How do I edit linuxrc correctly?

**probono** · 06-02-2003, 04:49 PM

I want to call a program that draws a graphic to the framebuffer during startup. I realized that I have to start that program in
linuxrc. But as soon as I change more than one line in linuxrc (inside miniroot.gz inside boot.img) the boot process breaks. Although if I just change something at the end of the script, its behavior changes already in the beginning (e.g. when it scans the different partitions for the Knoppix CD, it writes the pink lines *under* each other instead of *replacing* them /hda1 /hda2 ... etc)

How do I edit linuxrc correctly? Does it have to stay in the same size or why am I having this trouble?

I have tried it several times on different machines. Here is what I did:

loop-mount boot.img
unpack initrd.gz
loop-mount initrd.gz
edit linuxrc with kwrite
unmount initrd
pack initrd
replace initrd.gz

Where is the mistake?

**probono** · 06-03-2003, 09:52 PM

no one done that before?

**Pasq** · 06-04-2003, 08:06 PM

unfortunately

if I have some free time I will try to add something to it, but I don't know whet it will be.

**probono** · 06-13-2003, 10:19 PM

could *please* anyone who has successfully edited linuxrc explain how exactly you did it? I'm becoming crazy on this...

**Pasq** · 06-13-2003, 10:46 PM

Ok, i tried with success:

loop-mount boot.img
unpack miniroot.gz
loop-mount miniroot.gz
edit linuxrc with vim
unmount miniroot
pack miniroot (gzip -9)
replace miniroot.gz
umount boot.img

**probono** · 06-14-2003, 11:22 PM

Originally Posted by Pasq

Ok, i tried with success:

loop-mount boot.img
unpack miniroot.gz
loop-mount miniroot.gz
edit linuxrc with vim
unmount miniroot
pack miniroot (gzip -9)
replace miniroot.gz
umount boot.img

Thanks a lot!

I did exactly the same (of course I meant miniroot instead of initrd above), except that I used kwrite and I didn't use "9" at gzip. I'll try whether this makes a difference.

Thanks
probono

**Pasq** · 06-14-2003, 11:26 PM

We will see.

**probono** · 06-15-2003, 03:54 AM

Originally Posted by Pasq

We will see.

You won't believe it - now it works indeed! Seems as if kwrite messed up the file. Now that I was using only mcedit everything works fine

Thanks a *lot* for your help!

**Pasq** · 06-15-2003, 08:48 AM

no problem

**el_supremo** · 07-17-2004, 02:27 AM

(e.g. when it scans the different partitions for the Knoppix CD, it writes the pink lines *under* each other instead of *replacing* them /hda1 /hda2 ... etc)

This is caused by editing the file with kwrite or kate (and some other editors).
The linuxrc script creates a variable called CRE which is set to an ascii string containing a carriage return and then a code to clear the screen to the end of the current line.
This is how the script makes those lines write over each other - it precedes each output line with this CRE string.
The problem is that kwrite and kate change the carriage return to a carriage return *and* line feed. When you write out your modified file you also write out the change to the CRE string and then when you boot with that linuxrc things will look a bit strange. If you edit linuxrc with kate or kwrite and look for the line beginning with CRE, you'll see that it is actually split over two lines.
The command line editor "ed" doesn't mess up the line and apparently neither does mcedit.
I still use kate to edit linuxrc but I have written shell scripts to extract linuxrc from the minirt26.gz file and then to put it back again. The script which puts it back again uses "ed" to fix up the CRE string before it copies linuxrc back into minirt26.gz..

Best Wishes
Pete