Viewing the contents of an initrd image
I was doing some research tonight, and needed to look inside my initrd image to see if a couple of device drivers were present. Initrd images are stored as compressed cpio archives, which allows a pipeline like the following to be used to extract the contents of an image:
$ gunzip < initrd-2.6.29.4-167.fc11.x86_64.img | cpio -i --make-directories
14050 blocks
Once extracted, you can use cd and cat to view the files and directories that are part of the image:
$ ls -l
drwxrwxrwt. 11 root root 4096 2009-07-14 23:30 . drwxr-xr-x. 23 root root 4096 2009-07-07 14:55 .. drwx------ 2 root root 4096 2009-07-14 23:30 bin drwx------ 3 root root 4096 2009-07-14 23:30 dev drwx------ 4 root root 4096 2009-07-14 23:30 etc -rwx------ 1 root root 1938 2009-07-14 23:30 init -rw------- 1 root root 3428816 2009-07-14 23:29 initrd-2.6.29.4-167.fc11.x86_64.img drwx------ 6 root root 4096 2009-07-14 23:30 lib drwx------ 2 root root 4096 2009-07-14 23:30 lib64 drwx------ 2 root root 4096 2009-07-14 23:30 proc lrwxrwxrwx 1 root root 3 2009-07-14 23:30 sbin -> bin drwx------ 2 root root 4096 2009-07-14 23:30 sys drwx------ 2 root root 4096 2009-07-14 23:30 sysroot drwx------ 4 root root 4096 2009-07-14 23:30 usr
$ ls -l etc
total 20 -rw-r--r-- 1 root root 29 2009-07-14 23:30 fedora-release -rw-r--r-- 1 root root 1976 2009-07-14 23:30 ld.so.cache -rw-r--r-- 1 root root 28 2009-07-14 23:30 ld.so.conf drwx------ 2 root root 4096 2009-07-14 23:30 ld.so.conf.d drwx------ 2 root root 4096 2009-07-14 23:30 sysconfig lrwxrwxrwx 1 root root 14 2009-07-14 23:30 system-release -> fedora-release
Alex on July 22nd, 2009
Howdy,
Another hot tip is that FreeBSD’s tar(1) aka ‘bsdtar’ car extract and view cpio files e.g
#tar -tvf /var/tmp/initrd-2.6.23.12-52.fc7.img | head -5
-rwx—— 1 0 0 2418 Jan 30 2008 init
drwx—— 3 0 0 0 Jan 30 2008 etc
-rw-r–r– 1 0 0 28 Jul 8 2007 etc/ld.so.conf
drwx—— 2 0 0 0 Jan 30 2008 etc/ld.so.conf.d
-rw-r–r– 1 0 0 73 Apr 26 2007 etc/ld.so.conf.d/opensync-32.conf
– Alex