uptime -s changing reported time












0















I have a script that relies in time Ubuntu 18.04 is started found by:



uptime -s


I save that value in a file when I run the script. I noticed when I started Ubuntu that time was:



uptime -s
2019-01-07 18:01:59


After running for a bit more than two hours, same command reports now a different time (I remained logged in same account all this time):



uptime -s
2019-01-07 18:01:58


I would expect the command reports same time within same login session. But somehow time changes with 1 second (it is earlier now).



Is this an OS or tool issue?



https://elixir.bootlin.com/linux/latest/source/fs/proc/uptime.c
struct timespec64 uptime;
ktime_get_boottime_ts64(&uptime);


How can I get system up time without such fluctuation?



Update:



I though I found the answer in: Linux: Getting date & time of system startup



But I was wrong, it just luck, after running a few more tests, one can see it is OS problem, the time rotates between 58 and 59 depending on nanoseconds:



$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.670091767
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.627339874
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.708332394
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.821526069
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.604129974
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.469767199
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:59.264900963
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.986611962
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.851955874
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.958194732
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:59.066728481


I seems, there is no reliable system uptime to second level.










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  • Possible duplicate of Linux: Getting date & time of system startup

    – bummi
    Jan 7 at 19:30
















0















I have a script that relies in time Ubuntu 18.04 is started found by:



uptime -s


I save that value in a file when I run the script. I noticed when I started Ubuntu that time was:



uptime -s
2019-01-07 18:01:59


After running for a bit more than two hours, same command reports now a different time (I remained logged in same account all this time):



uptime -s
2019-01-07 18:01:58


I would expect the command reports same time within same login session. But somehow time changes with 1 second (it is earlier now).



Is this an OS or tool issue?



https://elixir.bootlin.com/linux/latest/source/fs/proc/uptime.c
struct timespec64 uptime;
ktime_get_boottime_ts64(&uptime);


How can I get system up time without such fluctuation?



Update:



I though I found the answer in: Linux: Getting date & time of system startup



But I was wrong, it just luck, after running a few more tests, one can see it is OS problem, the time rotates between 58 and 59 depending on nanoseconds:



$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.670091767
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.627339874
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.708332394
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.821526069
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.604129974
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.469767199
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:59.264900963
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.986611962
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.851955874
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.958194732
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:59.066728481


I seems, there is no reliable system uptime to second level.










share|improve this question









New contributor




ppp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





















  • Possible duplicate of Linux: Getting date & time of system startup

    – bummi
    Jan 7 at 19:30














0












0








0








I have a script that relies in time Ubuntu 18.04 is started found by:



uptime -s


I save that value in a file when I run the script. I noticed when I started Ubuntu that time was:



uptime -s
2019-01-07 18:01:59


After running for a bit more than two hours, same command reports now a different time (I remained logged in same account all this time):



uptime -s
2019-01-07 18:01:58


I would expect the command reports same time within same login session. But somehow time changes with 1 second (it is earlier now).



Is this an OS or tool issue?



https://elixir.bootlin.com/linux/latest/source/fs/proc/uptime.c
struct timespec64 uptime;
ktime_get_boottime_ts64(&uptime);


How can I get system up time without such fluctuation?



Update:



I though I found the answer in: Linux: Getting date & time of system startup



But I was wrong, it just luck, after running a few more tests, one can see it is OS problem, the time rotates between 58 and 59 depending on nanoseconds:



$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.670091767
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.627339874
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.708332394
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.821526069
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.604129974
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.469767199
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:59.264900963
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.986611962
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.851955874
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.958194732
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:59.066728481


I seems, there is no reliable system uptime to second level.










share|improve this question









New contributor




ppp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












I have a script that relies in time Ubuntu 18.04 is started found by:



uptime -s


I save that value in a file when I run the script. I noticed when I started Ubuntu that time was:



uptime -s
2019-01-07 18:01:59


After running for a bit more than two hours, same command reports now a different time (I remained logged in same account all this time):



uptime -s
2019-01-07 18:01:58


I would expect the command reports same time within same login session. But somehow time changes with 1 second (it is earlier now).



Is this an OS or tool issue?



https://elixir.bootlin.com/linux/latest/source/fs/proc/uptime.c
struct timespec64 uptime;
ktime_get_boottime_ts64(&uptime);


How can I get system up time without such fluctuation?



Update:



I though I found the answer in: Linux: Getting date & time of system startup



But I was wrong, it just luck, after running a few more tests, one can see it is OS problem, the time rotates between 58 and 59 depending on nanoseconds:



$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.670091767
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.627339874
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.708332394
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.821526069
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.604129974
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.469767199
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:59.264900963
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.986611962
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.851955874
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:58.958194732
$ date -d "`cut -f1 -d. /proc/uptime` seconds ago" +"%F %T.%N"
2019-01-07 18:01:59.066728481


I seems, there is no reliable system uptime to second level.







linux ubuntu






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edited Jan 7 at 19:46







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asked Jan 7 at 19:21









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  • Possible duplicate of Linux: Getting date & time of system startup

    – bummi
    Jan 7 at 19:30



















  • Possible duplicate of Linux: Getting date & time of system startup

    – bummi
    Jan 7 at 19:30

















Possible duplicate of Linux: Getting date & time of system startup

– bummi
Jan 7 at 19:30





Possible duplicate of Linux: Getting date & time of system startup

– bummi
Jan 7 at 19:30










1 Answer
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oldest

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0














Found an answer here:



Linux: Getting date & time of system startup



This command seems to give correct result, unlike uptime -s



 date -d "`cut -f1 -d. /proc/uptime` seconds ago"


Example:



date -d "`cut -f1 -d. /proc/uptime` seconds ago"
Mo 7. Jan 18:01:59 CET 2019


It seems uptime -s is not reliable.






share|improve this answer








New contributor




ppp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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    1 Answer
    1






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    active

    oldest

    votes






    active

    oldest

    votes









    0














    Found an answer here:



    Linux: Getting date & time of system startup



    This command seems to give correct result, unlike uptime -s



     date -d "`cut -f1 -d. /proc/uptime` seconds ago"


    Example:



    date -d "`cut -f1 -d. /proc/uptime` seconds ago"
    Mo 7. Jan 18:01:59 CET 2019


    It seems uptime -s is not reliable.






    share|improve this answer








    New contributor




    ppp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.

























      0














      Found an answer here:



      Linux: Getting date & time of system startup



      This command seems to give correct result, unlike uptime -s



       date -d "`cut -f1 -d. /proc/uptime` seconds ago"


      Example:



      date -d "`cut -f1 -d. /proc/uptime` seconds ago"
      Mo 7. Jan 18:01:59 CET 2019


      It seems uptime -s is not reliable.






      share|improve this answer








      New contributor




      ppp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.























        0












        0








        0







        Found an answer here:



        Linux: Getting date & time of system startup



        This command seems to give correct result, unlike uptime -s



         date -d "`cut -f1 -d. /proc/uptime` seconds ago"


        Example:



        date -d "`cut -f1 -d. /proc/uptime` seconds ago"
        Mo 7. Jan 18:01:59 CET 2019


        It seems uptime -s is not reliable.






        share|improve this answer








        New contributor




        ppp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
        Check out our Code of Conduct.










        Found an answer here:



        Linux: Getting date & time of system startup



        This command seems to give correct result, unlike uptime -s



         date -d "`cut -f1 -d. /proc/uptime` seconds ago"


        Example:



        date -d "`cut -f1 -d. /proc/uptime` seconds ago"
        Mo 7. Jan 18:01:59 CET 2019


        It seems uptime -s is not reliable.







        share|improve this answer








        New contributor




        ppp is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
        Check out our Code of Conduct.









        share|improve this answer



        share|improve this answer






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        answered Jan 7 at 19:27









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