Karmic 9.10: cannot uncompress initrd.lz

Asked by gi-minni on 2009-11-09

Trying to uncompress initrd.lz with "unlzma -c -S .lz initrd.lz | cpio -id" always fails.
Instead I get the following error message unlzma: Decoder error.

Is this a bug? If not please advice

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Delan Azabani (azabani) said : #1

First of all, it's "/initrd.gz", not "/initrd.lz". Why are you trying to uncompress this anyway? This is an important system file for linux and is handled internally by the kernel. You shouldn't have a need to touch it.

gi-minni (minniti) said : #2

1) Karmic 9.10 use initrd.lz instead of initrd.gz
2) I need to change some casper init scripts in a live-cd context

gi-minni (minniti) said : #3

I found a solution by myself!

1) Install p7zip-full via synaptic package manager
2) Create a subdirectory to preserve the init subdirectory tree
3) Decompress initrd.lz with "7z e -so ../initrd.lz | cpio -id"

To compress it again go to the init subdirectory and execute:
4) find | cpio -o -H newc > ../newinitrd
5) go up one directory
6) 7z a -m0=lzma:a=1 initrd-mod.lz newinitrd

gi-minni (minniti) said : #4

See comment above

Colin Ian King (colin-king) said : #5

To uncompress and

gunzip < initrd.gz | cpio -i

and then to recompress I'd use:

find . | cpio -o -H newc | gzip -9 > newinitrd.gz

gi-minni (minniti) said : #6

Hi Colin,

thx for your reply. Indeed your statements are right for Jaunty not for Karmic.