mac os terminal shell script for time tracking - bash

Question

There are two functions : start и stop
they write the date and time to the file wrk.txt
This is what the contents of the file looks like after executing these commands:
START 10-08-2022 08:00:00
STOP 10-08-2022 08:06:33
function code:
#!/bin/bash
function start { echo 'START' $(date '+%d-%m-%Y %H:%M:%S') >> ~/Documents/wrk.txt
echo 'work started at:' $(date '+%d-%m-%Y %H:%M:%S') }
function stop { echo 'STOP' $(date '+%d-%m-%Y %H:%M:%S') >> ~/Documents/wrk.txt
echo 'work finished at:' $(date '+%d-%m-%Y %H:%M:%S')
}`
Question: how to take the last two lines from the file, remove the word START or STOP and calculate the time difference and save the result to a file
file data before calculations:
START 10-08-2022 08:00:00
STOP 10-08-2022 08:06:33
expected file data after calculations:
START 10-08-2022 08:00:00
STOP 10-08-2022 08:06:33
totalworktime: 00:06:33

Answer 1

The following may work for you:
#!/bin/bash
output_file="${1:-time_delta.out}"
df="%m-%d-%Y %H:%M:%S"
start=$(awk '{this=last; last=$0} END{print this}' wrk.txt)
sdate="${start/START /}"
end=$(awk '{this=last; last=$0} END{print last}' wrk.txt)
edate="${end/END /}"
printf "%s\n%s\n" "$start" "$end" >> "${output_file}"
echo $(( $(date -j -f "$df" "${edate}" +%s) \
- $(date -j -f "$df" "${sdate}" +%s) )) \
| awk '{printf("totalworktime: %02d:%02d:%02d\n", ($1/60/60),($1/60%60),($1%60))}' >> "${output_file}"
1) Set variable containing desired output file path/name either from first parameter passed to script or will default to ./time_delta.out. Set the date format expected from the wrk.txt contents.
output_file="${1:-time_delta.out}"
df="%m-%d-%Y %H:%M:%S"
2) Parse the second to the last line and the last line from wrk.txt and store the raw lines in variables start and end. Remove the leading START and END text from each variable using bash string replacement and store the results in sdate and edate variables.
start=$(awk '{this=last; last=$0} END{print this}' wrk.txt)
sdate="${start/START /}"
end=$(awk '{this=last; last=$0} END{print last}' wrk.txt)
edate="${end/END /}"
3) Add the raw $start AND $end variable contents to the $output_file
printf "%s\n%s\n" "$start" "$end" >> "${output_file}"
4) Convert the $sdate and $edate values to seconds from the epoch via date -j -f "$df" "${sdate}" +%s and date -j -f "$df" "${edate}" +%s. Subtract those values to get the delta and pass the result to awk for formatting as HH:MM:SS and append to ${output_file}
echo $(( $(date -j -f "$df" "${edate}" +%s) \
- $(date -j -f "$df" "${sdate}" +%s) )) \
| awk '{printf("totalworktime: %02d:%02d:%02d\n", ($1/60/60),($1/60%60),($1%60))}' >> "${output_file}"
Note, you might also consider replacing your start and stop functions with a single parameterized
function. At a minimum, store the date in a variable to avoid duplicate calls to date. Something
like the following:
add_time_log() {
local label="${1:-START}"
local msg="${2:-work started at}"
local log_file="${3:-time_log.txt}"
local now=$(date +"%m-%d-%Y %H:%M:%S")
printf "${msg}: ${now}\n"
printf "${label} ${now}\n" >> "${log_file}"
}
You can call the function as follows:
The folowing 2 are equivalent due to default parameter values
add_time_log
add_time_log START "work started at"
Adding END log
add_time_log END "work finished at"
Specifying all 3 parameters
add_time_log START "work started at" out.txt
add_time_log END "work finished at" out.txt