CentOS crontab – Automate System Tasks

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July 21, 2018 in News, Tips and Tricks, Ubuntu

CentOS crontab – Automate System Tasks

CentOS crontab – Automate System Tasks

We’ll show you, how to use CentOS crontab. How to automate system tasks on CentOS 7, using Centos crontab. Crontab software utility, is a time-based job scheduler in Unix-like operating systems. Cron is driven by a crontab (cron table) file, a configuration file that specifies shell commands to run periodically on a given schedule. The crontab files are stored where the lists of jobs and other instructions to the cron daemon are kept. Users can have their own individual crontab files and often there is a system-wide crontab file (usually in /etc or a subdirectory of /etc) that only system administrators can edit.


1. Connect via SSH and update the system software

First of all, connect to your Linux VPS via SSH and update all your system software to the latest version available. You can use the following command to do that:

sudo yum update

2.  Verify if cronie package is installed

To automate the system tasks, or better known as jobs under Linux, you can use an utility called Cron. Using Cron you can run scripts automatically within a specified period of time, create backup of your databases or other important files, monitor the services running on your server and many other things. To use the Cron utility, you need to install the cronie package on your system. It should be already installed on your server. To confirm, issue the following command:

sudo rpm -q cronie

3. Install cronie package

If it is not installed, you can use yum to install it. Yum is a package manager which you can use to install and manage software on CentOS 7. Run the command below:

sudo yum install cronie

4. Check if  crond service is running

The cron jobs are picked by the crond service. To check whether the crond service is running on your CentOS VPS, you can use the following command:

sudo systemctl status crond.service

5. Configure cron jobs

To configure cron jobs you need to modify the /etc/crontab file. Please note that it can only be modified by the root user. To check the current configuration, you can use the following command:

sudo cat /etc/crontab

The output should be similar to the one below:

SHELL=/bin/bash
PATH=/sbin:/bin:/usr/sbin:/usr/bin
MAILTO=root

# For details see man 4 crontabs

# Example of job definition:
# .---------------- minute (0 - 59)
# |  .------------- hour (0 - 23)
# |  |  .---------- day of month (1 - 31)
# |  |  |  .------- month (1 - 12) OR jan,feb,mar,apr ...
# |  |  |  |  .---- day of week (0 - 6) (Sunday=0 or 7) OR sun,mon,tue,wed,thu,fri,sat
# |  |  |  |  |
# *  *  *  *  * user-name  command to be executed
37 * * * * root run-parts /etc/cron.hourly
23 5 * * * root run-parts /etc/cron.daily
19 3 * * 0 root run-parts /etc/cron.weekly
23 0 6 * * root run-parts /etc/cron.monthly

As you can see the crontab file already contain explanation about how to define your own jobs. The syntax is the following:

minute hour day month day_of_week username command

An asterisk (*) in the crontab can be used to specify all valid values, so if you like command to be executed every day at midnight, you can add the following cron job:

0 0 * * * root /sample_command >/dev/null 2>&1

Your cron job will be run at:

2016-06-10 00:00:00
2016-06-11 00:00:00
2016-06-12 00:00:00
2016-06-13 00:00:00
2016-06-14 00:00:00
...

Specific users can create cron jobs too. The cron jobs for specific users are located in /var/spool/cron/username. When you create cron jobs for specific users you do not need to specify the username in the cron job. Therefore the syntax will be like the one below:

minute hour day month day_of_week command

6.  Restart the crond service

After you make the changes restart the crond service using the command below:

sudo systemctl restart crond.service

For more information you can check the man pages:

man cron

and

man crontab

If it is difficult for you to set up correct cron jobs at the beginning, you can use some cron job calculator to generate the cron job expression. There are several good cron job calculators available on the Internet.

Read Also: Ubuntu crontab

Of course you don’t have to use CentOs crontab, if you use one of our CentOS VPS hosting services, in which case you can simply ask our expert Linux admins to help you with crontab on CentOS to Automate system tasks. They are available 24×7 and will take care of your request immediately.

PS. If you liked this post, on how to use the CentOS crontab,  please share it with your friends on the social networks using the buttons on the left or simply leave a reply below. Thanks.

July 12, 2018 in Laravel, News, Tips and Tricks, Ubuntu

how to install laravel

how to install laravel

Install Composer

Laravel utilizes Composer to manage its dependencies. First, download a copy of the composer.phar. Once you have the PHAR archive, you can either keep it in your local project directory or move to usr/local/bin to use it globally on your system. On Windows, you can use the Composer Windows installer.

Install Laravel

Via Laravel Installer

First, download the Laravel installer using Composer.

composer global require "laravel/installer=~1.1"

Make sure to place the ~/.composer/vendor/bin directory in your PATH so the laravelexecutable is found when you run the laravel command in your terminal.

Once installed, the simple laravel new command will create a fresh Laravel installation in the directory you specify. For instance, laravel new blog would create a directory named blog containing a fresh Laravel installation with all dependencies installed. This method of installation is much faster than installing via Composer.

Via Composer Create-Project

You may also install Laravel by issuing the Composer create-project command in your terminal:

composer create-project laravel/laravel {directory} 4.2 --prefer-dist

Via Download

Once Composer is installed, download the 4.2 version of the Laravel framework and extract its contents into a directory on your server. Next, in the root of your Laravel application, run the php composer.phar install (or composer install) command to install all of the framework’s dependencies. This process requires Git to be installed on the server to successfully complete the installation.

If you want to update the Laravel framework, you may issue the php composer.phar updatecommand.

Server Requirements

The Laravel framework has a few system requirements:

  • PHP >= 5.4
  • MCrypt PHP Extension

As of PHP 5.5, some OS distributions may require you to manually install the PHP JSON extension. When using Ubuntu, this can be done via apt-get install php5-json.

Configuration

The first thing you should do after installing Laravel is set your application key to a random string. If you installed Laravel via Composer, this key has probably already been set for you by the key:generate command. Typically, this string should be 32 characters long. The key can be set in the app.php configuration file. If the application key is not set, your user sessions and other encrypted data will not be secure.

Laravel needs almost no other configuration out of the box. You are free to get started developing! However, you may wish to review the app/config/app.php file and its documentation. It contains several options such as timezone and locale that you may wish to change according to your application.

Once Laravel is installed, you should also configure your local environment. This will allow you to receive detailed error messages when developing on your local machine. By default, detailed error reporting is disabled in your production configuration file.

Note: You should never have app.debug set to true for a production application. Never, ever do it.

Permissions

Laravel may require one set of permissions to be configured: folders within app/storagerequire write access by the web server.

Paths

Several of the framework directory paths are configurable. To change the location of these directories, check out the bootstrap/paths.php file.

Pretty URLs

Apache

The framework ships with a public/.htaccess file that is used to allow URLs without index.php. If you use Apache to serve your Laravel application, be sure to enable the mod_rewrite module.

If the .htaccess file that ships with Laravel does not work with your Apache installation, try this one:

Options +FollowSymLinks
RewriteEngine On

RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^ index.php [L]

Nginx

On Nginx, the following directive in your site configuration will allow “pretty” URLs:

location / {
    try_files $uri $uri/ /index.php?$query_string;
}

June 5, 2018 in Tips and Tricks, Ubuntu

How to zip the directory in linux with command line

In this tutorial we will learn,how to zip the directory in linux with command line.Zip is a compression and file packaging utility for Linux,Unix,Windows and various Operating system. The zip helps to compress and reduce the size of file and directory.To zip a directory,first of all we will check ,do we have zip command installed in Linux system.

Note: For more detailed zip examples with command line, read out this post (How to zip directory in linux explained with examples).

The below command will help to find is zip installed or not.

# which zip   (It will show the absolute path of zip)

In CentOS

# rpm -q zip

In Debian or Ubuntu

$ sudo dpkg -l zip

If you find it is not installed in system then install with given below command.

In CentOS or Red hat
# yum install zip

In Debian or Ubuntu
$ sudo apt-get install zip

After confirmation of installed zip package,now we will zip or compress the directory in Linux system.
Use the given below command.

zip -r GiveAnyName.zip  /path/of/Directory

for eg.
 We have a backup directory in /root/ (i.e /root/backup)

zip -r backup.zip /root/backup

The command will compress the directory with extension .zip .
In above given eg. the compressed file name would be backup.zip

zip linux command exclude folder

zip -r myarchive.zip dir1 -x dir1/ignoreDir1/**\* dir1/ignoreDir2/**\*