Extract UTC time and find difference

Question

I have a file with the following sample records for buy and sell events

Buy at time=Thu Aug 03 2023 14:13:08 GMT+0200 (Central European Summer Time)

Sell-at time=Thu Aug 03 2023 14:53:02 GMT+0200 (Central European Summer Time)

I want to get whole UTC string from all the lines and get time difference between these records, however, i am not able to extract whole date time string to get differnce between them. i have tried this but not able to get time. Can any one help me out.

while read line
do
    name=$line

    echo $name | sed -e 's/time=\(.*\)(Central/\1/'

done < $1

Solution using shell, awk or sed is required. i can also use GNU date if required

Answer 1

The dconv of dateutils (called dateutils.dconv on Debian-derived systems) has a sed mode to convert dates. So you could convert your timestamps to epoch time with it and awk to print differences between Sell and Buy dates in seconds:

dateutils.dconv -SE -i ' time=%a %b %d %Y %T GMT%Z' -f '=%s=' < your-file |
  awk -F= '$1 == "Buy at"  {buy = $2; next}
           $1 == "Sell-at" {print $2 - buy}'

Answer 2

Assuming you have Bash and GNU/date.

This cuts off the unwanted parts of the date, and then converts a date to epoch (seconds since 01-Jan-1970).

$ Sell='Sell-at time=Thu Aug 03 2023 14:53:02 GMT+0200 (Central European Summer Time)'
$ declare -p Sell
declare -- Sell="Sell-at time=Thu Aug 03 2023 14:53:02 GMT+0200 (Central European Summer Time)"
$ Sell="${Sell/ (*/}"
$ declare -p Sell
declare -- Sell="Sell-at time=Thu Aug 03 2023 14:53:02 GMT+0200"
$ Sell="${Sell/*=}"
$ declare -p Sell
declare -- Sell="Thu Aug 03 2023 14:53:02 GMT+0200"
$ Sell=$( date -d "${Sell}" '+%s' )
$ declare -p Sell
declare -- Sell="1691067182"
$ date -d "@${Sell}"  #.. Check correctness (in UK time).
Thu  3 Aug 13:53:02 BST 2023

Do the same for Buy (maybe declare a function to use twice), and subtract to get the difference in seconds.

Answer 3

Based on How can I output different data from each line?

You need bash and GNU date command.

With ./data-diff-records.sh script:

#! /usr/bin/env bash

declare -r input_filename="$1"

function get_date () {
    local -r -n l_str="$1"
    local -n li_date="$2"
    local l_date="${l_str#*time=}"
    l_date="${l_date% (Central *}"
    # date transformation to seconds since 1st January 1970
    li_date=$(date -d "$l_date" +'%s')
    # printf "date=<%s>=>%d\n" "$l_date" "$li_date"
}

function diff_date () {
    local -r -n l_start_date="$1"
    local -r -n l_end_date="$2"
    local -n l_seconds_diff="$3"
    local -n l_minutes_diff="$4"
    local -n l_hours_diff="$5"
    l_seconds_diff=$(( l_end_date - l_start_date ))
    l_minutes_diff=$(( l_seconds_diff / 60 ))
    l_seconds_diff=$(( l_seconds_diff - ( l_minutes_diff * 60 ) ))
    l_hours_diff=$(( l_minutes_diff / 60 ))
    l_minutes_diff=$(( l_minutes_diff - ( l_hours_diff * 60 ) ))
}

declare -i date_buy=0
declare -i date_sell=0
declare -i seconds_diff=0
declare -i minutes_diff=0
declare -i hours_diff=0
while read -r line; do
    first_token="${line%% *}"
    case "$first_token" in
        "Buy")
            get_date line date_buy
            # echo "first_token=<$first_token> date=<$date_buy>"
        ;;
        "Sell-at")
            get_date line date_sell
            # echo "first_token=<$first_token> date=<$date_sell>"
            diff_date date_buy date_sell seconds_diff minutes_diff hours_diff
            printf "%02d:%02d:%02d\n" "$hours_diff" "$minutes_diff" "$seconds_diff"
        ;;
    esac
done < "$input_filename"

and:

chmod +x ./data-diff-records.sh

Use it like this (where records.log is the input file):

./data-diff-records.sh records.log