sed question...

[Giorgos Keramidas]

On 2007-09-24 20:52, Gary Kline <kline at tao.thought.org> wrote:
>On Mon, Sep 24, 2007 at 11:07:20PM -0400, Howard Goldstein wrote:
>>>  # delete the last 10 lines of a file
>>>  sed -e :a -e '$d;N;2,10ba' -e 'P;D'   # method 1
>>>  sed -n -e :a -e '1,10!{P;N;D;};N;ba'  # method 2
>>> 
>>> 	Question two, can sed do its thing inline?
>> 
>> Wouldn't it be easier to use  head -n 18 ?

If you _know_ that the file has 28 lines, yes.  If you don't,
then itmay be tricky to 'guess' that -n 18 is the right option.

> No, because most of these files are between 40 and 50 lines.  I only
> care about the first 30 or 40; everything below has to be deleted.  By
> hand, using vi, I might type :31,$d that fixes that one file.  Of
> course, I could simply edit in "19" for "10" above.  It would be more
> savvy to understand the sed syntax.

You don't need to manually edit files with vi(1) if all you want to do
is type ``:31,$d<RET>:wq<RET>'' ...

	sed -i '' -e '31,$d' file.txt