[ale] Move last line of a file to first line

Thu Mar 29 09:11:30 EDT 2012

The lines on size were a scream!

On Thu, Mar 29, 2012 at 9:01 AM, Ed Cashin <ecashin at noserose.net> wrote:

> Thanks, although it wasn't meant to be a bat.  :)  Because ed is on plan
> 9, Solaris, Linux, and Mac, out of the box and pretty consistently, I used
> it as a real interactive editor for a while, after Brantley Coile told me
> that using it made a difference in the way he thought about his code.
>
> I found it to be a surprisingly useful editor and am fond of it now even
> though I've gone back to using bigger, less ubiquitous interactive editors.
>
> There's a funny page about ed that y'all might have already seen:
>
>   http://www.gnu.org/fun/jokes/ed.msg
>
>
> On Thu, Mar 29, 2012 at 8:09 AM, Jim Kinney <jim.kinney at gmail.com> wrote:
>
>> I must now add ed to my daily tool pile. grep, awk [s]ed, vi[m], bash.
>>
>> That was a very good "clue bat" on why ed should still be used. a 1M line
>> file would be easy for ed but pain for sed.
>>
>> Thanks!
>>
>> On Wed, Mar 28, 2012 at 9:57 PM, Ed Cashin <ecashin at noserose.net> wrote:
>>
>>> Thanks for mentioning the non-stream editor!  They made sed for streams,
>>> because ed is for files.  It is at times like this when I sincerely regret
>>> the way distros are beginning to omit ed for the first time in decades.
>>>
>>> There's an ed move command called "m".  Move this line to that line.
>>> The one liner below does the same thing as this interactive session
>>>
>>> $m0
>>> w
>>> q
>>>
>>> ecashin at reynolds:~$ head /etc/passwd | nl > ~/tmp/a
>>> ecashin at reynolds:~$ cp ~/tmp/a ~/tmp/b
>>> ecashin at reynolds:~$ printf '$m0\nw\nq\n' | ed ~/tmp/b
>>> 414
>>> 414
>>> ecashin at reynolds:~$ diff -u ~/tmp/a ~/tmp/b
>>> --- /home/ecashin/tmp/a 2012-03-28 21:40:25.000000000 -0400
>>> +++ /home/ecashin/tmp/b 2012-03-28 21:41:44.000000000 -0400
>>> @@ -1,3 +1,4 @@
>>> +    10 news:x:9:9:news:/var/spool/news:/bin/sh
>>>       1 root:x:0:0:root:/root:/bin/bash
>>>       2 daemon:x:1:1:daemon:/usr/sbin:/bin/sh
>>>       3 bin:x:2:2:bin:/bin:/bin/sh
>>> @@ -7,4 +8,3 @@
>>>       7 man:x:6:12:man:/var/cache/man:/bin/sh
>>>       8 lp:x:7:7:lp:/var/spool/lpd:/bin/sh
>>>       9 mail:x:8:8:mail:/var/mail:/bin/sh
>>> -    10 news:x:9:9:news:/var/spool/news:/bin/sh
>>> ecashin at reynolds:~$
>>>
>>> On Wed, Mar 28, 2012 at 12:41 PM, Richard Bronosky <Richard at bronosky.com
>>> > wrote:
>>>
>>>> Be careful doing this with large files. You are storing the whole file
>>>> in memory.
>>>>
>>>> I would do this in 2 passes.
>>>>
>>>> # First get the last line into a new file. (assuming the file in
>>>> question is passed in as the first argument)
>>>> tail -n1 $1 > $1.mod
>>>> # Second add the rest of the file, less the last line.
>>>> sed '$d' $1 >> $1.mod
>>>>
>>>> This is working with streams. It requires an additional $filesize of
>>>> disk space, but it does not require $filesize of RAM.
>>>>
>>>> If you want to be really efficient, use ed. ;-)
>>>> # This will trim the last line of the file in place, but I'm not
>>>> taking the time to figure out how to add it to the beginning.
>>>> ed "$1" << EOF
>>>> $
>>>> d
>>>> w
>>>> EOF
>>>>
>>>> On Mar 28, 2012 11:19 AM, "Lightner, Jeff" <JLightner at water.com> wrote:
>>>> >
>>>> > I found this works:
>>>> >
>>>> > awk '{a[NR]=$0} END {print a[NR]; for (i=1;i<NR;i++) print a[i]}'
>>>> originalfile >newfile
>>>> >
>>>> >
>>>> >
>>>> > Where you replace originalfile and newfile with real file names.
>>>> >
>>>> >
>>>> >
>>>> >
>>>> >
>>>> >
>>>> >
>>>> > ________________________________
>>>> >
>>>> > From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of
>>>> Lightner, Jeff
>>>> > Sent: Wednesday, March 28, 2012 11:10 AM
>>>> > To: Atlanta Linux Enthusiasts
>>>> > Subject: [ale] Move last line of a file to first line
>>>> >
>>>> >
>>>> >
>>>> > We have variable length text files being received in which the
>>>> “header” line we use in automated processing is the last line of the file
>>>> rather than the first line.
>>>> >
>>>> >
>>>> >
>>>> > What is the best way to move that last line of a text file to be the
>>>> first line?
>>>> >
>>>> >
>>>> >
>>>> > Please answer the question as asked and don’t suggest making the file
>>>> be in the correct order when we receive it or changing the automated
>>>> processing to read the last line first.  Assume those aren’t options.
>>>> >
>>>> >
>>>> >
>>>> > What I came up with was to do tail -1 >newfile and head -<number of
>>>> lines – 1> but was thinking there ought to be a better way.
>>>> >
>>>> >
>>>> >
>>>> > I see sed can deal with last line, first line and insertion but the
>>>> examples I’m finding address either/or not moving last line to first line.
>>>> >
>>>> >
>>>> >
>>>> >
>>>> >
>>>> >
>>>> >
>>>> >
>>>> >
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>>>
>>>
>>>
>>> --
>>>   Ed Cashin <ecashin at noserose.net>
>>>   http://noserose.net/e/
>>>   http://www.coraid.com/
>>>
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>>>
>>
>>
>> --
>> --
>> James P. Kinney III
>>
>> As long as the general population is passive, apathetic, diverted to
>> consumerism or hatred of the vulnerable, then the powerful can do as they
>> please, and those who survive will be left to contemplate the outcome.
>> - *2011 Noam Chomsky
>>
>> http://heretothereideas.blogspot.com/
>> *
>>
>> _______________________________________________
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>> http://mail.ale.org/mailman/listinfo
>>
>>
>
>
> --
>   Ed Cashin <ecashin at noserose.net>
>   http://noserose.net/e/
>   http://www.coraid.com/
>
> _______________________________________________
> Ale mailing list
> Ale at ale.org
> http://mail.ale.org/mailman/listinfo/ale
> See JOBS, ANNOUNCE and SCHOOLS lists at
> http://mail.ale.org/mailman/listinfo
>
>

-- 
-- 
James P. Kinney III

As long as the general population is passive, apathetic, diverted to
consumerism or hatred of the vulnerable, then the powerful can do as they
please, and those who survive will be left to contemplate the outcome.
- *2011 Noam Chomsky

http://heretothereideas.blogspot.com/
*
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