How to Measure the Length of Execution of a Selected Portion of Code in Bash

The aim of this page📝 is to share a simple way of measuring the duration of a selected portion of code execution in bash.

1. I am using ms unit
2. To get the absolute timestamp, use $(date +%s%N | cut -b1-13)

• %s for seconds since the UNIX epoch
• %N adding nanosecond portion
• cut is selecting the first 13 fields of the nanosecond portion => milliseconds

/$ date +%s
1673595770
/$ date +%s%N
1673595775334609500
/$ $(date +%s%N | cut -b1-13)
1673595775334

1. Get the absolute timestamp at the beginning of the program
2. Get the absolute timestamp at the end of the program
3. Subtract end - beginning to get the duration
4. print it

start_prog=$(date +%s%N | cut -b1-13)

#PROGRAM

end_prog=$(date +%s%N | cut -b1-13)

prog_time_ms=$(("$end_prog" - "$start_prog"))
echo "INFO: prog finished in '${prog_time_ms} ms'"

…you could also do date +%s%3N

/$ date +%s%3N
1673596128544

LINKS

• https://serverfault.com/questions/151109/how-do-i-get-the-current-unix-time-in-milliseconds-in-bash