Shell – How to sort a collection of lines from different files

shell-scriptsorttext processing

I want to sort second line in each file by second column, and also print name of the corresponding file. I am doing it like this –

rm tmp;
for filename in file*; do
  num=`head -2 $filename | tail -1 | awk '{print $2}'`;
  echo "$filename $num" >> tmp;
done;
sort -n -k2,2 tmp

Can it be done in a better way that doesn't include a tmp file?

Best Answer

Try:

$ awk 'FNR == 2' file1 file2 filen | sort -n -k2,2

With gawk, you can use nextfile for efficience:

$ gawk 'FNR == 2 {print FILENAME,$2; nextfile}' file1 file2 filen | sort -n -k2,2

or you can write your own nextfile function in other awk implementation refer to this.

If you don't have gawk, you can use perl for more portable:

$ perl -anle 'print "$ARGV $F[1]" and close ARGV if $. == 2' file1 file2 filen |
  sort -n -k2,2
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