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 Forum index » Advanced Topics » Cutting edge
Help needed getting ramdisk_size using AWK (or sed) (SOLVED)
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pakt


Joined: 04 Jun 2005
Posts: 1089
Location: Sweden
PostPosted: Sun 30 Oct 2005, 05:08    Post subject:  Help needed getting ramdisk_size using AWK (or sed) (SOLVED)  
I'm working on an update to WakePup 1.0 that will also boot non-standard Puppies (Chubby, Murga, PizzaPup, etc) that use the ramdisk_size=xxxxx parameter when booting.

Some help is needed in extracting ramdisk_size=xxxxx from either isolinux.cfg (on CD) or syslinux.cfg (on USB flash drive).

The tools I have at hand are AWK & sed for DOS.

Here are extracts showing the relevant lines in the files:

(From puppy-1.0.5-mozilla-128Mb-Murga's isolinux.cfg)

Code:
default 1
DISPLAY BOOT.MSG
prompt 1
label 1
 kernel vmlinuz
 append root=/dev/ram0 initrd=image.gz ramdisk_size=63488 PFILE=pup001-none-262144
<--snip-->


(And from a modified puppy-1.0.5-mozilla-128Mb-Murga USB syslinux.cfg)

Code:
default vmlinuz root=/dev/ram0 initrd=image.gz
append ramdisk_size=63488 PSLEEP=25 PHOME=sda1 PFILE=pup100-none-262144 PKEYS=uk


What I have succeded in doing so far is to extract ramdisk_size=63488 like this (remember, I'm using AWK for DOS punctuation (" instead of '):

Code:
M:\awk "/ramdisk_size/{print \"set rdsize=\" $2;exit;}" %pupdrv%\syslinux.cfg >M:\tmp_.bat
call M:\tmp_.bat
del M:\tmp_.bat >NUL


This will set the FreeDOS environment variable rdsize=ramdisk_size=63488 and WakePup can then successfully boot into Puppy using this. Note that this only works when the variable is found in field #2. That's where the potential problem lies: the boot parameters can be written in a different order - ramdisk_size doesn't have to be in field #2, someone might place it at the end of the parameter line...

So here's the question: can anyone with a better knowledge of AWK syntax than me (that's just about anyone Wink) show me how to extract 'ramdisk_size=XXXXX' regardless of which field it is in?

Thanks in advance for any help Smile

Paul
Last edited by pakt on Mon 31 Oct 2005, 06:41; edited 1 time in total
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rarsa


Joined: 29 May 2005
Posts: 3053
Location: Kitchener, Ontario, Canada
PostPosted: Sun 30 Oct 2005, 12:04    Post subject:  
Can there be spaces around the '=' ?

e.g.
Code:
append root =/dev/ram0 initrd= image.gz ramdisk_size = 63488 PFILE = pup001-none-262144
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rarsa


Joined: 29 May 2005
Posts: 3053
Location: Kitchener, Ontario, Canada
PostPosted: Sun 30 Oct 2005, 12:20    Post subject:  
I know that you said that you only had access to awk and sed. but... do you have access to grep?

Code:
grep -o 'ramdisk_size[ ]*=[ ]*[0-9]*'  %pupdrv%/syslinux.cfg


This gives you exactly what you are asking for. In any event, That's the regular expression you want to use to find the ramdisk_size even if you are not using grep.
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rarsa


Joined: 29 May 2005
Posts: 3053
Location: Kitchener, Ontario, Canada
PostPosted: Sun 30 Oct 2005, 12:51    Post subject:  
With awk there are different ways of doing it as it is a rich language.

Here is a one liner that does what you want:

Code:
awk '{ if(match($0,"ramdisk_size[ ]*=[ ]*[0-9]*")) printf(substr($0,RSTART,RLENGTH))}'  %pupdrv%/syslinux.cfg


That will handle spaces around the = sign and will return the ramdisk_size=63488 without a newline at the end.

I'm also a novice in awk (I've just written two awk commands in my life... this being the second one) but I've found some good resources like this tutorial http://www.grymoire.com/Unix/Awk.html#uh-47
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pakt


Joined: 04 Jun 2005
Posts: 1089
Location: Sweden
PostPosted: Sun 30 Oct 2005, 15:03    Post subject:  
rarsa, thanks for your responses.

rarsa wrote:
With awk there are different ways of doing it as it is a rich language.

Yes, it certainly seems to be a cryptic but powerful language. I've searched high and low on the internet and found ways of doing just about anything...except what I want Confused

As I just needed it to solve one problem, I've tried to avoid having to learn the details - there is quite a learning curve - and it would just take too long.

rarsa wrote:
Here is a one liner that does what you want:

Code:
awk '{ if(match($0,"ramdisk_size[ ]*=[ ]*[0-9]*")) printf(substr($0,RSTART,RLENGTH))}'  %pupdrv%/syslinux.cfg


That will handle spaces around the = sign and will return the ramdisk_size=63488 without a newline at the end.

Tried your one-liner but got the following error:

Code:
{ if(match($0,ramdisk_size[
awk: line 0: syntax error


rarsa wrote:
I'm also a novice in awk (I've just written two awk commands in my life... this being the second one) but I've found some good resources like this tutorial http://www.grymoire.com/Unix/Awk.html#uh-47

Thanks, I'll take a look at it.

Otherwise, while I have been waiting for a response to my post, I actually managed to patch together something that works and will give the right parameter regardless of which field it is in:

awk "/ramdisk_size/{for(i=1;i<=NF;i++){if($i~/ramdisk_size/)print \"set rdsize=\" $i};exit;}" isolinux.cfg >tmp_.bat
call tmp_.bat
del tmp_.bat >NUL

I got this working after looking at many AWK examples (books & internet) and a lot of trial and error. So it looks like I'll be able to finish my updated WakePup soon after all.

Very Happy
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pakt


Joined: 04 Jun 2005
Posts: 1089
Location: Sweden
PostPosted: Sun 30 Oct 2005, 15:11    Post subject:  
rarsa wrote:
Can there be spaces around the '=' ?

e.g.
Code:
append root =/dev/ram0 initrd= image.gz ramdisk_size = 63488 PFILE = pup001-none-262144

In response to your question about spaces, AWK uses spaces as delimiters by default. Therefore the single field 'ramdisk_size=63488' would become three fields instead.

I hope that that variation (having spaces around the '=') in isolinux.cfg or syslinux.cfg isn't allowed by Barry's scripts, otherwise it will be back to the drawing board for me.
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pakt


Joined: 04 Jun 2005
Posts: 1089
Location: Sweden
PostPosted: Sun 30 Oct 2005, 15:28    Post subject:  
rarsa wrote:
I know that you said that you only had access to awk and sed. but... do you have access to grep?

Code:
grep -o 'ramdisk_size[ ]*=[ ]*[0-9]*'  %pupdrv%/syslinux.cfg


This gives you exactly what you are asking for. In any event, That's the regular expression you want to use to find the ramdisk_size even if you are not using grep.

Just tried your 'grep' suggestion, but I don't get any output. I had to change the ' to " to work in DOS, like this:

grep -o "ramdisk_size[ ]*=[ ]*[0-9]*" syslinux.cfg

This was using 'Turbo GREP 5.5 Copyright (c) 1992, 1999 Inprise Corporation'

EDIT: Used wrong syslinux file with above example Embarassed. With isolinux.cfg, the grep expression outputs all four _complete_ lines containing the parameter Sad

I also tried with another grep I had (GNU grep 2.0 (MS-DOS rev A)), but it didn't recognize the -o flag. Sad
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BarryK
Puppy Master


Joined: 09 May 2005
Posts: 7047
Location: Perth, Western Australia
PostPosted: Sun 30 Oct 2005, 21:26    Post subject:  
Anywhere my scripts have generated ramdisk_size=65536, it is without spaces.
Of course, if someone has manually edited the file that's another matter, but nowhere in any examples or documentation do I show it with spaces, so I reckon you will be safe to assume no spaces.
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rarsa


Joined: 29 May 2005
Posts: 3053
Location: Kitchener, Ontario, Canada
PostPosted: Sun 30 Oct 2005, 23:45    Post subject:  
patk wrote:
Tried your one-liner but got the following error:
Code:

{ if(match($0,ramdisk_size[
awk: line 0: syntax error
I just tried it again and it works in puppy, that tells me that the problem is with the awk you are using or the regular expressions evaluator it uses.

I was going for the loop too, but I found that a one liner was better. Anyway, I'm glad it's working for you.

patk wrote:
With isolinux.cfg, the grep expression outputs all four _complete_ lines containing the parameter
The -o parameter tells grep to output just the text that matches the regular expression, not the whole line. Is there another option in turbo grep that would do this?
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MU


Joined: 24 Aug 2005
Posts: 13642
Location: Karlsruhe, Germany
PostPosted: Mon 31 Oct 2005, 00:37    Post subject:  
try http://unxutils.sf.net
The included grep supports -o

Mark
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MU


Joined: 24 Aug 2005
Posts: 13642
Location: Karlsruhe, Germany
PostPosted: Mon 31 Oct 2005, 00:49    Post subject:  
with unxutils you can do:
grep ramdisk_size isolinux.cfg|sed s/^.*ramdisk_size=\([0-9]*\).*$/\1/ >test.txt

At least on WinXP.

Mark
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pakt


Joined: 04 Jun 2005
Posts: 1089
Location: Sweden
PostPosted: Mon 31 Oct 2005, 05:47    Post subject:  
MU wrote:
with unxutils you can do:
grep ramdisk_size isolinux.cfg|sed s/^.*ramdisk_size=\([0-9]*\).*$/\1/ >test.txt

At least on WinXP.

Thanks Mark. Seems that unxutils is for win32, but I did find some more grep's that worked with DOS (unfortunately I can't find one that supports the -o flag).

Here is the output I get with your example where isolinux.cfg contains three lines with the parameter ramdisk_size=13312:
13312
13312
13312

This would be a good solution except that I want just a single '13312' - not three. Is there a way of doing that?
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Guest
Guest
PostPosted: Mon 31 Oct 2005, 06:08    Post subject:  
in linux, you could pipe it through head -n1
there should be a port of head somewhere
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pakt


Joined: 04 Jun 2005
Posts: 1089
Location: Sweden
PostPosted: Mon 31 Oct 2005, 06:40    Post subject:  
Seems I managed to solve it myself Smile

Using Mark's example and 'GNU UNIQ, textutils version 1.2' for DOS like this:

grep ramdisk_size isolinux.cfg|sed s/^.*ramdisk_size=\([0-9]*\).*$/\1/ | uniq >test.txt

...outputs a single '13312' instead of three.

Now I have two solutions...

Thanks to everyone for suggestions & info Very Happy
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MU


Joined: 24 Aug 2005
Posts: 13642
Location: Karlsruhe, Germany
PostPosted: Mon 31 Oct 2005, 06:48    Post subject:  
ftp://garbo.uwasa.fi/pc/unix/gnuegrep.zip
ftp://garbo.uwasa.fi/pc/unix/sed15.zip
ftp://garbo.uwasa.fi/pc/unix/tail20.zip

from http://garbo.uwasa.fi/pc/unix.html

They work in Dosbox, but I can't get the "|" -character on my keyboard in Dosbox, so I can't test the whole expression.

try
grep ramdisk_size isolinux.cfg | sed "s/^.*ramdisk_size=\([0-9]*\).*$/\1/" | tail -n 1

Mark
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