Windows CMD batch file frequent issues/tips

windows-cmd-faq.md

Writing Windows CMD Batch File Stuff

I hope I never have to write another Windows .BAT file again in my life, but if I don't jot this stuff down, I will forget it, and then I will.

Subroutines

1. Use :somelabel to define a block of code.
2. Use call :somelabel to jump to a defined label, run that block of code to the end, then return.
3. Use goto :label to jump to that label.
4. Put :eof at the end of your file.

So,

if (some error) do (
echo nope, you messed up
goto :eof
)

for (whatever) do (
call :myprocess
)
goto :eof

:myprocess
echo do stuff here
:eof

Looping over an input file

https://stackoverflow.com/questions/10653371/how-do-i-get-a-batch-file-to-accept-input-from-a-txt-file

for /f %%a in (a-file-with-one-thing-per-line.txt) do (
echo Here's the line: %%a
)

Get the filename out of a URL

https://stackoverflow.com/questions/9252980/how-to-split-the-filename-from-a-full-path-in-batch

"if not exist"

https://stackoverflow.com/questions/23735282/if-not-exist-command-in-batch-file

I used this to determine if a program was installed (I'm sure there's some better wiz-bang way to check the registry for it...)

:: Check if chrome is in the right place
if not exist "C:\Program Files (x86)\Google\Chrome\Application\chrome.exe" (
echo You don't have Chrome installed in "C:\Program Files (x86)\Google\Chrome\Application\chrome.exe".
goto :eof
)

Number of command-line arguments

https://stackoverflow.com/questions/1291941/batch-files-number-of-command-line-arguments

There's not something like $# in bash, so there's a whole level of hell involving looping and/or a bunch of GOTOs.

I wanted to check if there were no arguments; you can do this:

if "%1"=="" (
echo You need to pass at least one parameter, sorry.
goto :eof
)

Slashes to dashes

rem change slashes to dashes in the first parameter passed
SET _test=%1
SET _result=%_result:/=-%

That second line is replacing one string with another, so you can do stuff like this, too:

SET _result=%_result:pepsi=coke%

For lots more of this https://www.dostips.com/DtTipsStringManipulation.php

Related: https://gist.github.com/jkonrath/fb471f4d15947555af254c877ca04d53

Make a timestamped file

I covered this over here: https://gist.github.com/jkonrath/25188b7d8d59cd55b5843e0e557c06c6

Disclaimer

I have no idea what I'm doing. I learned all of this by brute force. It worked for me, but it might not work for you, and it's probably not the best way of doing things.

Also I just realized I don't even have a machine to test these anymore, so caveat emptor.