Probably the easiest way to count number of columns in CSV file using bash shell is simply count number of commas in a single row. In the following example the content of the file myfile.csv is:
$ cat myfile.csv
1,2,3,4,5
a,b,c,d,e
a,b,c,d,e
This is a companion discussion topic for the original entry at https://linuxconfig.org/how-to-count-number-of-columns-in-csv-file-using-bash-shell