Sorting numerically in a comma-delimited file with Unix

I've got a comma-separated file that looks like this:

100,00869184
6492,8361
1234,31
200,04071

I want to use sort to sort this file numerically by the first column only.

Desired Result:

100,00869184
200,04071
1234,31
6492,8361

How do I achieve this using sort? It seems like the commas are being treated like thousands separators instead of delimiters even when I call them out as such.

Both sort -t',' -n and sort -t',' -nk1' give me this:

1234,31
200,04071
6492,8361
100,00869184

Sorting by the default (no parameters) or using sort -t',' gives me this:

100,00869184
1234,31
200,04071
6492,8361

And sorting as a number sort -n gives me this:

1234,31
200,04071
6492,8361
100,00869184

How can I use sort to achieve my desired result?

Edited to add: This is for a one-time operation to create a sorted list of about 7 million lines, so workarounds or other unorthodox methods are perfectly acceptable.

This is certainly a dirty workaround, but I figured out a way to do this thanks to @slhck's tip about locales. If a better answer comes along that would be more helpful to others, I'll certainly accept it since this pretty much only works for my specific problem.

I set the locale to Spanish (Bolivian) so that the commas were treated like decimal points, then standard numeric sorting did the trick.

$ export LC_NUMERIC="es_BO.utf8"

$ cat test.csv
100,00869184
6492,8361
1234,31
200,04071

$ sort -n test.csv
100,00869184
200,04071
1234,31
6492,8361

GNU's sort does this by default:

$ cat test
100,00869184
6492,8361
1234,31
200,04071

$ gsort -nt',' < test
100,00869184
200,04071
1234,31
6492,8361

Version:

$ gsort --version
sort (GNU coreutils) 8.19

There's a caveat though: If your sorting does not work as expected, then your locale is probably set to something different than C. Why is this? locale defines sorting and interpretation of letters, numbers, decimal characters et cetera.

To check this, just enter locale in a Terminal. Is LC_NUMERIC set to en_US.UTF-8, maybe? This would explain the wrong sort order. Set it back to C:

export LC_NUMERIC=C

Then, try your sort command again. If you want to set your global locale to C, do this with:

export LC_ALL=C

Try adding the -g option which is suppose to perform numeric sorting.

Try:

sort -t',' -g <whatever>