Most useful awk programs

awk '{ if (NF > max) max = NF }
     END { print max }'
    This program prints the maximum number of fields on any input line. 
awk 'length($0) > 80'
    This program prints every line longer than 80 characters. The sole rule has
    a relational expression as its pattern, and has no action (so the default
    action, printing the record, is used).
awk 'NF > 0'
    This program prints every line that has at least one field. This is an easy
    way to delete blank lines from a file (or rather, to create a new file
    similar to the old file but from which the blank lines have been deleted).
awk '{ if (NF > 0) print }'
    This program also prints every line that has at least one field. Here we
    allow the rule to match every line, then decide in the action whether to
    print.
awk 'BEGIN { for (i = 1; i <= 7; i++)
               print int(101 * rand()) }'
    This program prints 7 random numbers from 0 to 100, inclusive. 
ls -l files | awk '{ x += $4 } ; END { print "total bytes: " x }'
    This program prints the total number of bytes used by files. 
expand file | awk '{ if (x < length()) x = length() }
                  END { print "maximum line length is " x }'
    This program prints the maximum line length of file. The input is piped
    through the expand program to change tabs into spaces, so the widths
    compared are actually the right-margin columns.
awk 'BEGIN { FS = ":" }
     { print $1 | "sort" }' /etc/passwd
    This program prints a sorted list of the login names of all users. 
awk '{ nlines++ }
     END { print nlines }'
    This programs counts lines in a file. 
awk 'END { print NR }'
    This program also counts lines in a file, but lets awk do the work. 
awk '{ print NR, $0 }'
    This program adds line numbers to all its input files, similar to `cat -n'.
awk -F "\"*,\"*" '{print $3}' file.csv
    CSV parsing, prints 3rd field