Packing and unpacking initrd: Difference between revisions

To modify initird.img or other similar images, first determine the compression method used by the initrd file. Below, we see that it's using gzip which is typical.

# file initrd.img
initramfs.gz: gzip compressed data, last modified: Thu Jul 22 04:16:52 2021, max compression, from Unix, original size 46489600

To unpack and extract initird.img, compressed with gzip:

## Go to an empty directory before extracting the image.
# mkdir -p /mnt/initrd_extract && cd /mnt/initrd_extract
# gzip -dc < /path/to/initrd.img | cpio -i

To re-pack files back into initrd.img after making your changes:

# Go to the directory containing the contents of the image.
# cd /mnt/initrd_extract
# find . | cpio -o -c | gzip -9 > /path/to/initrd.img

v t e Linux

Various Linux Notes	/etc/fstab Access.conf ACL Apache Proxy to Internal Server APM X-C1 (Mustang) ARP Authselect Bash Scripting Blockparser Booting Linux without a Graphics Card Building Container Images Burning CD/DVD in Linux Clear RAID Signatures on Linux Cobbler Colorized Terminal Outputs Compiling MIPS Configure Sendmail CPanel CPanel Fork Bomb Protection CPU Frequency Scaling Create a Linux User with an Empty Password Cron and PAM Issues Dell OpenManage Diff Two Command Outputs DirectAdmin Disable Filesystem Check on Startup DNS Ad Blocker Driver Disk Drop caches End / Home keys don't work in Terminal Entropy in the Linux Kernel Entropy Source using RTL-SDR Exit Codes Extract .exe Resources with dd File Attributes Fixing ixgbe unsupported SFP+ module type was detected Get Active Linux Virtual Console Getting Hardware UUID Hosts.deny How to change Linux desktop user directories How to hot-swap SATA disks on Linux HP Smart Storage Administrator Hyper-threading IBM Spectrum Archive IBM Spectrum Protect IBM Tape IBM Tape Diagnostic Tool InterWorx Kerberize NFS Kerberize SSH Linux Clustering Linux Fonts Linux Namespaces Linux Network Interface Naming Linux Nvidia Driver Linux Process Accounting Linux Uptime in Seconds Linux UTF-8 Font Mainline Kernel on CentOS 7 Missing Fonts Mod fastcgi Install on Apache 2 / cPanel Mod fcgid Monitoring network traffic in Linux Mounting / Unmounting KVM Image Mounting Samba (CIFS) shares Multiple Networks on Linux MySQL Database with Hash Sign No Console Output Number of Files Opened Open OnDemand Packing and unpacking initrd PAM Issues Partition Alignment Patching a binary file with dd Perl Module Location Raspberry Pi Red Hat kickstart Red Hat to Debian Reverse SSH Tunnel Ruby on Rails under cPanel Rutorrent + rtorrent Installation Guide on CentOS 6.4 Self Signed SSL Certificates Service Management Sick Beard StartSSL Free Certificate Symlink Taking a Screenshot in X11 Timezone Tor TOR Transparent Proxy Traefik Troubleshooting a Slow Linux System Turning on swap with a page file Udev Rules Verify SSL Certificate matches Private Key VMware Workstation Webcam X Display Manipulation X Forwarding

Linux Tools and Utilites	Anaconda Ansible Aria2 Autofs Awk Badblocks Bash Shell Binwalk Bosh Ceph Chntpw Chrony Clonezilla Cloud-init CloudStack Column Cron Curl Cvs2git Date Dbus Dd Dm-crypt Dovecot DRBD ElasticSearch Enroot Environment Module Envsubst Fail2ban FFmpeg Find Firecracker Flashrom Foreman FortiClient Fswebcam Galaxy Git Gnome Gobetween GPFS Grafana Grub Hdparm Home Assistant How to disable SELinux Htaccess Infiniband InfluxDB InfluxDB 1.x Insert a kickstart file into a iso image Inspircd IOzone Iperf3 Ipmitool Irqbalance John The Ripper Lightdm Lm sensors Logrotate LSF LVM Lynx Mailx Md5sum Mdadm Midnight Commander Motion Mount Mutt Nomad OpenLDAP Openocd OpenSSL OpenVPN Packer PHP Pi-hole Postgres PowerBroker Identity Service Proxmox Pueue PulseAudio Puppet Quota Red Hat Satellite Restic Rsync Rtorrent Ruby Sabnzbd Sage Samba Screen Sed SELinux Sendmail Shell Configs Singularity Sleep Slurm SMART Sonarr Sqlite SquashFS Squid SSH Steam Stoken Strace Sudo Sync Sysctl Syslog Sysrq System Security Services Daemon (SSSD) Systemd Tar Tcsh Telegraf Terraform Thttpd Tmux Tomcat Top Umask Unix2dos Vim Virsh Virt-customize VirtualBox VirtualGL Visidata Vnstat Weechat Wget XFS Youtube-dl ZFS Zram

Package Management	APT Pacman RPM Yum

Linux Distributions	Alpine Linux Arch Linux CentOS Fedora NixOS Red Hat Enterprise Linux Tails Tiny Core Linux Ubuntu

Networking	Blazemeter CSF/LFD Exim Firewall FreeIPA Get DHCP Network Settings IP Aliasing Ipset IPTables IPv6 IPXE Link Aggregation Linux Network Namespaces MTU Net-tools to iproute2 Netcat Open vSwitch OpenWRT Postfix Raspberry Pi Torified Wifi Socat Static Routes StrongSwan Tcpdump Traffic Forwarder using IPTables Wi-Fi WireGuard

Containers	Docker Docker Compose Docker Swarm Helm K3s Kibana Kubernetes Mailu PKS Podman

@@ Line 1: / Line 1: @@
-modify {{code|initird.img}} or other similar images
+To modify {{code|initird.img}} or other similar images, first determine the compression method used by the initrd file. Below, we see that it's using gzip which is typical.
-To extract {{code|initird.img}}:
+{{Highlight
-<syntaxhighlight lang="bash" line start="1" enclose="div">
+| code = # file initrd.img
- # Go to an empty directory before extracting the image.
+initramfs.gz: gzip compressed data, last modified: Thu Jul 22 04:16:52 2021, max compression, from Unix, original size 46489600
- mkdir -p /mnt/initrd_extract && cd /mnt/initrd_extract
+| lang = terminal
- gzip -dc < /path/to/initrd.img | cpio -i
+}}
-</syntaxhighlight>
-To pack files back into {{code|initrd.img}}
+To unpack and extract {{code|initird.img}}, compressed with gzip:
-<syntaxhighlight lang="bash" line start="1" enclose="div">
- # Go to the directory containing the contents of the image.
- cd /mnt/initrd_extract
- find . | cpio -o -c | gzip -9 > /path/to/initrd.img
-</syntaxhighlight>
-You may want to run {{code|file /path/to/initrd.img}} in order to determine the exact method of compression. The above commands above assumes {{code|cpio + gzip}}.
+{{Highlight
+| code = ## Go to an empty directory before extracting the image.
+# mkdir -p /mnt/initrd_extract && cd /mnt/initrd_extract
+# gzip -dc < /path/to/initrd.img {{!}} cpio -i
+| lang = terminal
+}}
+To re-pack files back into {{code|initrd.img}} after making your changes:
-{{Navbox Linux}}[[Category:Linux]]
+{{Highlight
+| code = # Go to the directory containing the contents of the image.
+# cd /mnt/initrd_extract
+# find . {{!}} cpio -o -c {{!}} gzip -9 > /path/to/initrd.img
+| lang = terminal
+}}<br />
+{{Navbox Linux}}
+[[Category:Linux]]

Packing and unpacking initrd: Difference between revisions

Revision as of 17:36, 9 August 2021

Recent Changes

Recent Changes under Linux

Recent Changes under Guides

Ad-Free + Tracker-Free