Engineering and technology notes

Crontab Day of the Week syntax

0 and 7 both stand for Sunday, you can use the one you want, so writing 0-6 or 1-7 has the same result.

Also, as suggested by @Henrik, it is possible to replace numbers by shortened name of days, such as MON, THU, etc:

0 - Sun      Sunday
1 - Mon      Monday
2 - Tue      Tuesday
3 - Wed      Wednesday
4 - Thu      Thursday
5 - Fri      Friday
6 - Sat      Saturday
7 - Sun      Sunday

Graphically:

 ┌────────── minute (0 - 59)
 │ ┌──────── hour (0 - 23)
 │ │ ┌────── day of month (1 - 31)
 │ │ │ ┌──── month (1 - 12)
 │ │ │ │ ┌── day of week (0 - 6 => Sunday - Saturday, or
 │ │ │ │ │                1 - 7 => Monday - Sunday)
 ↓ ↓ ↓ ↓ ↓
 * * * * * command to be executed

Finally, if you want to specify day by day, you can separate days with commas, for example SUN,MON,THU will exectute the command only on sundays, mondays on thursdays.

https://stackoverflow.com/questions/18919151/crontab-day-of-the-week-syntax

Crontab Day of the Week syntax was last modified: May 23rd, 2020 by Jovan Stosic

How to see time stamps in bash history?

HISTTIMEFORMAT="%d/%m/%y %T "  # for e.g. “29/02/99 23:59:59”
HISTTIMEFORMAT="%F %T "        # for e.g. “1999-02-29 23:59:59”

To make the change permanent for the current user run:

echo 'HISTTIMEFORMAT="%d/%m/%y %T "' >> ~/.bashrc  # or respectively
echo 'HISTTIMEFORMAT="%F %T "' >> ~/.bashrc
source ~/.bashrc

To test the effects run:

history

https://askubuntu.com/questions/391082/how-to-see-time-stamps-in-bash-history

How to see time stamps in bash history? was last modified: May 23rd, 2020 by Jovan Stosic