Date: 2017may10 OS: Linux Language: bash Q. bash: How can I get the milliseconds since the start of the epoch A. Use the + option of the date command.

%s is the seconds %N is the nanoseconds %3N is the first 3 digits of the nanoseconds (doesn't work on all systems)

So:

date '+%s%3N' If %3N works for you

Otherwise:

$(( $(date +%s%N) / 1000000 ))

By the way, to get the seconds since the start of the epoch (January 1, 1970):

date '+%s'