I want a linux command that will return a unique identifier that would be generated at boot time

Thoughts & Feedback
#1

Hi
I am aware of the UUID and uname but there is no unique identifier for every time a system boots up.
There are security reasons why I want this.
The command should include the UUID, the kernel(uname) and a random identifier of boot.
I presume this should only be run by root.
I can do this myself with a bit of work but thought it should be part of linux.
I did not want to bother Linus

#2

Try this:

date +"%s"

It will display the seconds since the epoch. Guaranteed different on every boot.
This , together with a unique hardware ID like primary NIC MAC will make it truely unique.

You can even extend it to nanoseconds (a bit overkill for this case though):

date +"%s%N"
  1. Are you sure you want the UUID of the drive that is mounted as rootfs ?
  2. With 'uname' you mean 'uname -r' ?

Hmm, okay .... In that case, try this:

echo "$( { lsblk -no UUID "$( df |grep '/$' |cut -d\  -f1 )" ; uname -r ; date +"%s" ;} | tr -d "\n" )"

Don't expect exceptionally rare usecases to be implemented as a standard command in any OS.

The good thing of the Linux (POSIX) shells is that in these exceptional cases a oneliner can save the day :slight_smile:

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#3

do you really believe Linus T. would reply? As @tkn mentioned, this is an extreme use case.

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#4

I will let you cogitate as to the reasons why I would want such information and its uses.
The UUID is relatively constant as is the kernel in time. The solution given by @tkn above is quite neat but very variable and not system resident unless saved to disk or emailed out.
I imagine when Linus first thought of Linux people could have said "this is an extreme use case"
Let one not be limited by the imagination of others

#5

you need to generate entropy to your linux system, here's a link

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