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Adrian George
Asked: 2013-08-22 14:42:53 +0800 CST

How to display time elapsed since last system boot using "uptime"?

  • 772

I want to display the time elapsed since last system boot using uptime, but I don't want it to display all that info. I just want to know how many hours passed since last system boot (i.e. : 18:17:59)

command-line

10 Answers

  1. Best Answer

    To get the time elapsed since last system boot in hh:mm:ss format, you can use:

    awk '{print int($1/3600)":"int(($1%3600)/60)":"int($1%60)}' /proc/uptime

    /proc/uptime pseudo-file contains two numbers:

    • The first number is how long the system has been up in seconds.
    • The second number is how much of that time the machine has spent idle in seconds.

    So, using awk you can take firs number and convert it in hh:mm:ss format.

    • 42

  2. To get uptime in seconds:

    awk '{print $1}' /proc/uptime

    To get uptime in minutes:

     echo $(awk '{print $1}' /proc/uptime) / 60 | bc

    To get uptime in hours:

     echo $(awk '{print $1}' /proc/uptime) / 3600 | bc

    To get x digits of precision you can add scale=x, e.g. for x=2

    echo "scale=2; $(awk '{print $1}' /proc/uptime) / 3600" | bc
    • 22

  3. Try this one:

    uptime | awk '{ print $3 }'

    In fact, it prints the third word of the line produced by uptime.

    • 3

  4. A trivial modification to show days:

    awk '{print int($1/86400)"days "int($1%86400/3600)":"int(($1%3600)/60)":"int($1%60)}' /proc/uptime
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  5. figured I'd add mine to the collection since there's nothing similar...
    tried to be more efficient with mine:

    awk '{m=$1/60; h=m/60; printf "%sd %sh %sm %ss", int(h/24), int(h%24), int(m%60), int($1%60) }' /proc/uptime

    result: 42d 17h 23m 55s

    EDIT: since I realized I didn't quite answer the original question, here's a revision specifically for that:

    awk '{m=$1/60; h=m/60; printf "%s:%s:%s", int(h%24), int(m%60), int($1%60) }' /proc/uptime

    result: 17:23:55

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  6. This will format your output as 2 zero padding:

    awk '{printf("%02d:%02d:%02d",int($1/3600),int($1/3600/60),int($1%60))}' /proc/uptime
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  7. As an addition to @realmoonstruck answer:

    You could do this solely in awk which saves you one pipe and the subsequent call of bc.

    To get the uptime in minutes:

    awk '{print int($1)/60}' /proc/uptime
    • 1

  8. For simple metrics, I sometimes just want an INT of the hours:

    #!/usr/bin/env -eux
upsince=$(date +%s -d "$(uptime -s)");
now=$(date +%s);
DIFF=$((now-upsince));
scale=2;

echo $((DIFF / 3600)))

    NOTE: You could '+ 1' to round up to the nearest full hour

    • 0

  9. A further trivial modification for layout:

    UPTIME_STR=$(awk '{print int($1/86400)"d "int($1%86400/3600)"h "int(($1%3600)/60)"m "int($1%60)"s"}' /proc/uptime)
echo "['$(date)'] Device Uptime:" $UPTIME_STR

    Example Output:

    ['Mon Jan 17 22:41:32 SAST 2022'] Device Uptime: 0d 0h 10m 58s

    • 0 
  10. awk '{printf( "%04d:%02d:%02d:%02d\n",int($1/86400) , int(($1%86400)/3600) , int(($1%3600)/60) , int($1%60)  )}'  /proc/uptime;

    Format [dddd:hh:mm:ss]
    Sample: 0122:05:14:03

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