Add blank lines

jepeto · #1 (**permalink**) 07-11-2009

Hi!

I am trying to add blank lines at the end of a text file just before the last line. (This is a part of a script)

For example this is my text file... lines with dashes are included

Quote:

--------------------

this is an example of
my lack of
knowledge to use the
sed editor

--------------------

The problem is that i dont know before hand the number of blank lines to be added. The number of blank lines are determined by a variable and they are not always the same

ex
> echo $a
> 4

So the sed command....

Code:

sed '/-----------/s/^/\n\n\n\n&/g' myfile.txt

....does not do the job
What i need is to use my variable output in a command to add the blank lines

Any help will be appreciated

Franklin52 · #2 (**permalink**) 07-11-2009

An approach with awk:

Code:

number=4

awk -v var=$number -v n=$(wc -l < myfile.txt) 'NR==n{for(i=1;i<=var;i++){print ""}}1' myfile.txt

jepeto · #3 (**permalink**) 07-11-2009

Thank you for the reply Franklin52
I dont know why but that didnt work for me.
The output i get is exactly what i have in my text file
It does not add any blank lines to it

---------- Post updated at 05:17 PM ---------- Previous update was at 05:00 PM ----------

It works fine now
I just had to add awk '{ print $1 }' to your command

Code:

awk -v var=$number -v n=$(wc -l < myfile.txt | awk '{ print $1 }') 'NR==n{for(i=1;i<=var;i++){print ""}}1' myfile.txt

Thanks for the help Franklin52!!!!

scottn · #4 (**permalink**) 07-11-2009

I tried it in sed and gave up after three attempts, so as a complete alternative!...

Code:

head -$(echo $(($(cat myfile.txt| wc -l)-1))) myfile.txt; echo; tail -1 myfile.txt

awk rules!

nj78 · #5 (**permalink**) 07-11-2009

Yeah, awk lets put in loop. This is one of those times I like the x operator in Perl. Thanks.

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