Raw Input		Desired Output
(p1,line-1) (p1,line-2) (p1,line-3) (p2,line-1) (p2,line-2) (p3,line-1) (p3,line-2) (p3,line-3) (p3,line-4)		(p1,line-1) (p2,line-1) (p3,line-1)

Script and Comments

Script₁

[ 1] /^$/{
[ 2] h
[ 3] d
[ 4] }
[ 5] x
[ 6] /^$/!d
[ 7] g

Comments

'Hold Space' is abbreviated to 'HS'.
A different approach is used to develop this script in which
- HS is used as a flag,
- which is set if HS is not empty, clear otherwise.
- for each non-blank line, if the flag is clear, then print it; otherwise, discard it.
Each time a blank line is read, Step [2] will overwrite HS with this blank line (i.e., clear the flag) to ensure the first non-blank line following it will be printed.
Each time a non-blank line is read, Steps [5] and [6] are used to check the flag:
- if the flag is set, then discard that line;
- otherwise, Step [7] will get that line from HS.
- after Step [6], the flag is set since HS is not empty.\

Script₂

[ 1] /^$/h
[ 2] x
[ 3] /^$/!d
[ 4] g
[ 5] /^$/d

Comments