<p>In this tutorial, we will show you how to use the&nbsp;<code>shutdown</code>&nbsp;command through practical examples and detailed explanations of the most common&nbsp;<code>shutdown</code>&nbsp;options.</p>



<p>The&nbsp;<code>shutdown</code>&nbsp;command brings the system down in a secure way. When the&nbsp;<code>shutdown</code>&nbsp;is initiated, all logged-in users and processes are notified that the system is going down, and no further logins are allowed. You can shut down your system immediately or at the specified time.</p>



<h2 id="shutdown-command-syntax">Shutdown Command Syntax</h2>



<p>Before going into how to use the&nbsp;<code>shutdown</code>&nbsp;command, let’s start by reviewing the basic syntax.</p>



<p>The&nbsp;<code>shutdown</code>&nbsp;command expressions take the following form:</p>



<pre class="wp-block-code"><code>shutdown &#91;OPTIONS] &#91;TIME] &#91;MESSAGE]</code></pre>



<ul><li><code>options</code>&nbsp;-&nbsp;<a href="http://man7.org/linux/man-pages/man8/shutdown.8.html" target="_blank" rel="noreferrer noopener nofollow">Shutdown options</a>&nbsp;such as halt, power-off (the default option) or reboot the system.</li><li><code>time</code>&nbsp;- The time argument specifies when to perform the shutdown process.</li><li><code>message</code>&nbsp;- The message argument specifies a message which will be broadcast to all users.</li></ul>



<p>On the recent Linux distributions&nbsp;<code>shutdown</code>&nbsp;is an alias to&nbsp;<code>systemctl</code>&nbsp;and it is available in the system only for compatibility reasons.</p>



<h2 id="how-to-use-the-shutdown-command">How to Use the&nbsp;<code>shutdown</code>&nbsp;Command</h2>



<p>Only the root and users with&nbsp;<code>sudo</code>&nbsp;privileges can use&nbsp;<code>crontab</code>&nbsp;command.</p>



<p>When used with no arguments, the&nbsp;<code>shutdown</code>&nbsp;command will power off the machine.</p>



<pre class="wp-block-code"><code>sudo shutdown</code></pre>



<figure class="wp-block-image size-large"><img src="http://ec2-13-127-91-65.ap-south-1.compute.amazonaws.com/wp-content/uploads/2020/12/shutdown.jpg" alt="" class="wp-image-763"/></figure>



<p>The shutdown process starts after 1 minute, which is the default time interval.</p>



<h2 id="how-to-shutdown-the-system-at-a-specified-time">How to Shutdown the System at a Specified Time</h2>



<p>The time argument can have two different formats. It can be an absolute time in the format&nbsp;<code>hh:mm</code>&nbsp;and relative time in the format&nbsp;<code>+m</code>&nbsp;where m is the number of minutes from now.</p>



<p>The following example will schedule system shutdown at 11 A.M:</p>



<pre class="wp-block-code"><code>sudo shutdown 11:00</code></pre>



<p>The following example will schedule system&nbsp;<code>shutdown</code>&nbsp;in 10 minutes from now:</p>



<pre class="wp-block-code"><code>sudo shutdown +10</code></pre>



<h2 id="how-to-shutdown-the-system-immediately">How to Shutdown the System Immediately</h2>



<p>To shut down your system immediately you can use&nbsp;<code>+0</code>&nbsp;or its alias&nbsp;<code>now</code>:</p>



<pre class="wp-block-code"><code>sudo shutdown now</code></pre>



<h2 id="how-to-broadcast-a-custom-message">How to Broadcast a Custom Message</h2>



<p>To broadcast a custom message along with the standard&nbsp;<code>shutdown</code>&nbsp;notification type your message after the time argument.</p>



<p>The following example, will shut down the system in 30 minutes from now and notify the users that a hardware upgrade will be performed:</p>



<pre class="wp-block-code"><code>sudo shutdown +30 "Hardware upgrade"</code></pre>



<p>It is important to mention that when specifying a custom wall message, you must specify a time argument too.</p>



<h2 id="how-to-reboot-the-system">How to Reboot the System</h2>



<p>To reboot the system, use the&nbsp;<code>-r</code>&nbsp;argument:</p>



<pre class="wp-block-code"><code>sudo shutdown -r</code></pre>



<p>You can also specify a time argument and a custom message:</p>



<pre class="wp-block-code"><code>shutdown -r +5 "Updating kernel"</code></pre>



<p>The command above will reboot the system after 5 minutes and broadcast&nbsp;<code>Updating kernel</code>.</p>



<h2 id="how-to-cancel-a-scheduled-shutdown">How to Cancel a Scheduled Shutdown</h2>



<p>If you have scheduled shutdown and you want to cancel it, you can use the&nbsp;<code>-c</code>&nbsp;argument:</p>



<pre class="wp-block-code"><code>sudo shutdown -c</code></pre>



<p>When canceling a scheduled shutdown, you cannot specify a time argument, but you can still broadcast a message that will be sent to all users.</p>



<pre class="wp-block-code"><code>sudo shutdown -c "Canceling the reboot"</code></pre>



<h2 id="conclusion">Conclusion</h2>



<p>The&nbsp;<code>shutdown</code>&nbsp;command allows you to halt, power-off and reboot your Linux system.</p>



<p>To learn more about&nbsp;<code>shutdown</code>, visit the&nbsp;<a href="https://linux.die.net/man/8/shutdown" rel="noreferrer noopener" target="_blank">shutdown man</a>&nbsp;page.</p>



<p>If you have any questions or feedback, feel free to leave a comment.</p>

In this tutorial, we will show you how to use the&nbsp;shutdown&nbsp;command through practical examples and detailed explanations of the most com...

Linux Shutdown Command - TCMHACK

Linux Shutdown Command

<p>Let’s Encrypt is a free SSL provider. Porkbun is very good domain registrar. We can download free SSL from porkbun dashboard. All we need is to upload it into our VPS server and need to add the path of the certificates into virtual host file.</p>



<p>Download SSL from porkbun.</p>



<div class="wp-block-image"><figure class="aligncenter size-large"><img src="http://ec2-13-127-91-65.ap-south-1.compute.amazonaws.com/wp-content/uploads/2020/07/porkbun-1024x617.jpg" alt="" class="wp-image-702"/></figure></div>



<p>You shall get a ZIP file containing the following 4 files:-</p>



<ol><li>domain.cert.pem</li><li>intermediate.cert.pem</li><li>private.key.pem</li><li>public.key.pem</li></ol>



<p>Now Upload file no. 1 and 3 only (i.e. domain.cert.pem and private.key.pem) into your VPS home folder (i.e. /home/admin/).</p>



<p>Create a Virtual Host for your domain (for example: yourdomain.com) as shown below:</p>



<pre class="wp-block-code"><code>sudo nano /etc/nginx/sites-available/wbxpress.net.conf</code></pre>



<pre class="wp-block-code"><code>server {
    server_name    yourdomain.com www.yourdomain.com;
    root           /var/www/yourdomain;
    index          index.html index.php;

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

    location ~* \.php$ {
        fastcgi_pass unix:/run/php/php7.2-fpm.sock;
        include         fastcgi_params;
        fastcgi_param   SCRIPT_FILENAME    $document_root$fastcgi_script_name;
        fastcgi_param   SCRIPT_NAME        $fastcgi_script_name;
    }

    listen 443 ssl http2;
    listen &#91;::]:443 ssl http2;

    ssl_certificate /home/admin/domain.cert.pem;
    ssl_certificate_key /home/admin/private.key.pem;	
}
server {
    if ($host = www.yourdomain.com) {
        return 301 https://yourdomain.net$request_uri;
    }
    if ($host = yourdomain.com) {
        return 301 https://yourdomain.net$request_uri;
    }
    listen 80;
    listen &#91;::]:80;
    server_name yourdomain.com www.yourdomain.com;
    return 404;
}</code></pre>



<p>Also, we need to replace SSL settings as found from <a href="https://mozilla.github.io/server-side-tls/ssl-config-generator/" target="_blank" rel="noreferrer noopener">SSL Config File Generator</a> at nginx.conf file.</p>



<pre class="wp-block-code"><code>sudo nano /etc/nginx/nginx.conf</code></pre>



<pre class="wp-block-preformatted">ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers 'ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS';
ssl_prefer_server_ciphers on;</pre>



<p>The above configuration works perfectly well in our case.</p>

Let’s Encrypt is a free SSL provider. Porkbun is very good domain registrar. We can download free SSL from porkbun dashboard. All we need is to u...

How to Install a Porkbun SSL on NGINX - TCMHACK

How to Install a Porkbun SSL on NGINX

<p>In this tutorial we are going to show you, with step-by-step instructions on how to install Let’s Encrypt with Apache on Ubuntu.</p>



<p>Let’s Encrypt is an open SSL Certificate Authority (CA) that offers free domain-validated (DV) certificates for your websites. SSL Certificates are used to establish a secure encrypted connection between a web server and a user’s web browser. The SSL certificates that have been issued by Let’s Encrypt are valid for 90 days and are trusted by most web browsers today.</p>



<h2>1. Requirements</h2>



<p>In order to start with the installation procedure, you need to have Apache or Nginx installed on your server. If there is no web server installed on your virtual server, please follow this tutorial to install Apache.</p>



<p>Also, you need a registered domain name with its A record pointing to your server’s IP address. For the purposes of this tutorial, we will use ‘yourdomain.com’.</p>



<h2>2. Install CertBot</h2>



<p>Run the following commands:</p>



<pre class="wp-block-code"><code>sudo apt-get install software-properties-common python-software-properties
sudo add-apt-repository ppa:certbot/certbot
sudo apt-get update
sudo apt-get install python-certbot-apache</code></pre>



<h2>3. Install Let’s Encrypt SSL</h2>



<p>Install Let’s Encrypt SSL certificate on your domain (do not forget to replace ‘yourdomain.com’ with your actual domain):</p>



<pre class="wp-block-code"><code>sudo certbot --apache -d yourdomain.com</code></pre>



<pre class="wp-block-preformatted">Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator apache, Installer apache
Enter email address (used for urgent renewal and security notices) (Enter 'c' to
cancel): admin@yourdomain.com

Please read the Terms of Service at
https://letsencrypt.org/documents/LE-SA-v1.2-November-15-2017.pdf. You must
agree in order to register with the ACME server at
https://acme-v01.api.letsencrypt.org/directory
(A)gree/(C)ancel: A

Would you be willing to share your email address with the Electronic Frontier
Foundation, a founding partner of the Let's Encrypt project and the non-profit
organization that develops Certbot? We'd like to send you email about EFF and
our work to encrypt the web, protect its users and defend digital rights.
(Y)es/(N)o: N
Obtaining a new certificate
Performing the following challenges:
tls-sni-01 challenge for linuxhostsupport.com
Waiting for verification…
Cleaning up challenges
Created an SSL vhost at /etc/apache2/sites-available/000-default-le-ssl.conf
Deploying Certificate for yourdomain.com to VirtualHost /etc/apache2/sites-available/000-default-le-ssl.conf
Enabling available site: /etc/apache2/sites-available/000-default-le-ssl.conf</pre>



<h2>4. Redirect HTTP traffic to HTTPS</h2>



<pre class="wp-block-preformatted">Please choose whether or not to redirect HTTP traffic to HTTPS, removing HTTP access.
1: No redirect - Make no further changes to the webserver configuration.
2: Redirect - Make all requests redirect to secure HTTPS access. Choose this for
new sites, or if you're confident your site works on HTTPS. You can undo this
change by editing your web server's configuration.
Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 2
Redirecting vhost in /etc/apache2/sites-enabled/000-default.conf to ssl vhost in /etc/apache2/sites-available/000-default-le-ssl.conf

Congratulations! You have successfully enabled https://yourdomain.com</pre>



<h2>5. Renew the SSL certificate with a cron job</h2>



<p>Create a cron job so the SSL certificate is renewed automatically. Run:</p>



<pre class="wp-block-code"><code>crontab -e</code></pre>



<p>and add the following line:</p>



<pre class="wp-block-code"><code>0 0 1 * * /usr/bin/letsencrypt renew >> /var/log/letsencrypt-renew.log</code></pre>



<p>Save and close that file and restart cron service for the changes to take effect:</p>



<pre class="wp-block-code"><code>service cron restart</code></pre>



<p>Open https://yourdomain.com in your favorite web browser, and check whether Let’s Encrypt SSL is installed properly:</p>



<figure class="wp-block-image size-large"><img src="http://ec2-13-127-91-65.ap-south-1.compute.amazonaws.com/wp-content/uploads/2020/07/ssl-secure-screenshot.png" alt="" class="wp-image-698"/></figure>



<p>That is it. Let’s Encrypt SSL certificate has been successfully installed on your website.</p>

In this tutorial we are going to show you, with step-by-step instructions on how to install Let’s Encrypt with Apache on Ubuntu.



Let’s Encrypt...

How to install Let's Encrypt on Apache2 - TCMHACK

How to install Let's Encrypt on Apache2

New Linux converts coming from the Windows world may find working with the command line to be somewhat intimidating. However, it's not that diffi...

Basic & Useful Linux Commands - TCMHACK

Basic & Useful Linux Commands

<p><strong>Cron</strong> allows Linux and Unix users to run commands or scripts at a given date and time. You can schedule scripts to be executed periodically. Cron is one of the most useful tool in a Linux or UNIX like operating systems. It is usually used for sysadmin jobs such as backups or cleaning <em>/tmp/ </em>directories and more. The cron service (daemon) runs in the background and constantly checks the <em>/etc/crontab</em> file, and <em>/etc/cron.*/</em> directories. It also checks the<em> /var/spool/cron/</em> directory.</p>



<h2>Types of cron configuration files</h2>



<p>There are different types of configuration files:</p>



<ul><li><strong>The UNIX / Linux system <a href="http://ec2-13-127-91-65.ap-south-1.compute.amazonaws.com/what-is-crontab/">crontab</a>:</strong> Usually, used by system services and critical jobs that requires root like privileges. The sixth field (see below for field description) is the name of a user for the command to run as. This gives the system crontab the ability to run commands as any user.</li><li><strong>The user crontabs:</strong> User can install their own cron jobs using the crontab command. The sixth field is the command to run, and all commands run as the user who created the crontab</li></ul>



<h2>How Do I install or create or edit my own cron jobs?</h2>



<p>To edit or create your own crontab file, type the following command at the UNIX / Linux shell prompt:</p>



<pre class="wp-block-code"><code>crontab -e</code></pre>



<h2>Do I have to restart cron after changing the crontable file?</h2>



<p>No. Cron will examine the modification time on all crontabs and reload those which have changed. Thus cron need not be restarted whenever a crontab file is modified.</p>



<h2><strong>Syntax of crontab</strong></h2>



<p>The syntax is:</p>



<pre class="wp-block-code"><code>* * * * * /path/to/command args1 args2</code></pre>



<p>Where</p>



<ul><li><strong>First Star:</strong> Minute (0-59)</li><li><strong>Second Star:</strong> Hours (0-23)</li><li><strong>Third Star:</strong> Day (0-31)</li><li><strong>Fourth Star:</strong> Month (0-12 [12 == December])</li><li> <strong>Fifth Star:</strong> Day of the week(0-7 [7 or 0 == sunday])</li><li><strong>/path/to/command</strong> – Script or command name to schedule</li><li><strong>args1: </strong>any other required arguments (Optional)</li></ul>



<p>Easy to remember format:</p>



<pre class="wp-block-code"><code>* * * * * command to be executed
- - - - -
| | | | |
| | | | ----- Day of week (0 - 7) (Sunday=0 or 7)
| | | ------- Month (1 - 12)
| | --------- Day of month (1 - 31)
| ----------- Hour (0 - 23)
------------- Minute (0 - 59)</code></pre>



<h2>How do I use operators?</h2>



<p>An operator allows you to specifying multiple values in a field. There are three operators:</p>



<ol><li><strong>The asterisk (*)&nbsp;</strong>: This operator specifies all possible values for a field. For example, an asterisk in the hour time field would be equivalent to every hour or an asterisk in the month field would be equivalent to every month.</li><li><strong>The comma (,)</strong>&nbsp;: This operator specifies a list of values, for example: “1,5,10,15,20, 25”.</li><li><strong>The dash (-)</strong>&nbsp;: This operator specifies a range of values, for example: “5-15” days , which is equivalent to typing “5,6,7,8,9,….,13,14,15” using the comma operator.</li><li><strong>The separator (/)</strong>&nbsp;: This operator specifies a step value, for example: “0-23/” can be used in the hours field to specify command execution every other hour. Steps are also permitted after an asterisk, so if you want to say every two hours, just use */2</li></ol>



<h2>Use special string to save time</h2>



<p>Instead of the first five fields, you can use any one of eight special strings. It will not just save your time but it will improve readability.</p>



<figure class="wp-block-table"><table class=""><tbody><tr><td>Special string</td><td>Meaning</td></tr><tr><td>@reboot</td><td>Run once, at startup.</td></tr><tr><td>@yearly</td><td>Run once a year, “0 0 1 1 *”.</td></tr><tr><td>@annually</td><td>(same as @yearly)</td></tr><tr><td>@monthly</td><td>Run once a month, “0 0 1 * *”.</td></tr><tr><td>@weekly</td><td>Run once a week, “0 0 * * 0”.</td></tr><tr><td>@daily</td><td>Run once a day, “0 0 * * *”.</td></tr><tr><td>@midnight</td><td>(same as @daily)</td></tr><tr><td>@hourly</td><td>Run once an hour, “0 * * * *”.</td></tr></tbody></table></figure>



<h2>Examples</h2>



<p>Run ntpdate command every hour:</p>



<pre class="wp-block-code"><code>@hourly /path/to/ntpdate</code></pre>



<p>Make a backup everyday:</p>



<pre class="wp-block-code"><code>@daily /path/to/backup/script.sh</code></pre>



<p></p>

Cron allows Linux and Unix users to run commands or scripts at a given date and time. You can schedule scripts to be executed periodically. Cron ...

What are Cronjobs? - TCMHACK

What are Cronjobs?

<h2>Name</h2>



<p>C<strong>rontab</strong> - files used to schedule the execution of programs</p>



<h2>Description</h2>



<p>A crontab file contains instructions for the <strong>cron</strong> daemon in the following simplified manner: "run this command at this time on this date".  Each user can define their own crontab.  Commands defined in any given crontab are executed under the user who owns that particular crontab.  Uucp and News usually have their own crontabs, eliminating the need for explicitly running su as part of a cron command.</p>



<p>Blank lines, leading spaces, and tabs are ignored.  Lines whose first non-white space character is a pound-sign (#) are comments, and are not processed.  Note that comments are not allowed on the same line as cron commands, since they are considered a part of the command. Similarly, comments are not allowed on the same line as environment variable settings.</p>



<p>An active line in a crontab is either an environment setting or a cron command.  An environment setting is of the form:</p>



<pre class="wp-block-preformatted">name = value</pre>



<p>where the white spaces around the equal-sign (=) are optional, and any subsequent non-leading white spaces in <em><strong>value</strong></em> is a part of the value assigned to <strong><em>name</em></strong>.  The <em><strong>value</strong></em> string may be placed in quotes (single or double, but matching) to preserve leading or trailing white spaces.</p>



<p>Several environment variables are set up automatically by the cron daemon.  <strong><em>SHELL</em></strong> is set to <em>/bin/sh</em>, and <em><strong>LOGNAME</strong></em> and <em><strong>HOME</strong></em> are set from the <em>/etc/passwd</em> line of the crontab´s owner.  <em><strong>HOME</strong></em> and <em><strong>SHELL</strong></em> can be overridden by settings in the crontab; <em><strong>LOGNAME</strong></em> can not.</p>



<p>(Note: the <strong><em>LOGNAME</em></strong> variable is sometimes called <strong><em>USER</em></strong> on <strong><em>BSD</em></strong> systems and is also automatically set).</p>



<p>In addition to <strong><em>LOGNAME</em></strong>, <strong><em>HOME</em></strong>, and <strong><em>SHELL</em></strong>, cron looks at the <strong><em>MAILTO</em></strong> variable if a mail needs to be send as a result of running any commands in that particular crontab.  If <strong><em>MAILTO</em></strong> is defined (and non-empty), mail is sent to the specified address.  If <strong><em>MAILTO</em></strong> is defined but empty (<strong><em>MAILTO</em></strong>=""), no mail is sent.  Otherwise, mail is sent to the owner of the crontab.  This option is useful if you decide to use <em>/bin/mail</em> instead of <em>/usr/lib/sendmail</em> as your mailer.  Note that<em> /bin/mail</em> does not provide aliasing and <strong><em>UUCP</em></strong> usually does not read its mail.  If <strong><em>MAILFROM</em></strong> is defined (and non-empty), it is used as the envelope sender address, otherwise, ``root'' is used.</p>



<p>By default, cron sends a mail using the <em>'Content-Type:</em>' header of '<em>text/plain</em>' with the '<em>charset=</em>' parameter set to the '<em>charmap/codeset</em>' of the locale in which crond is started up, i.e., either the default system locale, if no <strong><em>LC_*</em></strong> environment variables are set, or the locale specified by the <em><strong>LC_*</strong></em> environment variables.  Different character encodings can be used for mailing cron job outputs by setting the <strong><em>CONTENT_TYPE</em></strong> and <strong><em>CONTENT_TRANSFER_ENCODING</em></strong> variables in a crontab to the correct values of the mail headers of those names.</p>



<p>The <strong><em>CRON_TZ</em></strong> variable specifies the time zone specific for the cron table.  The user should enter a time according to the specified time zone into the table.  The time used for writing into a log file is taken from the local time zone, where the daemon is running.</p>



<p>The <strong><em>MLS_LEVEL</em></strong> environment variable provides support for multiple per-job SELinux security contexts in the same crontab.  By default, cron jobs execute with the default SELinux security context of the user that created the crontab file.  When using multiple security levels and roles, this may not be sufficient, because the same user may be running in different roles or in different security levels.</p>



<p>The <strong><em>RANDOM_DELAY</em></strong> variable allows delaying job startups by random amount of minutes with upper limit specified by the variable. The random scaling factor is determined during the cron daemon startup so it remains constant for the whole run time of the daemon.</p>



<p><strong>The time and date fields are:</strong></p>



<pre class="wp-block-code"><code>field          allowed values
-----          --------------
minute         0-59
hour           0-23
day of month   1-31
month          1-12 (or names, see below)
day of week    0-7 (0 or 7 is Sunday, or use names)</code></pre>



<p>A field may contain an asterisk (*), which always stands for <em>"first-last"</em>.</p>



<p>Ranges of numbers are allowed.  Ranges are two numbers separated with a <strong>hyphen</strong>.  The specified range is inclusive.  For example, <strong>8-11</strong> for an '<strong>hours</strong>' entry specifies execution at <strong>hours 8, 9, 10, and 11</strong>. The first number must be less than or equal to the second one.</p>



<p>Lists are allowed.  A list is a set of numbers (or ranges) separated by commas.  Examples: <em>"1,2,5,9", "0-4,8-12".</em></p>



<h2>EXAMPLE CRON FILE </h2>



<pre class="wp-block-code"><code># use /bin/sh to run commands, no matter what /etc/passwd says
SHELL=/bin/sh
# mail any output to `paul', no matter whose crontab this is
MAILTO=paul
#
CRON_TZ=Japan
# run five minutes after midnight, every day
5 0 * * *       $HOME/bin/daily.job >> $HOME/tmp/out 2>&amp;1
# run at 2:15pm on the first of every month -- output mailed to paul
15 14 1 * *     $HOME/bin/monthly
# run at 10 pm on weekdays, annoy Joe
0 22 * * 1-5    mail -s "It's 10pm" joe%Joe,%%Where are your kids?%
23 0-23/2 * * * echo "run 23 minutes after midn, 2am, 4am ..., everyday"
5 4 * * sun     echo "run at 5 after 4 every sunday"</code></pre>



<h2>Jobs in /etc/cron.d/</h2>



<p>The jobs in <strong>cron.d</strong> and <em>/etc/crontab</em> are system jobs, which are used usually for more than one user, thus, additionally the username is needed.  <strong><em>MAILTO</em></strong> on the first line is optional.</p>



<h2>EXAMPLE OF A JOB IN /etc/cron.d/job</h2>



<pre class="wp-block-code"><code>#login as root
#create job with preferred editor (e.g. vim)
MAILTO=root
* * * * * root touch /tmp/file</code></pre>



<h2>SELinux with multi level security (MLS)</h2>



<p>In a crontab, it is important to specify a security level by <strong><em>crontab -s</em></strong> or specifying the required level on the first line of the crontab. Each level is specified in <em>/etc/selinux/targeted/seusers</em>. When using crontab in the <strong><em>MLS</em></strong> mode, it is especially important to:</p>



<ul><li><em>check/change</em> the actual role,</li><li>set correct<strong> role for directory</strong>, which is used for <em>input/output</em>.</li></ul>



<h2>EXAMPLE FOR SELINUX MLS</h2>



<pre class="wp-block-code"><code># login as root
newrole -r sysadm_r
mkdir /tmp/SystemHigh
chcon -l SystemHigh /tmp/SystemHigh
crontab -e
# write in crontab file
MLS_LEVEL=SystemHigh
0-59 * * * * id -Z > /tmp/SystemHigh/crontest</code></pre>



<h2>FILES</h2>



<ul><li><strong>/etc/crontab</strong> main system crontab file.</li><li><strong>/var/spool/cron/</strong> a directory for storing crontabs defined by users.</li><li><strong>/etc/cron.d/</strong> a directory for storing system crontabs.</li></ul>



<h2>EXTENSIONS</h2>



<p>These special time specification "<em>nicknames</em>" which replace the 5 initial time and date fields, and are prefixed with the '@' character, are supported:</p>



<pre class="wp-block-code"><code>@reboot    :    Run once after reboot.
@yearly    :    Run once a year, ie.  "0 0 1 1 *".
@annually  :    Run once a year, ie.  "0 0 1 1 *".
@monthly   :    Run once a month, ie. "0 0 1 * *".
@weekly    :    Run once a week, ie.  "0 0 * * 0".
@daily     :    Run once a day, ie.   "0 0 * * *".
@hourly    :    Run once an hour, ie. "0 * * * *".</code></pre>

Name



Crontab - files used to schedule the execution of programs



Description



A crontab file contains instructions for the cron daemon in ...

What is Crontab? - TCMHACK

What is Crontab?

<p>Hey Guys, In this tutorial, we will learn how to upload files via ssh using terminal.</p>



<p>Uploading files via ssh required when you don't have any <strong>cPanel</strong> to work with like aws hosting which only provides you the <strong>SSH</strong>.</p>



<p>So we will be using the SCP (Secure Copy Protocal) for file transfer. Let's start.</p>



<h3>What is Secure Copy Protocal (SCP)</h3>



<p><strong>Secure copy protocol (SCP)</strong> is a means of securely transferring computer files between a local host and a remote host or between two remote hosts.It is based on the Secure Shell (SSH) protocol.</p>



<p>"SCP" commonly refers to both the Secure Copy Protocol and the program itself. According to OpenSSH developers in April 2019 the scp protocol is outdated, inflexible and not readily fixed; they recommend the use of more modern protocols like sftp and rsync for file transfer.</p>



<p>The <strong>SCP program</strong> is a software tool implementing the SCP protocol as a service daemon or client. It is a program to perform secure copying.</p>



<h4><strong>Syntax</strong></h4>



<p>Typically, a syntax of&nbsp;scp&nbsp;program&nbsp;is like the syntax of&nbsp;<strong>cp&nbsp;(copy)</strong>:</p>



<p>Copying file to host:</p>



<pre class="wp-block-code"><code>scp SourceFile user@host:directory/TargetFile</code></pre>



<p>Copying folder from host:</p>



<pre class="wp-block-code"><code>scp user@host:directory/SourceFile TargetFile
scp -r user@host:directory/SourceFolder TargetFolder</code></pre>



<p>Note that if the remote host uses a port other than the default of 22, it can be specified in the command. For example, copying a file from host:</p>



<pre class="wp-block-code"><code>scp -P 2222 user@host:directory/SourceFile TargetFile</code></pre>



<p><strong>If you're working with aws hosting then you must have to use the <em>key</em></strong></p>



<pre class="wp-block-code"><code>scp -i yourkey.pem user@host:directory/SourceFile TargetFile</code></pre>



<p><strong><em>Let's take an example:</em></strong></p>



<pre class="wp-block-code"><code>scp -i mykey.pem /var/www/html/myfile.sql ubuntu@google.com:/var/www/htmlmyfile.sql</code></pre>



<h2>Feels like watching?</h2>



<figure class="wp-block-embed is-type-video is-provider-youtube wp-block-embed-youtube wp-embed-aspect-16-9 wp-has-aspect-ratio"><div class="wp-block-embed__wrapper">
https://www.youtube.com/watch?v=C0ImnCTI1W8
</div></figure>

Hey Guys, In this tutorial, we will learn how to upload files via ssh using terminal.



Uploading files via ssh required when you don't have any...

How to upload files via ssh using scp on ubuntu - TCMHACK

How to upload files via ssh using scp on ubuntu

<h3 id="introduction">Introduction</h3>



<p>Redis is an in-memory key-value store known for its flexibility, performance, and wide language support. In this guide, we will demonstrate how to install and configure Redis on an Ubuntu 16.04 server.</p>



<h2 id="prerequisites">Prerequisites</h2>



<p>To complete this guide, you will need access to an Ubuntu 16.04 server. You will need a non-root user with <code>sudo</code> privileges to perform the administrative functions required for this process. You can learn how to set up an account with these privileges by following our <a href="https://www.digitalocean.com/community/tutorials/initial-server-setup-with-ubuntu-16-04">Ubuntu 16.04 initial server setup guide</a>.</p>



<p>When you are ready to begin, log in to your Ubuntu 16.04 server with your&nbsp;<code>sudo</code>&nbsp;user and continue below.</p>



<h2 id="install-the-build-and-test-dependencies">Install the Build and Test Dependencies</h2>



<p>In order to get the latest version of Redis, we will be compiling and installing the software from source. Before we download the code, we need to satisfy the build dependencies so that we can compile the software.</p>



<p>To do this, we can install the&nbsp;<code>build-essential</code>&nbsp;meta-package from the Ubuntu repositories. We will also be downloading the&nbsp;<code>tcl</code>&nbsp;package, which we can use to test our binaries.</p>



<p>We can update our local&nbsp;<code>apt</code>&nbsp;package cache and install the dependencies by typing:</p>



<pre class="wp-block-preformatted">sudo apt-get update
sudo apt-get install build-essential tcl
</pre>



<h2 id="download-compile-and-install-redis">Download, Compile, and Install Redis</h2>



<p>Next, we can begin to build Redis.</p>



<h3 id="download-and-extract-the-source-code">Download and Extract the Source Code</h3>



<p>Since we won’t need to keep the source code that we’ll compile long term (we can always re-download it), we will build in the&nbsp;<code>/tmp</code>&nbsp;directory. Let’s move there now:</p>



<pre class="wp-block-preformatted">cd /tmp
</pre>



<p>Now, download the latest stable version of Redis. This is always available at <a href="http://download.redis.io/redis-stable.tar.gz" target="_blank" rel="noreferrer noopener" aria-label=" (opens in a new tab)">a stable download URL</a>:</p>



<pre class="wp-block-preformatted">curl -O http://download.redis.io/redis-stable.tar.gz
</pre>



<p>Unpack the tarball by typing:</p>



<pre class="wp-block-preformatted">tar xzvf redis-stable.tar.gz
</pre>



<p>Move into the Redis source directory structure that was just extracted:</p>



<pre class="wp-block-preformatted">cd redis-stable
</pre>



<h3 id="build-and-install-redis">Build and Install Redis</h3>



<p>Now, we can compile the Redis binaries by typing:</p>



<pre class="wp-block-preformatted">make
</pre>



<p>After the binaries are compiled, run the test suite to make sure everything was built correctly. You can do this by typing:</p>



<pre class="wp-block-preformatted">make test
</pre>



<p>This will typically take a few minutes to run. Once it is complete, you can install the binaries onto the system by typing:</p>



<pre class="wp-block-preformatted">sudo make install
</pre>



<h2 id="configure-redis">Configure Redis</h2>



<p>Now that Redis is installed, we can begin to configure it.</p>



<p>To start off, we need to create a configuration directory. We will use the conventional&nbsp;<code>/etc/redis</code>&nbsp;directory, which can be created by typing:</p>



<pre class="wp-block-preformatted">sudo mkdir /etc/redis
</pre>



<p>Now, copy over the sample Redis configuration file included in the Redis source archive:</p>



<pre class="wp-block-preformatted">sudo cp /tmp/redis-stable/redis.conf /etc/redis
</pre>



<p>Next, we can open the file to adjust a few items in the configuration:</p>



<pre class="wp-block-preformatted">sudo nano /etc/redis/redis.conf
</pre>



<p>In the file, find the&nbsp;<code>supervised</code>&nbsp;directive. Currently, this is set to&nbsp;<code>no</code>. Since we are running an operating system that uses the systemd init system, we can change this to&nbsp;<code>systemd</code>:/etc/redis/redis.conf</p>



<pre class="wp-block-code"><code>. . .

# If you run Redis from upstart or systemd, Redis can interact with your
# supervision tree. Options:
#   supervised no      - no supervision interaction
#   supervised upstart - signal upstart by putting Redis into SIGSTOP mode
#   supervised systemd - signal systemd by writing READY=1 to $NOTIFY_SOCKET
#   supervised auto    - detect upstart or systemd method based on
#                        UPSTART_JOB or NOTIFY_SOCKET environment variables
# Note: these supervision methods only signal "process is ready."
#       They do not enable continuous liveness pings back to your supervisor.
supervised systemd

. . .</code></pre>



<p>Next, find the&nbsp;<code>dir</code>&nbsp;directory. This option specifies the directory that Redis will use to dump persistent data. We need to pick a location that Redis will have write permission and that isn’t viewable by normal users.</p>



<p>We will use the&nbsp;<code>/var/lib/redis</code>&nbsp;directory for this, which we will create in a moment:/etc/redis/redis.conf</p>



<pre class="wp-block-code"><code>. . .

# The working directory.
#
# The DB will be written inside this directory, with the filename specified
# above using the 'dbfilename' configuration directive.
#
# The Append Only File will also be created inside this directory.
#
# Note that you must specify a directory here, not a file name.
dir /var/lib/redis

. . .</code></pre>



<p>Save and close the file when you are finished.</p>



<h2 id="create-a-redis-systemd-unit-file">Create a Redis systemd Unit File</h2>



<p>Next, we can create a systemd unit file so that the init system can manage the Redis process.</p>



<p>Create and open the&nbsp;<code>/etc/systemd/system/redis.service</code>&nbsp;file to get started:</p>



<pre class="wp-block-preformatted">sudo nano /etc/systemd/system/redis.service
</pre>



<p>Inside, we can begin the&nbsp;<code>[Unit]</code>&nbsp;section by adding a description and defining a requirement that networking be available before starting this service:/etc/systemd/system/redis.service</p>



<pre class="wp-block-code"><code>[Unit]
Description=Redis In-Memory Data Store
After=network.target</code></pre>



<p>In the&nbsp;<code>[Service]</code>&nbsp;section, we need to specify the service’s behavior. For security purposes, we should not run our service as&nbsp;<code>root</code>. We should use a dedicated user and group, which we will call&nbsp;<code>redis</code>&nbsp;for simplicity. We will create these momentarily.</p>



<p>To start the service, we just need to call the&nbsp;<code>redis-server</code>&nbsp;binary, pointed at our configuration. To stop it, we can use the Redis&nbsp;<code>shutdown</code>&nbsp;command, which can be executed with the&nbsp;<code>redis-cli</code>&nbsp;binary. Also, since we want Redis to recover from failures when possible, we will set the&nbsp;<code>Restart</code>&nbsp;directive to “always”:/etc/systemd/system/redis.service</p>



<pre class="wp-block-code"><code>[Unit]
Description=Redis In-Memory Data Store
After=network.target

[Service]
User=redis
Group=redis
ExecStart=/usr/local/bin/redis-server /etc/redis/redis.conf
ExecStop=/usr/local/bin/redis-cli shutdown
Restart=always</code></pre>



<p>Finally, in the&nbsp;<code>[Install]</code>&nbsp;section, we can define the systemd target that the service should attach to if enabled (configured to start at boot):/etc/systemd/system/redis.service</p>



<pre class="wp-block-code"><code>[Unit]
Description=Redis In-Memory Data Store
After=network.target

[Service]
User=redis
Group=redis
ExecStart=/usr/local/bin/redis-server /etc/redis/redis.conf
ExecStop=/usr/local/bin/redis-cli shutdown
Restart=always

[Install]
WantedBy=multi-user.target</code></pre>



<p>Save and close the file when you are finished.</p>



<h2 id="create-the-redis-user-group-and-directories">Create the Redis User, Group and Directories</h2>



<p>Now, we just have to create the user, group, and directory that we referenced in the previous two files.</p>



<p>Begin by creating the&nbsp;<code>redis</code>&nbsp;user and group. This can be done in a single command by typing:</p>



<pre class="wp-block-preformatted">sudo adduser --system --group --no-create-home redis
</pre>



<p>Now, we can create the&nbsp;<code>/var/lib/redis</code>&nbsp;directory by typing:</p>



<pre class="wp-block-preformatted">sudo mkdir /var/lib/redis
</pre>



<p>We should give the&nbsp;<code>redis</code>&nbsp;user and group ownership over this directory:</p>



<pre class="wp-block-preformatted">sudo chown redis:redis /var/lib/redis
</pre>



<p>Adjust the permissions so that regular users cannot access this location:</p>



<pre class="wp-block-preformatted">sudo chmod 770 /var/lib/redis
</pre>



<h2 id="start-and-test-redis">Start and Test Redis</h2>



<p>Now, we are ready to start the Redis server.</p>



<h3 id="start-the-redis-service">Start the Redis Service</h3>



<p>Start up the systemd service by typing:</p>



<pre class="wp-block-preformatted">sudo systemctl start redis
</pre>



<p>Check that the service had no errors by running:</p>



<pre class="wp-block-preformatted">sudo systemctl status redis
</pre>



<p>You should see something that looks like this:</p>



<pre class="wp-block-code"><code>Output● redis.service - Redis Server
   Loaded: loaded (/etc/systemd/system/redis.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2016-05-11 14:38:08 EDT; 1min 43s ago
  Process: 3115 ExecStop=/usr/local/bin/redis-cli shutdown (code=exited, status=0/SUCCESS)
 Main PID: 3124 (redis-server)
    Tasks: 3 (limit: 512)
   Memory: 864.0K
      CPU: 179ms
   CGroup: /system.slice/redis.service
           └─3124 /usr/local/bin/redis-server 127.0.0.1:6379       

. . .</code></pre>



<h3 id="test-the-redis-instance-functionality">Test the Redis Instance Functionality</h3>



<p>To test that your service is functioning correctly, connect to the Redis server with the command-line client:</p>



<pre class="wp-block-preformatted">redis-cli
</pre>



<p>In the prompt that follows, test connectivity by typing:</p>



<pre class="wp-block-preformatted">127.0.0.1:6379> ping</pre>



<p>You should see:</p>



<pre class="wp-block-code"><code>Output: PONG</code></pre>



<p>Check that you can set keys by typing:</p>



<pre class="wp-block-preformatted">127.0.0.1:6379> set test "It's working!" </pre>



<pre class="wp-block-code"><code>Output: OK</code></pre>



<p>Now, retrieve the value by typing:</p>



<pre class="wp-block-preformatted">127.0.0.1:6379> get test</pre>



<p>You should be able to retrieve the value we stored:</p>



<pre class="wp-block-code"><code>Output: "It's working!"</code></pre>



<p>Exit the Redis prompt to get back to the shell:</p>



<pre class="wp-block-preformatted">127.0.0.1:6379> exit </pre>



<p>As a final test, let’s restart the Redis instance:</p>



<pre class="wp-block-preformatted">sudo systemctl restart redis
</pre>



<p>Now, connect with the client again and confirm that your test value is still available:</p>



<pre class="wp-block-preformatted">redis-cli
</pre>



<pre class="wp-block-preformatted">127.0.0.1:6379> get test </pre>



<p>The value of your key should still be accessible:</p>



<pre class="wp-block-code"><code>Output: "It's working!"</code></pre>



<p>Back out into the shell again when you are finished:</p>



<pre class="wp-block-preformatted">127.0.0.1:6379> exit </pre>



<h3 id="enable-redis-to-start-at-boot">Enable Redis to Start at Boot</h3>



<p>If all of your tests worked, and you would like to start Redis automatically when your server boots, you can enable the systemd service.</p>



<p>To do so, type:</p>



<pre class="wp-block-preformatted">sudo systemctl enable redis
</pre>



<pre class="wp-block-code"><code>OutputCreated symlink from /etc/systemd/system/multi-user.target.wants/redis.service to /etc/systemd/system/redis.service.</code></pre>

Introduction



Redis is an in-memory key-value store known for its flexibility, performance, and wide language support. In this guide, we will d...

How To Install and Configure Redis on Ubuntu 16.04 - TCMHACK

How To Install and Configure Redis on Ubuntu 16.04

<p>Moving files and directories is one of the most basic tasks you often need to perform on a Linux system.</p>



<p>In this tutorial, we will explain how to use the&nbsp;<code>mv</code>&nbsp;command to move files and directories.</p>



<h2 id="how-to-use-the-mv-command">How to Use the mv Command</h2>



<p>The&nbsp;<code>mv</code>&nbsp;command (short from move) is used to rename and move and files and directories from one location to another. The syntax for the&nbsp;<code>mv</code>&nbsp;command is as follows:</p>



<pre class="wp-block-code"><code>mv [OPTIONS] source destination</code></pre>



<p>The&nbsp;<code>source</code>&nbsp;can be one or more files or directories and&nbsp;<code>destination</code>&nbsp;can be a single file or directory.</p>



<ul><li>If you specify multiple files or directories as a <code>source</code>, the <code>destination</code>  must be a directory. In this case, the <code>source</code> files are moved to the target directory.</li><li>If you specify a single file as <code>source</code>, and the <code>destination</code> target is an existing directory then the file is moved to the specified directory.</li><li>If you specify a single file as <code>source</code>, and a single file as <code>destination</code> target then you’re renaming the file.</li><li>If the <code>source</code> is a directory and <code>destination</code> doesn’t, exist <code>source</code> will be renamed to <code>destination</code>, otherwise it be moved inside the <code>destination</code> directory.</li></ul>



<p>To move a file or directory you need to have write permissions on both <code>source</code> and <code>destination</code>. Otherwise, you will receive a permission denied error.</p>



<p>For example, to move the file&nbsp;<code>file1</code>&nbsp;from the current working directory to the&nbsp;<code>/tmp</code>&nbsp;directory you would run:</p>



<pre class="wp-block-code"><code>mv file1 /tmp</code></pre>



<p>To rename a file specify the destination file name:</p>



<pre class="wp-block-code"><code>mv file1 file2</code></pre>



<p>The command for moving directories is the same as when moving files. In the following example if the&nbsp;<code>dir2</code>&nbsp;directory exists the command will move&nbsp;<code>dir1</code>inside&nbsp;<code>dir2</code>. If&nbsp;<code>dir2</code>&nbsp;doesn’t exist,&nbsp;<code>dir1</code>&nbsp;will be renamed to&nbsp;<code>dir2</code>:</p>



<pre class="wp-block-code"><code>mv dir1 dir2</code></pre>



<h2 id="moving-multiple-files-and-directories">Moving Multiple Files and Directories</h2>



<p>To move multiple files and directories, specify the files you want to move as the source. For example to move the files&nbsp;<code>file1</code>&nbsp;and&nbsp;<code>file2</code>&nbsp;to the&nbsp;<code>dir1</code>&nbsp;directory you would type:</p>



<pre class="wp-block-code"><code>mv file1 file2 dir1</code></pre>



<p>The&nbsp;<code>mv</code>&nbsp;command also allows you to use pattern matching. For example, to copy all pdf files from the current directory to the&nbsp;<code>~/Documents</code>&nbsp;directory you would use:</p>



<pre class="wp-block-code"><code>mv *.pdf ~/Documents</code></pre>



<h2 id="mv-command-options">mv Command Options</h2>



<p>The <code>mv</code> command accepts options that affect default command behavior. In some Linux distributions <code>mv</code> may be an <strong>alias</strong> to the <code>mv</code> command with a custom set of options. For example in CentOS <code>mv</code> is an alias to <code>mv -i</code>. You can find whether <code>mv</code> is an alias using the <code>type</code> command:</p>



<pre class="wp-block-code"><code>type mv</code></pre>



<p>If&nbsp;<code>mv</code>&nbsp;is alias the output will look something like this:</p>



<pre class="wp-block-code"><code>mv is aliased to `mv -i'</code></pre>



<p>If you specify conflicting options, the option specified last takes precendence.</p>



<h3 id="prompt-before-overwriting">Prompt before overwriting</h3>



<p>By default if the destination file exists it will be overwritten. To prompt for confirmation use the&nbsp;<code>-i</code>&nbsp;option:</p>



<pre class="wp-block-code"><code>mv -i file1 /tmp</code></pre>



<pre class="wp-block-code"><code>mv: overwrite '/tmp/file1'?</code></pre>



<p>To overwrite the file type the character&nbsp;<code>y</code>&nbsp;or&nbsp;<code>Y</code>.</p>



<h3 id="force-overwriting">Force overwriting</h3>



<p>If you try to overwrite a read only file the&nbsp;<code>mv</code>&nbsp;command will prompt you whether you want to overwrite the file:</p>



<pre class="wp-block-code"><code>mv -i file1 /tmp</code></pre>



<pre class="wp-block-code"><code>mv: replace '/tmp/file1', overriding mode 0400 (r--------)? </code></pre>



<p>To avoid being prompted use the&nbsp;<code>-f</code>&nbsp;options:</p>



<pre class="wp-block-code"><code>mv -f file1 /tmp</code></pre>



<p>This option is especially useful when you need to overwrite multiple reed only file.</p>



<h3 id="do-not-overwrite-existing-files">Do not overwrite existing files</h3>



<p>The&nbsp;<code>-n</code>&nbsp;option tells&nbsp;<code>mv</code>&nbsp;never to overwrite any existing file:</p>



<pre class="wp-block-code"><code>mv -f file1 /tmp</code></pre>



<p>If a&nbsp;<code>file1</code>&nbsp;exists the command above will do nothing, otherwise it will copy the file to the&nbsp;<code>/tmp</code>&nbsp;directory.</p>



<h3 id="backing-up-files">Backing up files</h3>



<p>If the destination file exists you can create a backup of it using the&nbsp;<code>-b</code>&nbsp;option:</p>



<pre class="wp-block-code"><code>mv -b file1 /tmp</code></pre>



<p>The backup file will have the same name as the original file with a tilde (<code>~</code>) appended to it.</p>



<p>Use the <strong>ls command</strong> to verify that the backup was created:</p>



<pre class="wp-block-code"><code>ls /tmp/file1*</code></pre>



<pre class="wp-block-code"><code>/tmp/file1  /tmp/file1~</code></pre>



<h3 id="verbose-output">Verbose output</h3>



<p>Another option that can be useful is&nbsp;<code>-v</code>. When using this option the command will print the name of each moved file:</p>



<pre class="wp-block-code"><code>mv -i file1 /tmp</code></pre>



<pre class="wp-block-code"><code>renamed 'file1' -> '/tmp/file1'</code></pre>



<h2 id="conclusion">Conclusion</h2>



<p>By now you should have a good understanding of how to use the&nbsp;<code>mv</code>&nbsp;command to move files and directories. New Linux users who are intimidated by the command line can use the GUI file manager to move their files.</p>



<p>For more information about the <code>mv</code> command check the <a href="https://ss64.com/bash/mv.html" target="_blank" rel="noreferrer noopener" aria-label=" (opens in a new tab)">man page</a>.</p>



<p>If you have any question or feedback, feel free to leave a comment.<br></p>

Moving files and directories is one of the most basic tasks you often need to perform on a Linux system.



In this tutorial, we will explain how...

How to Move Files and Directories in Linux with the mv Command - TCMHACK

How to Move Files and Directories in Linux with the mv Command

<p>When working on the command line quite often you will need to create or edit text files. Two of the most powerful and popular used command line editors are Vim and Emacs. Both of them have a steep learning curve that can be intimidating to new users. For those who need a simple editor, there is nano.</p>



<p>GNU nano is an easy to use command line text editor for Unix and Linux operating systems. It includes all the basic functionality you’d expect from a regular text editor, like syntax highlighting, multiple buffers, search and replace with regular expression support, spellchecking, UTF-8 encoding, and more.</p>



<p>In this guide, we will cover the basics of using the nano editor including how to create and open a file, edit a file, save a file, search and replace text, cut and paste text, and more.</p>



<h2 id="installing-nano">Installing Nano</h2>



<p>Nano text editor is pre-installed on macOS and most Linux distros. To check if it is installed on your system type:</p>



<pre class="wp-block-code"><code>$ nano --version</code></pre>



<p>The output will look something like this:</p>



<pre class="wp-block-code"><code>Output:
GNU nano, version 2.9.3
(C) 1999-2011, 2013-2018 Free Software Foundation, Inc.
(C) 2014-2018 the contributors to nano
Email: nano@nano-editor.org	Web: https://nano-editor.org/</code></pre>



<p>If you don’t have nano installed on your system, you can install it using the package manager of your distribution.</p>



<h3 id="install-nano-on-ubuntu-and-debian">Install Nano on Ubuntu and Debian</h3>



<pre class="wp-block-code"><code>$ sudo apt install nano</code></pre>



<h3 id="install-nano-on-centos-and-fedora">Install Nano on CentOS and Fedora</h3>



<pre class="wp-block-code"><code>$ sudo yum install nano</code></pre>



<h2 id="opening-and-creating-files">Opening and Creating Files</h2>



<p>To open an existing file or to create a new file, type&nbsp;<code>nano</code>&nbsp;followed by the file name:</p>



<pre class="wp-block-code"><code>$ nano filename</code></pre>



<figure class="wp-block-image"><img src="http://ec2-13-127-91-65.ap-south-1.compute.amazonaws.com/wp-content/uploads/2019/07/nano-text-editor-screenshot-1024x554.jpg" alt="" class="wp-image-427"/></figure>



<p>This opens a new editor window and you can start editing the file.</p>



<p>At the bottom of the window, there is a list of the most basic command shortcuts to use with the nano editor.</p>



<p>All commands are prefixed with either&nbsp;<code>^</code>&nbsp;or&nbsp;<code>M</code>&nbsp;character. The caret symbol (<code>^</code>) represents the&nbsp;<code>Ctrl</code>&nbsp;key. For example, the&nbsp;<code>^J</code>&nbsp;commands mean to press the&nbsp;<code>Ctrl</code>&nbsp;and&nbsp;<code>J</code>&nbsp;keys at the same time. The letter&nbsp;<code>M</code>&nbsp;represents the&nbsp;<code>Alt</code>&nbsp;key.</p>



<p>You can get a list of all commands by typing&nbsp;<code>Ctrl+g</code>.</p>



<p>To be able to open a file you must have read permissions to the file.</p>



<p>If you want to open a file with the cursor on a specific line and character use the following syntax:</p>



<pre class="wp-block-code"><code>$ nano +line_number,character_number filename</code></pre>



<p>If you omit the&nbsp;<code>character_number</code>&nbsp;the cursor will be positioned on the first character.</p>



<h2 id="editing-files">Editing Files</h2>



<p>Unlike vi, nano is a modeless editor which means that you can start typing and editing the text immediately after opening the file.</p>



<p>To move the cursor to a specific line and character number, use the&nbsp;<code>Ctrl+_</code>command. The menu on the bottom of the screen will change. Enter the number(s) in the “Enter line number, column number:” field and hit&nbsp;<code>Enter</code>.</p>



<h3 id="searching-and-replacing">Searching and replacing</h3>



<p>To search for a text hit&nbsp;<code>Ctrl+w</code>, type in the search term, and press&nbsp;<code>Enter</code>. The cursor will move to the first match. To move to the next match, press&nbsp;<code>Alt+w</code>.</p>



<p>If you want to search and replace, press&nbsp;<code>Ctrl+\</code>. Enter the search term and the text to be replaced with. The editor will move to the first match and ask you whether to replace it. After hitting&nbsp;<code>Y</code>&nbsp;or&nbsp;<code>N</code>&nbsp;it will move to the next match. Pressing&nbsp;<code>A</code>&nbsp;will replace all matches.</p>



<h3 id="copping-cutting-and-pasting">Copping, cutting, and pasting</h3>



<p>To select text move the cursor to the beginning of the text and press&nbsp;<code>Alt+a</code>. This will set a selection mark. Move the cursor to the end of the text you want to select using the arrow keys. The selected text will be highlighted. If you want to cancel the selection press&nbsp;<code>Ctrl+6</code></p>



<p>Copy the selected text to the clipboard using the&nbsp;<code>Alt+6</code>&nbsp;command.&nbsp;<code>Ctrl+k</code>&nbsp;will cut the selected text.</p>



<p>If you want to cut whole lines simply move the cursor to the line and press&nbsp;<code>Ctrl+k</code>. You can cut multiple lines by hitting&nbsp;<code>Ctrl+k</code>&nbsp;several times.</p>



<p>To paste the text move the cursor to where you want to put the text and press&nbsp;<code>Ctrl+u</code>.</p>



<h2 id="saving-and-exiting">Saving and Exiting</h2>



<p>To save the changes you’ve made to the file, press&nbsp;<code>Ctrl+o</code>. If the file doesn’t already exist, it will be created once you save it.</p>



<p>If you want to exit nano press&nbsp;<code>Ctrl+x</code>. If there are unsaved changes you’ll be asked whether you want to save the changes.</p>



<p>To save the file you must have at write permissions to the file. If you are <strong>creating a new file</strong> you need to have write permission to the directory where the file will be created.</p>



<h2 id="customizing-nano-nanorc">Customizing Nano (nanorc)</h2>



<p>When nano is launched it reads its configuration parameters from the system-wide configuration file&nbsp;<code>/etc/nanorc</code>&nbsp;and from the user-specific files&nbsp;<code>~/.config/nano/nanorc</code>&nbsp;and&nbsp;<code>~/.nanorc</code>&nbsp;if the files are present.</p>



<p>Options specified in the user file take precedence over the global options.</p>



<p>Visit the <strong>nanorc</strong> page for a complete list of all available option.</p>



<h3 id="syntax-highlighting">Syntax Highlighting</h3>



<p>Nano ships with syntax highlighting rules for most popular file types. On most Linux systems the syntax files are stored in the&nbsp;<code>/usr/share/nano</code>&nbsp;directory and included by default in the&nbsp;<code>/etc/nanorc</code>&nbsp;configuration file.<br></p>



<pre class="wp-block-code"><code>include "/usr/share/nano/*.nanorc"</code></pre>



<p>The easiest option to enable highlighting for a new file type, is to add the syntax highlighting rules file to the&nbsp;<code>/usr/share/nano</code>&nbsp;directory.</p>



<h2 id="set-nano-as-the-default-text-editor">Set Nano as the Default Text Editor</h2>



<p>By default on most Linux systems, the default text editor for commands such as <code>visudo</code> and <a href="https://linuxize.com/post/scheduling-cron-jobs-with-crontab/"><code>crontab</code></a> is set to vi. To use nano as the default text editor you need to change the <code>VISUAL</code> and <code>EDITOR</code> <strong>environment variables.</strong></p>



<p>Bash users can export the variables in the&nbsp;<code>~/.bashrc</code>&nbsp;file:</p>



<pre class="wp-block-code"><code>export VISUAL=nano
export EDITOR="$VISUAL"</code></pre>



<h2 id="basic-nano-usage">Basic Nano Usage</h2>



<p>Below are the most basic steps for getting started with nano:</p>



<ol><li>On the command prompt, type&nbsp;<code>nano</code>&nbsp;followed by the filename.</li><li>Edit the file as required.</li><li>Use the&nbsp;<code>Ctrl-x</code>&nbsp;command to save and exit the text editor.</li></ol>



<h2 id="conclusion">Conclusion</h2>



<p>In this tutorial, we have shown you how to use Gnu nano text editor. It is a popular text editor among Linux users and has a small learning curve.</p>



<p>For more information about Gnu Nano visit the official <a href="https://www.nano-editor.org/docs.php" target="_blank" rel="noreferrer noopener" aria-label=" (opens in a new tab)">nano documentation</a>page.</p>

When working on the command line quite often you will need to create or edit text files. Two of the most powerful and popular used command line e...

How to Use Nano, the Command Line Text Editor in Linux - TCMHACK

How to Use Nano, the Command Line Text Editor in Linux

<p><a href="https://getcomposer.org/" target="_blank" rel="noreferrer noopener" aria-label=" (opens in a new tab)">Composer</a> is a dependency manager for PHP (similar to npm for Node.js or pip for Python). Composer will pull in all the required PHP packages your project depends on and manage them for you.</p>



<p>In this tutorial, we’ll show you how to install and use Composer on an Ubuntu 18.04 machine. The same steps can be used for Ubuntu 16.04.</p>



<h2 id="prerequisites">Prerequisites</h2>



<p>Before continuing with this tutorial, make sure you are logged in as a&nbsp;user with sudo privileges&nbsp;and you have&nbsp;PHP installed on your Ubuntu 18.04&nbsp;system.</p>



<h2 id="installing-php-composer">Installing PHP Composer</h2>



<p>If you are in a hurry and you don’t want to verify the file integrity scroll down to the&nbsp;<strong>Installing Composer - Quick Way</strong>&nbsp;section.</p>



<p>To install Composer on your Ubuntu system, perform the following steps:</p>



<p><strong>01. Before downloading and installing Composer, first update the packages index and install the necessary requirements:</strong></p>



<pre class="wp-block-code"><code>sudo apt update
sudo apt install wget php-cli php-zip unzip</code></pre>



<p><strong>02. Now that we have php cli installed on our machine, we can download the composer installer with:</strong></p>



<pre class="wp-block-code"><code>php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"</code></pre>



<p>The command above will download the&nbsp;<code>composer-setup.php</code>&nbsp;file in the current working directory.</p>



<p><strong>03. Next, we need to verify the data integrity of the script by comparing the script </strong><code><strong>SHA-384</strong></code><strong> hash with the latest installer hash found on the <a href="https://composer.github.io/pubkeys.html" target="_blank" rel="noreferrer noopener" aria-label=" (opens in a new tab)">Composer Public Keys / Signatures</a> page.</strong></p>



<p>We will use the following&nbsp;wget command&nbsp;to download the expected signature of the latest Composer installer from the Composer’s Github page and store it in a variable named&nbsp;<code>HASH</code>:</p>



<pre class="wp-block-code"><code>HASH="$(wget -q -O - https://composer.github.io/installer.sig)"</code></pre>



<p>Now run the following command to verify that the installation script is not corrupted:</p>



<pre class="wp-block-code"><code>php -r "if (hash_file('SHA384', 'composer-setup.php') === '$HASH') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"</code></pre>



<p>If the hashes match, you will see the following output:</p>



<pre class="wp-block-code"><code>Output:
Installer verified</code></pre>



<p>If the hashes don’t match you will see&nbsp;<code>Installer corrupt</code>. In this case you will need to redownload the Composer installation script and double check the value of the&nbsp;<code>$HASH</code>&nbsp;variable with&nbsp;<a href="https://linuxize.com/post/echo-command-in-linux-with-examples/"><code>echo $HASH</code></a>. Once the installer is verified, you can continue with the next step.</p>



<p><strong>04. The following command will install Composer in the </strong><code><strong>/usr/local/bin</strong></code><strong>directory:</strong></p>



<pre class="wp-block-code"><code>sudo php composer-setup.php --install-dir=/usr/local/bin --filename=composer</code></pre>



<pre class="wp-block-code"><code>Output
All settings correct for using Composer
Downloading...

Composer (version 1.8.5) successfully installed to: /usr/local/bin/composer
Use it: php /usr/local/bin/composer</code></pre>



<p>The&nbsp;<code>composer</code>&nbsp;is installed as a system-wide command and it will be available for all users.</p>



<p><strong>05. The last step is to verify the installation:</strong></p>



<pre class="wp-block-code"><code>$ composer</code></pre>



<p>The command above, will print the Composer’s version, commands and arguments.</p>



<pre class="wp-block-code"><code>Output
______
/ ____/___  ____ ___  ____  ____  ________  _____
/ /   / __ \/ __ `__ \/ __ \/ __ \/ ___/ _ \/ ___/
/ /___/ /_/ / / / / / / /_/ / /_/ (__  )  __/ /
\____/\____/_/ /_/ /_/ .___/\____/____/\___/_/
                    /_/
Composer version 1.8.5 2019-04-09 17:46:47

Usage:
    command [options] [arguments]</code></pre>

Composer is a dependency manager for PHP (similar to npm for Node.js or pip for Python). Composer will pull in all the required PHP packages your...