In some cases you may want to extract the initramfs image file to check built-in contents. This post provides steps to extract initramfs image files for RHEL 7. Unlike previous version, on RHEL 7 using cpio command for the initramfs image file will not extract all files (or will give some error). For example:<\/p>\n
# ls -la \/boot\/initramfs-$(uname -r).img
\n-rw——- 1 root root 19602671 Feb 4 2016 \/boot\/initramfs-3.10.0-229.el7.x86_64.img
\n# file initramfs-3.10.0-229.el7.x86_64.img
\ninitramfs-3.10.0-229.el7.x86_64.img: gzip compressed data, from Unix, last modified: Thu Feb 4 16:02:04 2016, max compression
\n# gzip -dc initramfs-3.10.0-229.el7.x86_64.img | cpio -id — will not extract all files or will give some error
\nTo extract it on RHEL7, use skipcpio:
\n1. copy the initramfs image file to some directory.<\/p>\n
# mkdir \/tmp\/initramfs
\n# cp \/boot\/initramfs-3.10.0-229.el7.x86_64.img
\n2. extract the contents using the \/usr\/lib\/dracut\/skipcpio command :<\/p>\n
# cd \/tmp\/initramfs
\n# \/usr\/lib\/dracut\/skipcpio initramfs-3.10.0-229.el7.x86_64.img | zcat | cpio -ivd
\n.
\nvar
\nvar\/lock
\nvar\/run
\nlib
\nwhere skipcpio is the built-in tool from dracut.<\/p>\n
Listing the content of initramfs image<\/p>\n
To only list the contents of an initramfs image file, you can run lsinitrd:<\/p>\n
# lsinitrd \/boot\/initramfs-3.10.0-229.el7.x86_64.img | more
\nImage: \/boot\/initramfs-3.10.0-229.el7.x86_64.img: 19M
\n========================================================================
\nVersion: dracut-033-359.el7<\/p>\n
Arguments: -f<\/p>\n
dracut modules:
\nbash
\nnss-softokn
\ni18n
\nnetwork
\nifcfg
\ndrm
\nplymouth
\ndm
\nkernel-modules
\nlvm
\nresume
\nrootfs-block
\nterminfo
\nudev-rules
\nbiosdevname
\nsystemd
\nusrmount
\nbase
\nfs-lib
\nshutdown
\n========================================================================
\ndrwxr-xr-x 12 root root 0 May 23 10:27 .
\ncrw-r–r– 1 root root 5, 1 May 23 10:27 dev\/console
\ncrw-r–r– 1 root root 1, 11 May 23 10:27 dev\/kmsg
\ncrw-r–r– 1 root root 1, 3 May 23 10:27 dev\/null<\/p>\n","protected":false},"excerpt":{"rendered":"
In some cases you may want to extract the initramfs image file to check built-in contents. This post provides steps to extract initramfs image files for RHEL 7. Unlike previous version, on RHEL 7 using cpio command for the initramfs image file will not extract all files (or will give some error). For example:<\/p>\n
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