The basic use awk

awk 【optios】program 

program: between statements separated by semicolons

                   print    printf

Options: -F used when specified input field separator

           -v var = value: Custom Variables

1、print item1，item2

             Points: 1, separated by commas

                       2, the output of each item may be a string, or may be values: representation of the current record fields, or variables of awk

                       3, as will be omitted item corresponding to print $ 0

 2, variable

            2.1 built-in variables

                FS: input field seperator: default blank character

               OFS: out put field seperator default blank character

               RS: line feed input at input record seperato

              ORS: when the line breaks output record seperato output

              NF: number of fields

             NR: The number of rows

             FNR: each of the files are counted

            FILENAME; filename

            ARGC: the number of command line arguments

           ARGV: array, save the command line given the parameters

           BEGIN: a line of data