Cron is an amazing job scheduler. But, when it comes to running your scripts in less than every minute, it can’t help.
With Cron, you can run your scripts every minute, but not in shorter period of time.
This problem can be solved with simple bash script. For example, if you need to run a PHP script on every 20 seconds, you can create a bash script like this:
#!/bin/bash #Name:myscript.sh #Desc:Run script in every 20 seconds while (sleep 20 && php /path_to_your_script/your_script_name.php) & do wait $! done
Then, make script executable, and add it to the system startup. That’s all.
Somehow, you crashed your Linux. It’s completely frozen. You try pressing Ctrl + Alt + Backspace, but doesn’t help.
What to do? Someone would press the power button and restart or shut down the system. You shouldn’t do this. This can make you a lot of problems.
What you can do, is to perform a gentle Linux restart. This is much safer way to restart your frozen Linux. To do this, you need to press:
Ctrl + Alt + PrtSc (SysRq) + reisub
Just to make it clear. You need to press and hold Ctrl, Alt and PrtSc(SysRq) buttons, and while holding them, you need to press r, e, i, s, u, b
This will restart your Linux safely.
It’s possible that you’ll have problem to reach all the buttons you need to press. I’ve seen people type reisub with their nose
So, here’s my suggestion: With your smallest finger on the left hand, press Ctrl. With your thumb on left hand, press Alt. With the smallest finger on your right hand press PrtSc(SysRq) button. This way, you’ll be able to access to reisub buttons with your other fingers.
Okay, but what this REISUB means?
- R: Switch the keyboard from raw mode to XLATE mode
- E: Send the SIGTERM signal to all processes except init
- I: Send the SIGKILL signal to all processes except init
- S: Sync all mounted filesystems
- U: Remount all mounted filesystems in read-only mode
- B: Immediately reboot the system, without unmounting partitions or syncing
You can find the complete list here. There you can see that o shuts down the system. So, if you want to turn off your PC when your Linux crash, you can use this combination:
Ctrl + Alt + PrtSc (SysRq) + reisuo
So, imagine that you are in front of some Linux computer to which you don’t have any access. How do you get a root access?
Restart the computer, in Grub menu choose (recovery mode) and on the next screen select Drop to root shell prompt. Simple as that.
New research from Adam Grant, the youngest tenured professor at the University of Pennsylvania’s Wharton School of Management, is really intriguing. In his study, Grant collected data from sales representatives at a software company. He began by giving reps an often-used personality assessment that measures introversion and extroversion on a 1-to-7 scale, with 1 being most introverted and 7 being most extroverted.
Then he tracked their performance over the next three months.
The introverts fared worst; they earned average revenue of $120 per hour.
The extroverts performed slightly better, pulling in $125 per hour. But neither did nearly as well as a third group: the ambiverts.
In Grant’s study, ambiverts earned average hourly revenues of $155, beating extroverts by a healthy 24 percent.
Who are Ambiverts?
Ambiverts, a term coined by social scientists in the 1920s, are people who are neither extremely introverted nor extremely extroverted. Think back to that 1-to-7 scale that Grant used. Ambiverts aren’t 1s or 2s, but they’re not 6s or 7s either. They’re 3s, 4s and 5s. They’re not quiet, but they’re not loud. They know how to assert themselves, but they’re not pushy.