awk.md

awk

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Print the n-th column

awk '{print $n}'  

echo "a b c d" | awk '{print $2}'  # Output: b

Print specific lines of a file

cat file.txt | awk '{if (NR>=123 && NR<=125) print}'

NR: The ordinal number of the current record from the start of input. Inside a BEGIN action the value shall be zero. Inside an END action the value shall be the number of the last record processed.

Print date and time columns

ls -l | sed '1d' | awk '{print $6,$7}'  

Replace new lines

cat file.txt | awk '{printf $0}'      # …with nothing.
cat file.txt | awk '{printf $0 " "}'  # …with spaces.

Format output using a variable and a column from the file

%-10s = adding spaces to the right.
%6s = right align, adding spaces to the left.

cat $filename | awk "{printf \"│ %-10s │ %6s │\", \"$filename\", \$2}"