Parental Control application for Linux is bit hard to find, if you encounter any then it may be outdated or just don't work as per your wish, they just restrict internet access or sort of stuff. If someone uses your computer or you let your kids use your computer. You can restrict access for them as you want, from now you don't have to say your kids to leave computer, Timekpr will do it better. You can call Timekpr restriction application or parental control application, whatever you like to call it.
Timekpr take control over user account on computer, it will automatically block access for their account, behaves as you configure the restrictions. But it only works with "Standard" accounts, which means those accounts aren't considered administrators/root accounts, but still "Standard" has access to root directory (if added to some groups or sudo is installed). You can limit their daily usage based on a timed access duration and configure periods of day when they can or cannot log in. With this application, administrators can limit account login time duration or account access hours.
In the first tab "status" shows an overview of the selected account, what restrictions placed on the selected user, you can configure access duration or time frame, and whether the account needs to be completely locked. You'll also see several buttons to make quick changes to the selected account. The "Clear all restrictions" button will simply reset all restrictions and is the quickest way to essentially turn off the parental controls for that account. The "Reset time" button allows you to return the "Time left" value back to what it originally was for the day, which you can use in case something went wrong or you had to use the account to set something up. The "Add Time Reward/Penalty" can be used to reward or punish your child by adding to or removing from the amount of time that he or she gets that day. The "Bypass for today" button allows you to turn off the time frame limitations for the day, and the "Lock" button allows you to lock the account so that they cannot log in at all even if there is time remaining and it’s within the time frame.
In the "Limits & Boundaries" tab you can set the access duration and time frame restrictions, simply you have to choose your desired values. It also allows you to configure on a per-day basis rather than have the same values for all days, which you'll need to use if you want to give your child more time or a larger time frame on the weekends.
There is an official PPA but has not updated from years, here is another unofficial PPA for your ease.
Available for Ubuntu 16.04 Xenial/15.10 Wily/15.04 Vivid/14.04 Trusty/12.04 Precise/Linux Mint 18/17/13/other Ubuntu derivatives
To install TimeKpr Parental Control in Ubuntu/Linux Mint open Terminal (Press Ctrl+Alt+T) and copy the following commands in the Terminal:
Which application do you use to restrict computer access for others?