How does this gawk command work?

Question

I am trying to understand gawk in shell scripting.

How does this command work?

 gawk -vN="$N"

and this split based on what

 n=patsplit($0,a,/\<\w*\>/,s)

and this

PROCINFO["sorted_in"]="@val_num_desc"

How does it work?

Answer 1

• The first command passes an argument to gawk. The argument is N and the value assigned to N is the value of the bash variable $N.

• The second command splits the awk variable $0 into strings based on the regex /\<\w*\>/. It returns the number of strings that it was able to split. See http://www.gnu.org/software/gawk/manual/gawk.html#String-Functions. The regex is comopsed of \< (start of word boundary), \w (word constituent), \> (end of word boundary). See http://www.gnu.org/software/gawk/manual/gawk.html#GNU-Regexp-Operators

• The third command is a special feature of gawk version 4.1. That is used to traverse arrays in specific order (in a for loop).. See http://www.gnu.org/software/gawk/manual/gawk.html#Scanning-an-Array