topic Re: Delete last two lines in Operating System - HP-UX

Delete last two lines

parmy_4 — Thu, 26 Aug 2004 06:10:07 GMT

Hi,
I have a file in which I don't need the last two lines. How can run a command to achieve this?

I have a work around for my collegue but he is not happy with it.

sed '$d' my_file | sed '$d'

I am expecting some thing like

sed -e '$d' -e '$d' my_file.

Please help us.
Parmy

Re: Delete last two lines

Pete Randall — Thu, 26 Aug 2004 06:21:31 GMT

Parmy,

Use "sed -e '$d' my_file |sed -e '$d'"

that should do it.

Pete

Re: Delete last two lines

harry d brown jr — Thu, 26 Aug 2004 06:23:19 GMT

vi my_file<
live free or die
harry

Re: Delete last two lines

Jean-Luc Oudart — Thu, 26 Aug 2004 06:32:10 GMT

with vi cmd
vi +$ my_file<
Regards
Jean-Luc

Re: Delete last two lines

harry d brown jr — Thu, 26 Aug 2004 06:57:56 GMT

Another way:

expr `wc -l my_file | cut -d" " -f1` - 2 | xargs echo | sed -e "s/^/head -/" -e "s/$/ my_file/" | sh > new_my_file

live free or die
harry

Re: Delete last two lines

john korterman — Thu, 26 Aug 2004 07:00:11 GMT

Hi,

I think this works (at least it seems so on my screen):

# tail -2 | comm -23 -

regards,
John K.

Re: Delete last two lines

Jean-Luc Oudart — Thu, 26 Aug 2004 07:21:32 GMT

awk solution :
awk -v nb=$(wc -l my_file | cut -f1 -d" ") '{if(NR>(nb - 2)) exit; print}' my_file

Regards,
Jean-Luc

Re: Delete last two lines

Elmar P. Kolkman — Thu, 26 Aug 2004 07:27:23 GMT

A possible solution:

head $(wc -l my_file | awk '{print "-" $1 - 2}') my_file

In vi you can use the command:
$-1,$d
to delete the last two lines. Should work in ed too.

Or a complete awk solution:
awk '{ if (NR > 2) { print prev2 } prev2=prev1;prev1=$0}' < my_file

Re: Delete last two lines

Bharat Katkar — Thu, 26 Aug 2004 07:42:29 GMT

Hi
This works ..but don't know you like it or not.

# let A=`cat file1 | wc -l`-2
# head -$A file1 >file2

That works.
Regards,

Re: Delete last two lines

Jan Sladky — Thu, 26 Aug 2004 08:03:45 GMT

hi Parmy,

I have no HP-UX where to try it but on Linux
exists the tac command (opposit to cat)

so maybe the following row will help you

tac file | sed '1,2d' | tac | tee file1

br Jan

Re: Delete last two lines

Rodney Hills — Thu, 26 Aug 2004 08:56:08 GMT

Here is a perl one-liner that only requires one pass through the file.

perl -ne 'push(@last2,$_); if (scalar @last2 > 2) { print shift @last2}'

By pushing each line onto a stack this script will not print the last 2 lines.

HTH

-- Rod Hills

Re: Delete last two lines

Rodney Hills — Thu, 26 Aug 2004 09:00:43 GMT

Parmy,

Assigning points to indicate which solution you think works the best is what helps the forum help others...

-- Rod Hills

Re: Delete last two lines

Rick Garland — Thu, 26 Aug 2004 09:13:26 GMT

cat $file | sed '1,2d'

Re: Delete last two lines

Hein van den Heuvel — Thu, 26 Aug 2004 09:15:05 GMT

Here is a one-pass in awk which does no create a temp file.
It uses a 'circular buffer' of the target 'missing line' count 'L'.
This is done with an array 'line' indexed by the current record number (NR) modulus that L.
You provide a desired value for L as argument.
We start printing from the array only after L lines have come by, 'falling behind' by L lines.

Sounds tricky? Here is the 'one line' code:

awk -vL=2 '{if(NR>L){print line[(NR-L)%L];line[NR%L]=$0}}' your-file

Hein.

Re: Delete last two lines

Elmar P. Kolkman — Fri, 27 Aug 2004 01:13:41 GMT

Hein, your solution is a variant of my awk solution... but my mathematic mind says you need to remove the -L in your solution. It does nothing in the end... since (NR-L)%L equals NR%L.
And you have a closing curly bracket wrong, resulting in missing the first lines...

So the right solution would be:

awk -vL=2 '{if(NR>L){print line[NR%L];}line[NR%L]=$0}' my_file

Re: Delete last two lines

Elmar P. Kolkman — Fri, 27 Aug 2004 01:18:32 GMT

Strange point assignment... I've tested the highest rated solution, but it doesn't seem to work. At least nog on the /etc/passwd files I have on Linux and HP-UX... But it could be me...

Re: Delete last two lines

Bharat Katkar — Fri, 27 Aug 2004 02:23:36 GMT

It looks like Parmy is taking it very lightly and on the contrary all the responders are struggling to be as perfect as possible..

Re: Delete last two lines

Hein van den Heuvel — Sat, 28 Aug 2004 08:37:27 GMT

Elmar> Hein, your solution is a variant of my awk solution...

Ayup, just a touch more general purpose. I had missed the awk part of your solution.

Elmar> but my mathematic mind says you need to remove the -L in your solution.

Ayup, a simplication I overlooked this time.

Elmar> It does nothing in the end... since (NR-L)%L equals NR%L.

Ayup, other then to make the code more clear.

Elmar> And you have a closing curly bracket wrong, resulting in missing the first lines...

Ooops! Thanks for catching that.

Groetjes,
Hein.