Display brightness level in i3status bar

I’ve been using Linux for a long time, but I was never entirely happy with the desktop environment options available. Until last year, Xfce was the closest to what I consider a good compromise between features and performance. Then I found i3, an amazing piece of software that changed my life.

i3 is a tiling window manager. The goal of a window manager is to control the appearance and placement of windows in a windowing system. Window managers are often used as part a full-featured desktop environment (such as GNOME or Xfce), but some can also be used as standalone applications.

i3status don’t have an option to display brightness level by default. But by tweaking some configuration we can easily achieve this.

Follow this method

  1. copy the script to /usr/local/bin



# Authors:
# - Moritz Warning <[email protected]> (2016)
# - Zhong Jianxin <[email protected]> (2014)
# - Akhil Jalagam <[email protected]> (2019)
# See file LICENSE at the project root directory for license information.
# i3status.conf should contain:
# general {
#   output_format = i3bar
# }
# i3 config looks like this:
# bar {
#   status_command exec /usr/share/doc/i3status/contrib/net-speed.sh
# }
# Single interface:
# ifaces="eth0"
# Multiple interfaces:
# ifaces="eth0 wlan0"

# Auto detect interfaces
#ifaces=$(ls /sys/class/net | grep -E '^(eth|wlan|enp|wlp)')
ifaces="enp2s0 wlp3s0"


readable() {
  local bytes=$1
  local kib=$(( bytes >> 10 ))
  if [ $kib -lt 0 ]; then
    echo "? K"
  elif [ $kib -gt 1024 ]; then
    local mib_int=$(( kib >> 10 ))
    local mib_dec=$(( kib % 1024 * 976 / 10000 ))
    if [ "$mib_dec" -lt 10 ]; then
    echo "${mib_int}.${mib_dec} M"
    echo "${kib} K"

update_rate() {
  local time=$(date +%s)
  local rx=0 tx=0 tmp_rx tmp_tx

  for iface in $ifaces; do
    read tmp_rx < "/sys/class/net/${iface}/statistics/rx_bytes"
    read tmp_tx < "/sys/class/net/${iface}/statistics/tx_bytes"
    rx=$(( rx + tmp_rx ))
    tx=$(( tx + tmp_tx ))

  local interval=$(( $time - $last_time ))
  if [ $interval -gt 0 ]; then
    rate="$(readable $(( (rx - last_rx) / interval )))↓ $(readable $(( (tx - last_tx) / interval )))↑"
  # show brightness
  brightness=$(cat /sys/class/backlight/intel_backlight/brightness)


i3status | (read line && echo "$line" && read line && echo "$line" && read line && echo "$line" && update_rate && while :
  read line
  echo ",[{\"full_text\":\"${rate} | Sun: $(($brightness/75))% \" },${line#,\[}" || exit 1

In the above script you can change /sys/class/backlight/intel_backlight/brightness based on your backlight model.

2. update i3 config with the following

# control brightness
bindsym XF86MonBrightnessUp exec intelbacklight -inc 500 # increase screen brightness
bindsym XF86MonBrightnessDown exec intelbacklight -dec 500 # decrease screen brightness

# status bar
bar {
        status_command  /usr/local/bin/net-speed-and-brightness.sh

Now reload the i3 config using Mod+Shift+r

Finally, you will see the net speed and brightness in status bar

If you don’t want to see net speed just remove {rate} from the echo command in above script

What is DevOps?


1. Definition from Wikipedia:

DevOps (a clipped compound of “development” and “operations”) is a set of software development practices[failed verification] that combines software development (Dev) with information technology operations (Ops) to shorten the systems development life cycle while delivering features, fixes, and updates frequently in close alignment with business objectives.

2. Definition from Webopedia

DevOps (development and operations) is an enterprise software development phrase used to mean a type of agile relationship between development and IT operations. The goal of DevOps is to change and improve the relationship by advocating better communication and collaboration between these two business units.

What is DevOps?

  1. DevOps is a culture that is followed by many big organizations. It is a combination of Development (software development) and Operations (software productions/IT operations).
  2. DevOps is an extended version of the Agile methodology. It is neither a tool or any technology, it is a culture or concept of behavior.
  3. DevOps defines a set of practices that are designed to overcome the communication and collaboration gap between the development, QA, and Operations team. It includes a Continuous Integration process with automated deployment.
  4. DevOps practices encourage the speed of delivering applications and services in the market.
  5. DevOps consists of 4 basic continuous processes in DevOps as follows:
  • Continuous Integration
  • Continuous Delivery
  • Continuous Testing
  • Continuous Monitoring

DevOps Life-cycle

i. Development
> In this DevOps stage the development of software takes place constantly. In this phase, the entire development process is separated into small development cycles. This benefits the DevOps team to speed up software development and delivery process.
ii. Testing
> QA team use tools like Selenium to identify and fix bugs in the new piece of code.
iii. Integration
> In this stage, new functionality is integrated with the prevailing code, and testing takes place. Continuous development is only possible due to continuous integration and testing.
iv. Deployment
> In this phase, the deployment process takes place continuously. It is performed in such a manner that any changes made any time in the code, should not affect the functioning of high traffic applications.
v. Monitoring
> In this phase, the operation team will take care of the inappropriate system behavior or bugs that are found in production.

Few of the benefits of DevOps are as follow

  • Speed
  • Rapid Delivery
  • Reliability
  • Scale
  • Improved collaboration
  • Security

The following are DevOps best practices

  • Continuous Integration
  • Continuous Delivery
  • Micro-services
  • Infrastructure as Code
  • Monitoring and Logging
  • Communication and Collaboration

storing multiple users and hosts in .my.cnf(MySQL)

When you run MySQL commands MySQL, mysqlcheck, mysqdump and psql, psqldump, etc; they will pick username & password from this file if you do not provide them as argument (-u and -p). It can save you time.

Of course, if you specify username and password explicitly as part of the command’s arguments, they will be used.

.my.cnf ( for MySQL client )

[clienthost1]   # Note: client + host1

Mail server ports

This article explains the most commonly used Email protocols on the internet – POP3, IMAP, and SMTP

  • SMTP 25, 2525
  • SMTP-SSL/TLS 587,465
  • IMAP 143
  • IMAP-SSL/TLS 993
  • POP3 110
  • POP3-SSL/TLS 995

587 vs. 465
These port assignments are specified by the Internet Assigned Numbers Authority (IANA):

Port 587: [SMTP] Message submission (SMTP-MSA), a service that accepts submission of email from email clients (MUAs). Described in RFC 6409.

Port 465: URL Rendezvous Directory for SSM (entirely unrelated to email)
Historically, port 465 was initially planned for the SMTPS encryption and authentication “wrapper” over SMTP, but it was quickly deprecated (within months, and over 15 years ago) in favour of STARTTLS over SMTP (RFC 3207). Despite that fact, there are probably many servers that support the deprecated protocol wrapper, primarily to support older clients that implemented SMTPS. Unless you need to support such older clients, SMTPS and its use on port 465 should remain nothing more than a historical footnote.

Quick Install latest git from source


wget https://github.com/git/git/archive/master.zip
unzip master.zip && rm master.zip
cd master
make configure
./configure --prefix=/usr
make install

PHP 7 Installation in CentOS 7

PHP installation script

yum install -y http://rpms.remirepo.net/enterprise/remi-release-7.rpm
yum install -y yum-utils
# yum-config-manager --enable remi-php70
# yum-config-manager --enable remi-php71
# yum-config-manager --enable remi-php72
yum-config-manager --enable remi-php73
yum -y install php # php-mcrypt php-cli php-gd php-curl php-mysql php-ldap php-zip php-fileinfo 
php -v

storing multiple users and hosts in .pgpass(psql)

When you run MySQL commands MySQL, mysqlcheck, mysqdump and psql, psqldump etc; they will pick username & password from this file if you do not provide them as argument (-u and -p). It can save you time.

Of course, if you specify username and password explicitly as part of the command’s arguments, they will be used.

.pgpass ( for psql client )


custom fail2ban filters

fail2Ban is a very handy tool to prevent a lot of unwanted traffic from consuming bandwidth on your servers. It’s a very small and relatively simple IDS Type Tool that comes with some predefined Filters to automatically lockout potentially dangerous or bandwidth-consuming type attacks.

Creating a Custom Filter

badagents = 360Spider|ZmEu|Auto Spider 1.0|zgrab/[0-9]*\.[0-9a-zA-Z]*|Wget\(.*\)|MauiBot.*
failregex = ^.+?:\d+ <HOST> -.*"(GET|POST|HEAD).*HTTP.*(?:%(badagents)s)"$
ignoreregex =


fail2ban-regex /path-to-samples/sample.log /etc/fail2ban/filter.d/custom.conf

Jail example

enabled  = true
logpath  = /var/log/apache*/access.log
action   = iptables-ipset-proto4[name=Custom, port=1010, protocol=tcp]
findtime = 86400
bantime  = -1
maxretry = 1