What does the '-d' option in the 'cut' command specify?

The -d option in the cut command specifies the delimiter that separates fields in the input data. By default, cut uses a tab character as the delimiter, but you can change it to any character you want by using the -d option followed by the desired delimiter.

For example, if you have a comma-separated values (CSV) file and you want to extract the second field, you can use:

cut -d ',' -f 2 filename.csv

In this command, -d ',' sets the delimiter to a comma, and -f 2 specifies that you want to extract the second field.