The problem is that you're using `%m%` inside a `for` loop. This is evaluated when the loop is read (before any iterations at all). In other words, the entire loop, up to and including the closing parenthesis, is read and evaluated before executing. So `%m%` will always be it's initial value no matter what you actually set it to within the loop.
An example should hopefully illustrate this:
set val=7
for %%i in (1) do (
set val=99
echo %val%
)
echo %val%
which results in the unexpected (to some):
7
99
simply because the `%val%` in the first echo statement is interpreted (i.e., the entire `for` loop is interpreted) before any of it is run.
You need delayed expansion along with something that will force the value of `m` to be set to the first `%%x` regardless. Using the `setlocal` command and `!m!` instead of `%m%` will delay evaluation of `m` until each time the line is executed.
In addition, setting `m` initially to nothing and forcing it to be `%%x` when it *is* nothing will ensure the first value of `%%x` is loaded into `m`.
@echo off
setlocal enableextensions enabledelayedexpansion
set m=
for /f "tokens=1,2 delims=," %%x in (my.csv) do (
if "!m!" == "" set m=%%x
if !m! lss %%x set m=%%x
)
echo Max X Value = !m!
endlocal
Using the above code with this `my.csv` file:
1,a
2,b
10,c
3,d
results in the output of:
Max X Value = 10
as expected or, for your sample data in another comment:
422,34
464,55
455,65
421,88
you get:
Max X Value = 464