update-initramfs command not found

Question

How can I update initramfs somewhat how it is described elsewhere for adding firmware?

For a Debian 10 I get a command not found error. initramfs-tools is installed.

root@pc:/home/.../linux-firmware/i915# update-initramfs -u
bash: update-initramfs: command not found
root@pc:/home/.../linux-firmware/i915# apt install initramfs-tools
Reading package lists... Done
Building dependency tree       
Reading state information... Done
initramfs-tools is already the newest version (0.133).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

---

Ok, googled again and found package live-tools with live-update-initramfs. However, now other failure.

root@pc:/home/stefan/Downloads/intel-firmware/linux-firmware/i915# apt install live-tools
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Suggested packages:
  debian-installer-launcher rsync uuid-runtime
The following NEW packages will be installed:
  live-tools
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 31.1 kB of archives.
After this operation, 109 kB of additional disk space will be used.
Get:1 http://deb.debian.org/debian buster/main amd64 live-tools all 1:20171207 [31.1 kB]
Fetched 31.1 kB in 0s (91.4 kB/s)   
Selecting previously unselected package live-tools.
(Reading database ... 160376 files and directories currently installed.)
Preparing to unpack .../live-tools_1%3a20171207_all.deb ...
Unpacking live-tools (1:20171207) ...
Setting up live-tools (1:20171207) ...
Created symlink /etc/systemd/system/multi-user.target.wants/live-tools.service → /lib/systemd/system/live-tools.service.
update-rc.d: warning: start and stop actions are no longer supported; falling back to defaults
update-rc.d: warning: start runlevel arguments (none) do not match live-tools Default-Start values (S)
Processing triggers for man-db (2.8.5-2) ...
Processing triggers for systemd (241-5) ...
root@pd:/home/stefan/Downloads/intel-firmware/linux-firmware/i915# live-update-initramfs -u
update-initramfs: Generating /boot/initrd.img-4.19.0-5-amd64
/usr/sbin/update-initramfs.orig.initramfs-tools: 157: /usr/sbin/update-initramfs.orig.initramfs-tools: mkinitramfs: not found
update-initramfs: failed for /boot/initrd.img-4.19.0-5-amd64 with 127.

Answer 1

Found update-initramfs in sbin. I do not understand why it is not in my root PATH. However,

# sudo update-initramfs -u
update-initramfs: Generating /boot/initrd.img-4.19.0-5-amd64

did the job.

Answer 2

Had the same error when using su command to enter root

Solved by adding /sbin to PATH once entered root on terminal:

# su
# export PATH=/sbin:$PATH