LinuxQuestions.org - [SOLVED] time difference calculation

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rakrr786

04-24-2013 05:02 AM

time difference calculation

Hi i am trying to calculate the difference between 2 time stamps but unable to sort out hw to do it.

my time format is like 05:36:11 (24 hr clock) can anyone suggest a method or utility so i can calculate a time diff in shell script.

kareempharmacist

04-24-2013 05:27 AM

more details please.. is it a bash script?
did you read about zsh which is more powerful?
I think your problem is about data types ..may be converting it to another format will be helpful..
asking this question in the right forum will help you a lot which is the "Programming forum"..

rakrr786

04-24-2013 05:35 AM

sorry for posting here

yes it is a bash script
no i havenot looked in zsh

yup i m converting the format to seconds.

TenTenths

04-24-2013 05:51 AM

The following should give you some clues:

Code:

#!/bin/bash



# Time Arithmetic



TIME1=05:36:11

TIME2=06:46:00



# Convert the times to seconds from the Epoch

SEC1=`date +%s -d ${TIME1}`

SEC2=`date +%s -d ${TIME2}`



# Use expr to do the math, let's say TIME1 was the start and TIME2 was the finish

DIFFSEC=`expr ${SEC2} - ${SEC1}`



echo Start ${TIME1}

echo Finish ${TIME2}



echo Took ${DIFFSEC} seconds.



# And use date to convert the seconds back to something more meaningful

echo Took `date +%H:%M:%S -ud @${DIFFSEC}`

This gives the output:

Code:

Start 05:36:11

Finish 06:46:00

Took 4189 seconds.

Took 01:09:49

Enjoy!

rakrr786

04-24-2013 07:08 AM

thanks karim and tentenths

was stuck at converting seconds to hh:mm:ss format

David the H.

04-25-2013 12:56 PM

You might be interested in these advanced date processing utilities, including ddiff, which does just what you're asking.

http://www.fresse.org/dateutils/

rakrr786

04-25-2013 11:49 PM

I dont think i will get those utilities even though it does exactly what i need

any how i figured out the arithmetics as below

Quote:

hrs1=3600
hrs2=60

SEC1=`date -d "${starttime}" +%s` ##in hh:mm:ss formant to convert in seconds from epoch time
SEC2=`date -d "${endtime}" +%s`
difftemp=`expr "${SEC2}" - "${SEC1}"`
let hh=$difftemp/$hrs1
let mm=$difftemp/$hrs2
let ss=$difftemp-$mm\*$hrs2
totaldiff=`echo "$hh":"$mm":"$ss"`

thanks for ur help and i dont know hw to give reputation and cant see a white scale either

TenTenths

04-26-2013 02:21 AM

Quote:

Originally Posted by rakrr786 (Post 4939057)

any how i figured out the arithmetics as below

Just curious, was there any particular reason for doing all the arithmetic, multiplications and divisions instead of just:

Code:

SEC1=`date -d "${starttime}" +%s` ##in hh:mm:ss formant to convert in seconds from epoch time

SEC2=`date -d "${endtime}" +%s`

difftemp=`expr "${SEC2}" - "${SEC1}"`

totaldiff=`date +%H:%M:%S -ud @${difftemp}`

rakrr786

04-26-2013 03:29 AM

yup

totaldiff=`date +%H:%M:%S -ud @${difftemp}`

was giving blank data in totaldiff variable and i can't find why

rakrr786

04-26-2013 03:32 AM

also i have one more thing
tempapp.txt
06:32:33

awk -F : '{ hours = 3600*$1 }{ minutes = 60*$2 }{ seconds = $3 }{SEC1 = hours+minutes+seconds} END { print SEC1 }' tempapp.txt
23553

gives proper output but i cannot use SEC1 once i come out of awk and also cannot assign the output to any other variable i assigned it gives null value

TenTenths

04-26-2013 03:32 AM

Quote:

Originally Posted by rakrr786 (Post 4939147)

yup

totaldiff=`date +%H:%M:%S -ud @${difftemp}`

was giving blank data in totaldiff variable and i can't find why

AH, ok, worked fine on my servers: GNU bash, version 3.2.25(1)-release (x86_64-redhat-linux-gnu)

Anyways, was just curious, good you got sorted.

rakrr786

04-26-2013 03:36 AM

any idea about the awk command

TenTenths

04-26-2013 03:45 AM

Variables created inside AWK programs aren't exposed to the bash shell, you can however assign the output of AWK to a variable:

Code:

#!/bin/bash



SEC1=`awk -F : '{ hours = 3600*$1 }{ minutes = 60*$2 }{ seconds = $3 }{SEC1 = hours+minutes+seconds} END { print SEC1 }' tempapp.txt`



echo ${SEC1}

mimeini

05-27-2021 09:36 AM

Thanks to TenTenth

Thanks to TenTenth for this replay. I think that is a cool solution and just what i need.

#!/bin/bash

# Time Arithmetic

TIME1=05:36:11
TIME2=06:46:00

# Convert the times to seconds from the Epoch
SEC1=`date +%s -d ${TIME1}`
SEC2=`date +%s -d ${TIME2}`

# Use expr to do the math, let's say TIME1 was the start and TIME2 was the finish
DIFFSEC=`expr ${SEC2} - ${SEC1}`

echo Start ${TIME1}
echo Finish ${TIME2}

echo Took ${DIFFSEC} seconds.

# And use date to convert the seconds back to something more meaningful
echo Took `date +%H:%M:%S -ud @${DIFFSEC}`

teckk

05-27-2021 10:11 AM

Code:

#!usr/bin/env/bash



clear



echo -e "Video segment calculator. Calculates run times of segments. 

Enter time with format 01:23:34\n"



read -p "Enter Start time: " start_time

read -p "Enter Stop time:  " stop_time



StartDate=$(date -d "$start_time" +"%s")

EndDate=$(date -d "$stop_time" +"%s")

Diff=$(date -d "0 $EndDate sec - $StartDate sec" +"%H:%M:%S")



echo "                ----------"

echo "Difference is:    "$Diff""

echo "---------------------------"

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