Get the time spent by a process on Linux

I want to measure the time it takes to backup a PostgresSql database, I know I can do time pg_dump ...., but what if I already launched the pg_dump command?.

The process already took more than half an hour, and I don't want to break it right know. I'm pretty sure it will take one more hour (and I'll be at home at that time). I would like to know tomorrow how much time it took.

Solution 1:

You are writing this to file, do you? File modification time would be your answer.

Solution 2:

Just show start time

ps -ax  -o cmd,lstart | grep pg_dump

Or timestamp

ls --time-style=+%s -ld /proc/PROCESS_PID

Or secs elapsed

ls --time-style=+%s -ld /proc/PROCESS_PID | cut -d " " -f6 | \
xargs echo "`date +%s` - $1" | bc