I have several Linux distributions installed on my PC (13 at last count) and I would like to know how I can find when I last booted each of them. Preferably as a list, like on one line when I last booted my Debian installation, one another line when I last booted my Gentoo install, on another line when I last booted my PCLinuxOS install, etc. I suppose I can check when the last edit to their files was made (as a way of testing when they were last started) but as I chroot into them regularly to update them (using their package manager) I thought this may not be an accurate way of checking.

  • 1
    last /the/chroot/var/log/wtmp perhaps? there may be a reboot line in there
    – thrig
    Commented Jan 5, 2018 at 3:10
  • Gives me a ridiculous time for my Arch and Gentoo system. I booted them less than an hour ago yet they're giving me the exact same output for that command wtmp begins Sun Dec 17 19:28:53 2017.
    – Josh Pinto
    Commented Jan 5, 2018 at 3:30
  • wtmp tells you about logins, not boot time. /bar/log/syslog or /var/log/kernel might be more useful. Looking at the modification time might be enough.
    – mc0e
    Commented Jan 5, 2018 at 5:54
  • Sorry mate but unfortunately neither file you mentioned exists (and yes after correcting for your bar typo) for any of my installed systems.
    – Josh Pinto
    Commented Jan 5, 2018 at 6:19
  • on installed systems you can use who -b or w to know how long & when system is marked "up & running" but this will not inform you on boot request time
    – francois P
    Commented Jan 5, 2018 at 7:29

1 Answer 1


It's a sure thing that each instance wrote more than one line of dmesg / syslog to /var/log/* files at boot time. Filenames like messages and syslog are pretty popular, but YMWV. Mount the relevant partition RO, and go grep'ing for "kernel:" bootup messages. As a bonus, the syslog output will reveal the configured uname hostname of each instance. Looking for the string "Linux version" would be a good starting point, as it tends to appear early in the boot sequence.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .