Linux ls command timestamps in microseconds is easy-ish

Any of the following work

ls -la --time-style=full-iso ...
ls --full-time ...

Which gave me

-rw-r--r-- 1 root root 1534 2023-01-01 16:46:58.394054373 +0000 group

Where the format is

The TIME_STYLE argument can be full-iso, long-iso, iso, locale, or +FORMAT. FORMAT is interpreted like in date(1).

But during installing/removing a package it touched the file, and I have

-rw-r--r-- 1 root root 3784 2022-12-30 11:14:15.436236905 +0000 passwd
-rw-r--r-- 1 root root 3764 2022-12-30 11:14:15.000000000 +0000 passwd-
and 
-rw-r--r-- 1 root root 1534 2023-01-01 16:46:58.394054373 +0000 group
-rw-r--r-- 1 root root 1523 2022-12-30 11:14:15.000000000 +0000 group-

so the temporary files have .000000 microseconds – so there is something else going on!

You can use

alias lt=’ls -ltr –full-time –color=auto’

to make a command “lt” which is the ls command, plus options.