Bash while sed is not null -

i need while loop when sed not null. example:

file 1

line1 line2 line3

file 2

i=1  while sed "${int}p" # here need expression checks if line not null # here echo line , i++

i tried write while sed -n "${int}p" not work expected.

you can use = command in sed number of lines:

 sed -n '/./!q;=;p' input | sed 'n;s/\n/ /'

for input:

a b c  d

this gives:

1 2 b 3 c

if want line number of line before first non-empty line:

sed -n '/./!q;=' input | tail -1

a while loop prints lines:

while read line;         echo "$line" done < input

Brazzel