batch file help: parentheses

yky378 · 06 Dec 2021

I have the following batch commands to extract and compare the last character of strings in a file:

@for /f "tokens=1 delims=;" %%A in ( C:\test.txt) do set d=%%A
@echo %d%
@echo %d:~-1%
@set c=%d:~-1%
@echo %c%
@if %c%==m @echo found it

It works as I hoped but only for the last line in the file test.txt. I'd like to have the batch commands work on every line in the file test.txt. So, I put commands after the "do' command in parentheses. Now, nothing works. I got an error message saying "@echo was unexpected at this time."

My guess is one of the variable is now empty. So, I add before the "For" command "setlocal EnableDelayedExpansion." It did not help and I don't know what triggers the error message.

Wobitancrawfodi · 07 Dec 2021

Can you post a sample of the file you are processing, please.

Try3 · 07 Dec 2021

You are not using the For command correctly.
- You have told it to work its way through setting each line to be the value of the variable d
- It is doing exactly what you have told it to do.
- It works through every line setting each one as d in turn until it finally arrives at the last line and sets it as d
- Only then does it move on to the next command line @echo %d% so you only get to see its last action.

In order to achieve what I think you want to achieve, you should use the For command to call a subroutine and do your processing within that.
- Using subroutines can be thought of as an alternative to using EnableDelayedExpansion. I find subroutines much easier to write, understand & debug.

Code:

for /f "tokens=1 delims=;" %%A in ( C:\test.txt) do Call :Processing "%%A"
Pause at the end of it all
:: This is where you would move on to do whatever it is that you want to do next.
Exit

:Processing
Set "ThisLine=%~1"
echo "%ThisLine%"
echo "%ThisLine:~-1%"
set "c=%:ThisLine~-1%"
echo "%c%"
if "%c%==m" echo found it
Pause in each iteration of the For command
GoTo :EOF

- Variables need to be wrapped in " unless & until you check that they contain no special characters such as ampersands.
- Variables need to be wrapped in " if they contain spaces.
- If there are no spaces or special characters you can remove the " from "%%A" & the subroutine.

I do not know why you are limiting the For command with "tokens=1 delims=;" but that's up to you.

To see For's built-in Help, enter this command

Code:

For /?

For - SS64
For - Looping commands - SS64
For -F - SS64 Forum

All the best,
Denis

yky378 · 08 Jan 2022

Thanks for the help. I got the batch file to work. Here it is:

Code:

REM This script first deletes the file C:DELETE-ALL-4-NEW.txt, if it exists
REM It then proceeds to read from C:\DELETE-ALL-NEW.txt line by line and
REM delete the file in those lines from several disks.
REM If the line contains not a file but a directory, as the line ending with a "\",
REM the script will skip it. 
REM 2021/12/08


@echo off

if exist C:\DELETE-all-4-NEW.txt DEL /Q C:\DELETE-all-4-NEW.txt
(for /f "tokens=1 delims=;" %%A in ( C:\DELETE-all-NEW.txt) do (

set "d=%%A"
    setlocal enabledelayedexpansion
    echo !d!
    echo !d:~-1!
    set "c=!d:~-1!"
    echo %c%
    if /I not "!c!"=="\"  DEL /Q /A "D:\%%A" & DEL /Q /A "E:\%%A" & DEL /Q /A "F:\%%A"

endlocal
) >> C:\DELETE-all-4-NEW.txt 2>&1
)
CD /D C:\

Try3 · 08 Jan 2022

I'm glad it works now.

By the way, it's up to you but
- REM is quite slow.
- Like many people I only use REM if I deliberately want those lines to appear onscreen whenever the batch file runs.
- Like many people, I use :: otherwise. It's a bit of a trick in that it makes Windows treat it as an inoperative line but one that it does not take the time to bother displaying or even reading fully.
- There was an example of its use for remarks in my last post as well.
- The last time I put the REM / :: comparison to the test was about thirty years ago and, on that occasion, it reduced the running time for a batch file containing a hundred or more REMs from 30 secs to 1 or 2 secs. So it's not vital for normal batch files.

Code:

:: This script first deletes the file C:DELETE-ALL-4-NEW.txt, if it exists
:: It then proceeds to read from C:\DELETE-ALL-NEW.txt line by line and
:: delete the file in those lines from several disks.
:: If the line contains not a file but a directory, as the line ending with a "\",
:: the script will skip it. 
:: 2021/12/08

All the best,
Denis