How do I insert a line at a specific row in multiple files on Unix?

Question

I need to insert a line with specific text on the second line (thus moving the other lines down in the file) of hundreds of files in a directory. Any quick Unix tips on how that can be done?

Answer 1

sed -i -e '2iYour line here' /dir/*

Note that sed -i semantics vary by Unix flavor, so check your man sed. This is written for the GNU flavor.

Answer 2

this is an AWK use rather than the sed,

for i in $(<list_of_files)
do
     awk '{if (FNR!=2) print $0; 
           else { print "new line"; print $0}}' $i > ${i}.tmp;
     mv ${i}.tmp $i;
done

Answer 3

ls | xargs --replace=foo perl -i -ne 'print; print "second line text\n" unless $x++;' foo

Answer 4

perl -pi -we'print "extra line\n" if $. == 3; close ARGV if eof' files

The close(ARGV) is necessary to restart the line counter $. at the beginning of each file; by default, it counts lines across files.