ACIM Personal Knowledgebase

This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong.
====== initrd.img - View, Modify and Recreate ======

----

Question: How do I view, modify and recreate the new initrd.img on Ubuntu, Debian, CentOS, Fedora, Red-Hat, Arch Linux, or SUSE distributions?
===== View Content Of initrd.img file =====

----


initrd.img is in gzip format.
\\ So move initrd.img to initrd.gz as shown below.
<code bash>
# cp /tftpboot/el5/initrd.img  .

# ls
cdrom   initrd.img

# mv initrd.img initrd.gz


</code>
Unzip the initrd.gz file as shown below.
<code bash>
# gunzip initrd.gz

# ls
cdrom  initrd


</code>
After unziping the initrd.gz file, the initrd is further in cpio ‘newc’ format. So extract the files from initrd using cpio ‘newc’ format as shown below.
Note: info cpio will give more information about ‘newc’ format.
<code bash>
# mkdir tmp2

# cd tmp2/

# cpio -id < ../initrd
16524 blocks


</code>
Now you can view the content of initrd.img file
<code bash>
# ls
bin  dev  etc  init  modules proc  sbin  selinux  sys  tmp  var

</code>
===== Modify Content of Image and Recreate New Image =====

----


After extracting the file as shown below, make appropriate modification to any of those files. Then pack the files back into the archive using the following commands. Pack the modified files back to cpio ‘newc’ format.
# find . | cpio --create --format='newc' > /tmp/newinitrd
16524 blocks

<code bash>
# ls /tmp/
cdrom  initrd  newinitrd  tmp2

# ls -l /tmp/newinitrd
-rw-r--r-- 1 root root 8460288 Jul  2 14:50 /tmp/newinitrd

</code>
Gzip the archive file.
<code bash>
# gzip newinitrd

# ls
cdrom  initrd  newinitrd.gz  tmp2

# ls -l newinitrd.gz
-rw-r--r--  1 root root 6649867 Jul  2 14:50 newinitrd.gz

</code>
Move file as an image file. You can use the newinitrd.img as your new boot image.
<code bash>
# mv newinitrd.gz newinitrd.img

# ls -l newinitrd.img
-rw-r--r-- 1 root root 6649867 Jul  2 14:50 newinitrd.img

</code>
ACIM Personal Knowledgebase

User Tools

Site Tools

Page Tools
