apt-get autoremove takes quadratically long

[Tom Womack]

apt-get autoremove regenerates the initrd after removing each kernel. Since you generally call this command only when your boot volume is full of old kernels, it seems sub-optimal to regenerate the initrd eight times when removing eight kernels. Could something be done with triggers to do a single regeneration of the initrd at the end?

This is in 14.04

[Jarno Suni (jarnos)]

I think this script runs update-grub after every remove of kernel: /etc/kernel/postinst.d/zz-update-grub. Would it be possible to use an environment variable that makes it possible to skip that post-installation script, and run update-grub manually after last removal, if wanted?

[Jarno Suni (jarnos)]

Oh, you can do something now: you can set update-grub executable (found by command `which update-grub`) not executable by `sudo chmod -x` temporarily, and then remove the kernels, and then restore the state of the file by `sudo chmod +x` and finally run `sudo update-grub` manually. This is because /etc/kernel/postinst.d/zz-update-grub exits, if the executable is not found (at least in 14.04 and 16.04).

[Jarno Suni (jarnos)]

Oh, this is the script that is used for updating grub in conjunction with kernel removal: /etc/kernel/postrm.d/zz-update-grub
Anyway, OP meant regenerating the initrd, which is handled by initramfs-tools scripts.

[Jarno Suni (jarnos)]

The aforementioned `sudo chmod -x` command has the side-effect that update-grub will be left non-executable in case of power cut.