topic Re: Simple Script Problem - reordering in Operating System - HP-UX

Simple Script Problem - reordering

Russ Hancock_1 — Wed, 24 Jul 2002 05:57:38 GMT

Does anyone know how I can reorder a file, so the first line of the input file becomes the last line of the output file, and so on through out the input file...

I don't want it sorted, just reversed...

Thanks in advance.
Russ.

Re: Simple Script Problem - reordering

U.SivaKumar_2 — Wed, 24 Jul 2002 06:05:05 GMT

Hi,
If you know total number of lines of that file
you can do this for file of 900 lines.
#tail -n 900 myoriginalfile > invertedfile

#man tail for more details.

regards,
U.SivaKumar

Re: Simple Script Problem - reordering

Steve Steel — Wed, 24 Jul 2002 06:07:19 GMT

Hi

nl -ba -s"~" file|sort -r|cut -f2-256 -d"~"

Use umlaut or something else for field definition see man

steve Steel

Re: Simple Script Problem - reordering

Ralph Grothe — Wed, 24 Jul 2002 06:48:27 GMT

Hi Russ,

this is yet another task for Perl ;-)

But beware, this is a resource greedy solution as it requires the size of your file from memory stack, since we store the whole file in an array first.
So you shouldn't do this with really big files:

perl -e '@tmp = reverse <>;print @tmp' /path/to/your/file

Unfortunately, if you have big files, something more elaborate is needed, which I imagine would require seek().

HTH
Ralph

Re: Simple Script Problem - reordering

Russ Hancock_1 — Wed, 24 Jul 2002 07:01:29 GMT

Here's what I did in the end.
Thanks All.

INPUT=$1
OUTPUT=$2

rm -f $OUTPUT

LINES=`wc -l $INPUT|awk '{print $1}'`

i=0

while test i -lt $LINES
do
i=`expr $i + 1`
echo " $i \c"
tail -n $i $INPUT | head -n 1 | tee -a $OUTPUT
done

Re: Simple Script Problem - reordering

john korterman — Wed, 24 Jul 2002 07:07:10 GMT

Hi,
you could try this rather simple solution:

#!/usr/bin/sh

# reverse order of inputlines in $1

PREVIOUS_FILE=/tmp/prev
if [ -w $PREVIOUS_FILE ]
then
rm $PREVIOUS_FILE
fi
touch $PREVIOUS_FILE

CURRENT_FILE=/tmp/curr
if [ -w $CURRENT_FILE ]
then
rm $CURRENT_FILE
fi
touch $CURRENT_FILE

cat $1| while read CURRENT
do
echo $CURRENT > $CURRENT_FILE
cat $PREVIOUS_FILE >> $CURRENT_FILE
cat $CURRENT_FILE > $PREVIOUS_FILE
done
cat $CURRENT_FILE

regards,

John K.

Re: Simple Script Problem - reordering

V. V. Ravi Kumar_1 — Wed, 24 Jul 2002 07:29:30 GMT

hi,

try this
cat -n |sort -r|cut -f2 >

regds

Re: Simple Script Problem - reordering

H.Merijn Brand (procura — Wed, 24 Jul 2002 08:23:21 GMT

When using perl, you can use http://search.cpan.org/search?dist=File-ReadBackwards which is not that resource greedy

Re: Simple Script Problem - reordering

Peter Godron — Wed, 24 Jul 2002 09:26:32 GMT

Russ,
you could also try:
grep -n ^ input-file | sort -kr1n,1n | awk -F':' '{print $2}'

Re: Simple Script Problem - reordering

Aashish Raj — Wed, 24 Jul 2002 19:59:36 GMT

#! /usr/bin/ksh
i=1
cat file.txt|while read xx
do
buf[$i]=`echo $xx`
i=$((i+1))
done
v=$((i-1))
while true
do
if [ $v -ge 1 ];then
echo ${buf[$v]}
v=$((v-1))
else
exit
fi
done

Thanks
AR

Re: Simple Script Problem - reordering

James R. Ferguson — Wed, 24 Jul 2002 20:42:34 GMT

Hi Russ:

Here's one way:

# awk '{array [NR]=$0}; END{for (i=NR;i>0;i--) print array [i]}' inputfile > outputfile

Regards!

...JRF...

Re: Simple Script Problem - reordering

Reinhard Burger — Thu, 25 Jul 2002 07:43:34 GMT

HI
I would prefer the solution f U.Sivakumar
because it follows my most important approach : Keep it simple

just use:
tail -10000000000 oldfile > newfile

it's a silly way just to use a very very big number for tail but IT WORKS and you get what you want.
As long as your file does not have that big amount of lines you will get the file "oldfile" listed into "newfile" in reverse order.

Re: Simple Script Problem - reordering

Scott Williams_5 — Thu, 25 Jul 2002 12:36:31 GMT

Hi Russ,

Try this:

ed yourfile <g/^/m0
w
EOD

Re: Simple Script Problem - reordering

Ralph Grothe — Thu, 25 Jul 2002 13:35:25 GMT

Hey procura,

thanks for the hint towards File::ReadBackwards module from CPAN

http://search.cpan.org/doc/URI/File-ReadBackwards-0.97/ReadBackwards.pm

Haven't stumbled yet over this one.
Of course this is *much* better than what I suggested as a quick one-liner.

I will definitely install this one.
It's always worth to dig the CPAN first

:-)

Re: Simple Script Problem - reordering

Shannon Petry — Thu, 25 Jul 2002 14:15:54 GMT

For you two who said to use the tail command to do this, I have a suggestion for you. Know what you are saying before giving answers on the forums!

Tail DOES NOT reverse order display of files, simply takes the last "n" lines of the file to stdout.

I.E. (yes I clipped the last two lines of cat)
cat /etc/hosts
127.0.0.1 localhost
10.37.161.12 sh0su012 tr0su010 loghost

tail -2 /etc/hosts
127.0.0.1 localhost
10.37.161.12 sh0su012 tr0su010 loghost

Doh, they are identical....
Look at the other suggestions for your answers and ignore the suggestions of using the tail command.

Regards,
Shannon

Re: Simple Script Problem - reordering

Rodney Hills — Thu, 25 Jul 2002 14:21:32 GMT

Also "tail" does have a limitation on how many lines it can process.

If you say tail -1000000, tail does a sequential read and has to keep the last 1000000 lines in memory. Sometime tail doesn't allocate enough memory, and I've seen where it just drops off the remaining lines.

My 2 cents...

-- Rod Hills

Re: Simple Script Problem - reordering

Shannon Petry — Thu, 25 Jul 2002 18:45:50 GMT

Sadly the guy who said tail for this got 9 points and a magic answer....guess the user didnt test it, just had faith.. ;(

Re: Simple Script Problem - reordering

Reinhard Burger — Fri, 26 Jul 2002 04:44:03 GMT

Ok Guys
You got me !!!
Next time i'm hopefully a little bit mor carefull
:;-)

Re: Simple Script Problem - reordering

Suhas_2 — Fri, 26 Jul 2002 05:17:23 GMT

Hi Guys,
Here are my 2 cens.
On Solaris, IBM-AIX and DIGITAL a mere
"tail -r /path/to/file/filename"
would do the job. On HP-UX "-r" option is not available.

Rgds..
Suhas.

Re: Simple Script Problem - reordering

U.SivaKumar_2 — Fri, 26 Jul 2002 05:38:10 GMT

Hi Shanon,
I do agree that. I posted a theory that i have not tried practically. I regret , If i have hurted you all.

regards,
U.SivaKumar