Linux-kernel mailing list archive 1999-22,: Re: How can Emacs get a unique ID per Linux reboot?

# Re: How can Emacs get a unique ID per Linux reboot?

Paul Eggert (eggert@twinsun.com)
Mon, 31 May 1999 22:51:31 -0700 (PDT)

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Date: Tue, 1 Jun 1999 05:03:17 +0100 (GMT)
From: Riley Williams <rhw@memalpha.cx>

echo $[`date +%s`-`tr ' ' . < /proc/uptime | cut -d . -f 1`]

...as, at least on my system, that returns a constant value.

On my system, /proc/uptime is unaffected when I change the clock,
which means that subtracting the uptime from the current time is not
reliable. E.g. see the transcript below, which demonstrates that
current_time - uptime == btime. Hencie neither suffices for a unique
ID per reboot. (I think btime is broken whereas uptime is OK.)

# echo $[`date +%s`-`tr ' ' . < /proc/uptime | cut -d . -f 1`]
927768214
# grep btime /proc/stat
btime 927768214
# date 05312240
Mon May 31 22:40:00 PDT 1999
# echo $[`date +%s`-`tr ' ' . < /proc/uptime | cut -d . -f 1`]
927767974
# grep btime /proc/stat
btime 927767974
# uname -a
Linux gal 2.0.36 #1 Wed May 12 14:28:16 PDT 1999 i686 unknown

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- Next message: Gregory Maxwell: "Re: Migrating to larger numbers"
- Previous message: Dan Koren: "Re: Buffer Cache API"
- Maybe in reply to: Paul Eggert: "How can Emacs get a unique ID per Linux reboot?"
- Next in thread: Riley Williams: "Re: How can Emacs get a unique ID per Linux reboot?"
- Reply: Riley Williams: "Re: How can Emacs get a unique ID per Linux reboot?"