This slide illustrates the record and field parsing awk performs.

Awk splits a records, reading one at a time, and on each pass assigns that record to $0. By default, RS is assigned by default the newline (\n). You have the option to assign RS your own value.

After $0 has been assigned the respective record, it will then split the record into positional parameters. By default, the field separator is white space; which can be any combination of spaces and tabs. You can assign a different value to designate the field separator. For example you can assign FS=“:” when the colon character serves as the field separator.

We’ll see some examples of reassigning these values later.

After understanding how records and records are parsed, the following becomes much clearer in the awk process:

• Read in a record determined by the RS variable.
• Split the record into fields determined by FS variable.
• For each record, determine if the pattern match is satisfied:
  • If True, perform the corresponding action.
  • If False, the next pattern is checked.
  • After all patterns for input are processed, process the next record.
• A pattern without an action prints the entire record.
• An action without a pattern will print the entire record which satisfies the match.