Unix Simulator ( Cygwin )

Happy to share one more software called Cygwin with you.

What it is?
I can say it is a UNIX simulator for MS Windows Machine. I come across this with the help of my good friend Chintav just before a week. As its website describes “Cygwin is a Linux-like environment for Windows ". So, you can do little practice on basic commands of Unix/Linux with this Utility and No need to create separate partition for Linux and make your system dual-boot for windows and Linux. You can download it from provided link. And best thing is that it’s absolutely free, no trial and no limitations. So click on it and start practicing UNIX on your favorite windows machine. Software will tell you more about it and I can say it is very helpful tool. Do try it without hesitation. Have a nice day.

Crontab Functionality

Hi,
Here i m with littel Unix Stuff.

Let's Talk About Unix CRON Jobs.

Crontab ( Cron Table ) Used to Schedule Commands to run at later time.

U Can Find info by Giving man crontab, Here I m giving some info about it.

You can execute crontab if your name appears in the file /usr/lib/cron/cron.allow.
If that file does not exist,
you can usecrontab if your name does not appear in the file /usr/lib/cron/cron.deny.
If only cron.deny exists and is empty, all users can use crontab.
If neither file exists, only the root user can use crontab.

Options for Crontab
----------------------------------------------------------------------------
crontab -e To Edit crontab file.
crontab -l To Display crontab file.
crontab -r Remove crontab file.
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A crontab file has five fields for specifying day , date and time followed by the command to be run at that interval.

Syntex For Crontab is

* * * * * command to be executed

U Can replace 1st * with: hour (0 - 23)
U Can replace 2nd * with: min (0 - 59)
U Can replace 3rd * with: day of month (1 - 31)
U Can replace 4th * with:month (1 - 12)
U Can replace 5th * with:day of week (0 - 6) (Sunday=0)

Example for the Crontab :

30 23 * * * rm /home/user/tmp/*

->it Indicates that, At 23:30 Daily all files from folder /home/user/tmp/ will be removed.


30 23 * 10,12 1-5 rm /home/user/tmp/*

->it Indicates that, At 23:30 every weekdays (Mon-Fri) in Oct & Dec all files from folder /home/user/tmp/ will be removed.

Note: U Can put # as a 1st Character of line & that line will not considered as Cron Job.