Famous Awk One-Liners Explained, Part I: File Spacing, Numbering and Calculations

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kyaw Permalink
April 12, 2011, 06:10

Hi
if code goes like as awk '{ print ++a, $0 }', line numbering included blank lined. But code goes awk 'NF {$0=++a ": " $0}; {print}' that will be add line number to non-blank line.

NF {$0=++a ": " $0} = There must have one field at lease to increase number to var "a" else no action or not take as record for blank line, same time $0 (whole NR ) will become as [var a : ORG_LINE] then print again with all (whole line which newly create include var a value) by print statement after ; .

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kyaw Permalink
April 12, 2011, 06:12

Correction : ---
if code goes like as awk '{ print ++a, $0 }', line numbering included blank lined. But code goes awk 'NF {$0=++a ": " $0}; {print}' that will be add line number only to non-blank line. Blank will not get line number.

NF {$0=++a ": " $0} = There must have one field at lease to increase number to var "a" else no action or not take as record for blank line, same time $0 (whole NR ) will become as [var a : ORG_LINE] then print again with all (whole line which newly create include var a value) by print statement after ; .

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