awk loop over all fields in one file - sorting

Question

This statement gives me the count of unique values in column 1:
awk -F ',' '{print $1}' infile1.csv | sort | uniq -c | sort -nr > outfile1.csv
It does what I expected (gives the count (left) of unique values (right) in the column):
117 5
58 0
18 4
14 3
11 1
9 2
However, now I want to create a loop, so it will go through all columns.
I tried:
for i in {1..10}
do
awk -F ',' '{print $$i}' infile.csv | sort | uniq -c | sort -nr > outfile$i.csv
done
This does not do the job (it does produce a file but with much more data). I think that a variable in a print statement, as I tried with print $$i, is not something that works in general, since I did not come across it so far.
I also tried this:
awk -F ',' '{for(i=1;i<=NF;i++) infile.csv | sort | uniq -c | sort -nr}' > outfile$i.csv
But this does not give any result at all (meaning syntax errors for infile and sort command). I am sure I am using the for statement the wrong way.
Ideally, I would like the code to find the count of unique values for each column and print them all in the same output file. However, I am already very happy with a well functioning loop.
Please let me know if this explanation is not good enough, I will do my best to clarify.

Answer 1

Any time you write a loop in shell just to manipulate text you have the wrong approach. Just do it in one awk command, something like this using GNU awk for 2D arrays and sorted in (untested since you didn't provide any sample input):
awk -F, '
BEGIN { PROCINFO["sorted_in"] = "#val_num_desc" }
{ for (i=1; i<=NF; i++) cnt[i][$i]++ }
END {
for (i=1; i<=NF; i++)
for (val in cnt[i])
print val, cnt[i][val] > ("outfile" i ".csv")
}
' infile.csv
No need for half a dozen different commands, pipes, etc.

Answer 2

You want to loop through the columns and perform the same command in each one of them. So what you are doing is fine: pass the column name to awk. However, you need to pass the value differently, so that it is an awk variable:
for i in {1..10}
do
awk -F ',' -v col=$i '{print $col}' infile.csv | sort | uniq -c | sort -nr > outfile$i.csv
^^^^^^^^^^^^^^^^^^^^^^^^
done