
Ways to create a file with the echo command:
ECHO. > example.bat (creates an empty file called "example.bat") ECHO message > example.bat (creates example.bat containing "message") ECHO message >> example.bat (adds "message" to a new line in example.bat) (ECHO message) >> example.bat (same as above, just another way to write it)
If you want to create a file via the
ECHO command, in a specific directory on your computer, you might run into a problem.
ECHO Hello how are you? > C:\Program Files\example.bat (This will NOT make a file in the folder "Program Files", and might show an error message)
But then how do we do it? Well it's actually extremely simple... When typing a path or file name that has a space included in it's name, then remember to use "quotes"
ECHO Hello how are you? > "C:\Program Files\example.bat" (This will create "example.bat" in the folder "Program Files")
But what if you want to make a file that outputs a new file?
ECHO message > file1.bat > example.bat (example.bat is NOT going to contain "message > file1.bat") example.bat will just contain "message"... nothing else
Then how do we do this? Well for this we use the
ECHO message ^> file1.bat > example.bat (example.bat is going to contain "message > file1.bat")
Same goes for other stuff in batch
The next step requires you to have some knowledge about variables and statements:
SET example="text" ECHO %example% > file.bat (This will output "text" to file.bat)
if we don't want it to output "text" but just plain %example% then write:
ECHO ^%example^% > file.bat (This will output "%example%" to file.bat)
ELSE statements are written with "pipes" || IF ^%example^%=="Hello" ECHO True || ECHO False > file.bat (example.bat is going to contain "if %example%=="Hello" echo True") [it ignores everything after the ELSE statement]
to output the whole line then we do the same as before.
IF ^%example^%=="Hello" ECHO True ^|^| ECHO False > file.bat This will output: IF %example%=="Hello" ECHO True || ECHO False
If the variable is equal to "Hello" then it will say "True", ELSE it will say "False"
ECHO commands to create a batch file:
( echo echo hi, this is the date today echo date /T echo echo created on %DATE% echo pause >nul )>hi.bat
The command interpreter treats the whole section in parenthesis as a single command, then saves all the output to
hi.bat now contains:
echo hi, this is the date today date /T echo created on [date created] pause >nul