BASH scripting question

[RedWagon]

I'm trying to format the output of uptime from

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 10:34:34 up 3 days,  1:02, load average: 0.00, 0.00, 0.00

to

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3 days,  1:02

by cutting everything before "up " and everything after ", load" in bash.

[antonone]

I've a different suggestion. `uptime` gives different output depending on the locale on a specified system. This can be problematic to parse sometimes (if you want to share this script over different installations of Linux). It's easier to depend on `/proc/uptime` contents.

The /proc/uptime file contains two values separated by a space - the first one is most important, as it's a number of seconds since boot time. You can read this value, perform some calculations on it to extract the day, hour, minute and second of the system uptime. I've included an example of how you may do it:

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time=`cat /proc/uptime | cut -d. -f1`

days=$((time/60/60/24))
hour=$((time/60/60))
minute=$((time/60%60))
second=$((time%60))

# if $days are [g]reater [t]han ("gt") zero, then:
if [ $days -gt 0 ]; then
    echo -n "$days days "
fi  

# write rest of data
printf "%02d:%02d:%02d\n" $hour $minute $second

This script will display a string like:

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$ ./bash-script.sh 
01:46:09

and that's the same value uptime will give:

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$ uptime
 17:04:32 up  1:46,  2 users,  load average: 0.01, 0.03, 0.00

[RedWagon]

Thanks antonone, that works great. There was a small mistake though, the hours line should look like this:

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hour=$((time/60/60%24))

otherwise it shows total hours and not just hours for that day.

[antonone]

Of course you're right. Glad it helped ;).