Linux Blimp

PXE or Preboot eXecution Environment is a server-client mechanism which instructs a client machine to boot form network.

In this guide we’ll show how to install Ubuntu Server via a PXE server with local HTTP sources mirrored from Ubuntu server ISO image via Apache web server. The PXE server used in this tutorial is Dnsmasq Server.

Requirements:

1. Ubuntu Server 16.04 or 17.04 Installation
2. A network interface configured with Static IP address
3. Ubuntu Server 16.04 or 17.04 ISO image

Step 1: Install and Configure DNSMASQ Server

1. In order to setup the PXE server, on the first step login with the root account or an account with root privileges and install Dnsmasq package in Ubuntu by issuing the following command.

# apt install dnsmasq

2. Next, backup dnsmasq main configuration file and then start editing the file with the following configurations.

# mv /etc/dnsmasq.conf /etc/dnsmasq.conf.backup
# nano /etc/dnsmasq.conf

Add the following configuration to dnsmasq.conf file.

interface=ens33,lo
bind-interfaces
domain=mypxe.local

dhcp-range=ens33,192.168.1.230,192.168.1.253,255.255.255.0,1h
dhcp-option=3,192.168.1.1
dhcp-option=6,192.168.1.1
dhcp-option=6,8.8.8.8
server=8.8.4.4
dhcp-option=28,10.0.0.255
dhcp-option=42,0.0.0.0

dhcp-boot=pxelinux.0,pxeserver,192.168.1.14

pxe-prompt="Press F8 for menu.", 2
pxe-service=x86PC, "Install Ubuntu 16.04 from network server 192.168.1.14", pxelinux
enable-tftp
tftp-root=/srv/tftp

On the above configuration file replace the following lines accordingly.

• interface Replace with your own machine network interface.
• domain – Replace it with your domain name.
• dhcp-range – Define your own network range for DHCP to allocate IPs to this network segment and how long should an IP address for a client should be granted.
• dhcp-option=3 – Your Gateway IP.
• dhcp-option=6 DNS Server IPs – several DNS IPs can be defined.
• server – DNS forwarder IPs Address.
• dhcp-option=28 – Your network broadcast address.
• dhcp-option=42 – NTP server – use 0.0.0.0 Address is for self-reference.
• dhcp-boot – the pxe boot file and the IP address of the PXE server (here pxelinux.0 and IP address of the same machine).
• pxe-prompt – Uses can hit F8 key to enter PXE menu or wait 2 seconds before automatically switching to PXE menu.
• pxe=service – Use x86PC for 32-bit/64-bit architectures and enter a menu description prompt under string quotes. Other values types can be: PC98, IA64_EFI, Alpha, Arc_x86, Intel_Lean_Client, IA32_EFI, BC_EFI, Xscale_EFI and X86-64_EFI.
• enable-tftp – Enables the build-in TFTP server.
• tftp-root – the system path for net boot files.

3. Also, after you’ve finished editing the dnsmasq configuration file, create the directory for the PXE netboot files by issuing the below command and restart dnsmasq daemon to apply changes. Check dnsmasq service status to see if it has been started.

# mkdir /srv/tftp
# systemctl restart dnsmasq.service
# systemctl status dnsmasq.service

Step 2: Install TFTP Netboot Files

4. On the next step grab the latest version of Ubuntu server ISO image for 64-bit architecture by issuing the following command.

# wget http://releases.ubuntu.com/16.04/ubuntu-16.04.3-server-amd64.iso

5. After Ubuntu server ISO has been downloaded, mount the image in /mnt directory and list the mounted directory content by running the below commands.

# mount -o loop ubuntu-16.04.3-desktop-amd64.iso /mnt/
# ls /mnt/

6. Next, copy the netboot files from Ubuntu mounted tree to tftp system path by issuing the below command. Also, list tftp system path to see the copied files.

# cp -rf /mnt/install/netboot/* /srv/tftp/
# ls /srv/tftp/

Step 3: Prepare Local Installation Source Files

7. The local network installation sources for Ubuntu server will be provided via HTTP protocol. First, install, start and enable Apache web server by issuing the following commands.

# apt install apache2
# systemctl start apache2
# systemctl status apache2
# systemctl enable apache2

8. Then, copy the content of the mounted Ubuntu DVD to Apache web server web root path by executing the below commands. List the content of Apache web root path to check if Ubuntu ISO mounted tree has been completely copied.

# cp -rf /mnt/* /var/www/html/
# ls /var/www/html/

9. Next, open HTTP port in firewall and navigate to your machine IP address via a browser (http://192.168.1.14/ubuntu) in order to test if you can reach sources via HTTP protocol.

# ufw allow http

Step 4: Setup PXE Server Configuration File

10. In order to be able to pivot the rootfs via PXE and local sources, Ubuntu needs to be instructed via a preseed file. Create the following local-sources.seed file in your web server document root path with the following content.

# nano /var/www/html/ubuntu/preseed/local-sources.seed

Add following line to local-sources.seed file.

d-i live-installer/net-image string http://192.168.1.14/ubuntu/install/filesystem.squashfs

Here, make sure you replace the IP address accordingly. It should be the IP address where web resources are located. In this guide the web sources, the PXE server and TFTP server are hosted on the same system. In a crowded network you might want to run PXE, TFTP and web services on separate machines in order to improve PXE network speed.

11. A PXE Server reads and executes configuration files located in pxelinux.cfg TFTP root directory in this order: GUID files, MAC files and default file.

The directory pxelinux.cfg is already created and populated with the required PXE configuration files because we’ve earlier copied the netboot files from Ubuntu mounted ISO image.

In order to add the above preseed statement file to Ubuntu installation label in PXE configuration file, open the following file for editing by issuing the below command.

# nano /srv/tftp/ubuntu-installer/amd64/boot-screens/txt.cfg

In Ubuntu PXE txt.cfg configuration file replace the following line as illustrated in the below excerpt.

append auto=true url=http://192.168.1.14/ubuntu/preseed/local-sources.seed vga=788 initrd=ubuntu-installer/amd64/initrd.gz --- quiet

The /srv/tftp/ubuntu-installer/amd64/boot-screens/txt.cfg file should have the following global content:

default install
label install
	menu label ^Install Ubuntu 16.04 with Local Sources
	menu default
	kernel ubuntu-installer/amd64/linux
	append auto=true url=http://192.168.1.14/ubuntu/preseed/local-sources.seed vga=788 initrd=ubuntu-installer/amd64/initrd.gz --- quiet 
label cli
	menu label ^Command-line install
	kernel ubuntu-installer/amd64/linux
	append tasks=standard pkgsel/language-pack-patterns= pkgsel/install-language-support=false vga=788 initrd=ubuntu-installer/amd64/initrd.gz --- quiet

12. In case you want to add the preseed url statement to Ubuntu Rescue menu, open the below file and make sure you update the content as illustrated in the below example.

# nano /srv/tftp/ubuntu-installer/amd64/boot-screens/rqtxt.cfg

Add the followng configuration to rqtxt.cfg file.

label rescue
	menu label ^Rescue mode
	kernel ubuntu-installer/amd64/linux
	append auto=true url=http://192.168.1.14/ubuntu/preseed/local-sources.seed vga=788 initrd=ubuntu-installer/amd64/initrd.gz rescue/enable=true --- quiet

The important line you should update is url=http://192.168.1.14/ubuntu/preseed/local-sources.seed which specifies the URL address where the pressed file is located in your network.

13. Finally, open Ubuntu pxe menu.cfg file and comment the first three lines in order to expand the PXE boot screen as illustrated in the below screenshot.

# nano /srv/tftp/ubuntu-installer/amd64/boot-screens/menu.cfg

Comment these three following lines.

#menu hshift 13
#menu width 49
#menu margin 8

Step 5: Open Firewall Ports in Ubuntu

14. Execute netstat command with root privileges to identify dnsmasq, tftp and web open ports in listening state on your server as illustrated in the below excerpt.

# netstat -tulpn

15. After you’ve identified all required ports, issue the below commands to open the ports in ufw firewall.

# ufw allow 53/tcp
# ufw allow 53/udp
# ufw allow 67/udp
# ufw allow 69/udp
# ufw allow 4011/udp

Step 6: Install Ubuntu with Local Sources via PXE

16. To install Ubuntu server via PXE and use the local network installation sources, reboot your machine client, instruct the BIOS to boot from network and at the first PXE menu screen choose the first option as illustrated in the below images.

17. The installation procedure should be performed as usual. When the installer reaches the Ubuntu archive mirror country setup, use the up keyboard arrow to move to the first option, which says: enter information manually.

18. Press [enter] key to update this option, delete the mirror string and add the IP address of the web server mirror sources and press enter to continue as illustrated in the below image.

http://192.168.1.14

19. On the next screen, add your mirror archive directory as shown below and press enter key to continue with the installation process and usually.

/ubuntu

20. In case you want to see information about what packages are downloaded from your network local mirror, press [CTRL+ALT+F2] keys in order to change machine virtual console and issue the following command.

# tail –f /var/log/syslog

21. After the installation of the Ubuntu server finishes, login to the newly installed system and run the following command with root privileges in order to update the repositories packages from local network sources to official Ubuntu mirrors.

The mirrors needs to be changed in order to update the system using the internet repositories.

$ sudo sed –i.bak ‘s/192.168.1.14/archive.ubuntu.com/g’ /etc/apt/sources.list

Assure you replace the IP address according to the IP address of your own web local sources.

That’s all! You can now update your Ubuntu server system and install all required software. Installing Ubuntu via PXE and a local network source mirror can improve the installation speed and can save internet bandwidth and costs in case of deploying a large number of servers in a short period of time at your premises.

Source

In order to protect sensitive data extraction from servers by users who have physical access to machines, it’s a best practice to disable all USB storage support in Linux kernel.

In order to disable USB storage support, we first need to identify if the storage driver is loaded into Linux kernel and the name of the driver (module) responsible with storage driver.

Run the lsmod command to list all loaded kernel drivers and filter the output via grep command with the search string “usb_storage”.

# lsmod | grep usb_storage

From lsmod command, we can see that the sub_storage module is in use by UAS module. Next, unload both USB storage modules from kernel and verify if the removal has been successfully completed, by issuing the below commands.

# modprobe -r usb_storage
# modprobe -r uas
# lsmod | grep usb

Next, list the content of the current runtime kernel usb storage modules directory by issuing the below command and identify the usb-storage driver name. Usually this module should be named usb-storage.ko.xz or usb-storage.ko.

# ls /lib/modules/`uname -r`/kernel/drivers/usb/storage/

In order to block USB storage module form loading into kernel, change directory to kernel usb storage modules path and rename the usb-storage.ko.xz module to usb-storage.ko.xz.blacklist, by issuing the below commands.

# cd /lib/modules/`uname -r`/kernel/drivers/usb/storage/
# ls
# mv usb-storage.ko.xz usb-storage.ko.xz.blacklist

In Debian based Linux distributions, issue the below commands to block usb-storage module from loading into Linux kernel.

# cd /lib/modules/`uname -r`/kernel/drivers/usb/storage/ 
# ls
# mv usb-storage.ko usb-storage.ko.blacklist

Now, whenever you plug-in a USB storage device, the kernel will be fail to load the storage device driver intro kernel. To revert changes, just rename the usb module blacklisted back to its old name.

# cd /lib/modules/`uname -r`/kernel/drivers/usb/storage/
# mv usb-storage.ko.xz.blacklist usb-storage.ko.xz

However, this method applies only to runtime kernel modules. In case you want to blacklist USB storage modules form all available kernels in the system, enter each kernel module directory version path and rename the usb-storage.ko.xz to usb-storage.ko.xz.blacklist.

Source

For recording Desktop screen there are a bunch of software’s available on the web, but have you ever thought about recording your Terminal? Well, it’s very much possible thanks to this nifty little program called Showterm.

What is Showterm?

Showterm is an open source terminal record and upload application that lets you easy to record how-to in your terminal. It will record all your terminal activity in text-base and upload to showterm.io as a video and then generates a link for you to share with your team-mates or embed it in your website as an iframe. Here’s an example of Demo:

Installation of Showterm in Linux

You can install showterm tool using two different methods. The recommended way is to use ruby, if you’ve rubycorrectly installed and configured on your system, then you can install it using gem command. If ruby doesn’t installed, you can install it using following commands.

On Debian/Ubuntu/Linux Mint

# sudo apt-get install ruby rubygems
# sudo gem install showterm

Sample Output

[sudo] password for tecmint: 
Fetching: showterm-0.5.0.gem (100%)
Building native extensions.  This could take a while...
Successfully installed showterm-0.5.0
1 gem installed
Installing ri documentation for showterm-0.5.0...
Installing RDoc documentation for showterm-0.5.0...

On RHEL/CentOS/Fedora

# yum install ruby rubygems
# gem install showterm

Sample Output

Building native extensions.  This could take a while...
Successfully installed showterm-0.5.0
1 gem installed
Installing ri documentation for showterm-0.5.0...
Installing RDoc documentation for showterm-0.5.0...

If your system does not have ruby configured correctly, you can install showterm in your bin directory with the following commands.

$ curl showterm.io/showterm > ~/bin/showterm
$ chmod +x ~/bin/showterm

How to Use Showterm

The syntax to start recording is “showterm [program to run]“. If you omit the program to run and just type in “showterm“.

# showterm

It’ll start recording your shell. Once you are done recording, you can stop it by typing in either exit or “Ctrl­D“.

# exit

Once you type exit it will record and upload your actions. When finished upload, it will generate a link at the end of each recording which you can share.

showterm recording finished.
Uploading...
http://showterm.io/9d34dc53ab91185448ef8

Here is a showterm recording that shows it’s usage:

I will use two showterm recording windows so as to demonstrate how to use it. This is the main showterm recording window inside which I will start another showterm window so as to demonstrate how to use it. In other words, I will use showterm itself to demonstrate how to use showterm! Isn’t that cool?

I start the first showterm recording window and then start another recording window inside the first window by typing command “showterm“.

1. #slow : To make it go slower. It actually plays the recording at real time speed.
2. #fast : To make it go faster.It actually plays the recording at double the original speed.
3. #stop : To stop it.

For example, you can slow the showterm recording by appending #slow to this link as shown below.

http://showterm.io/d1311caa9df1aa7cdb828#slow

Embedding with iframes

If you want to embed showterms in your website, you can embed it using the iframe tag. For example, to embed link “http://showterm.io/d1311caa9df1aa7cdb828“, you can add the following iframe code to your website.

<iframe src=”http://showterm.io/d1311caa9df1aa7cdb828” width=”640” height=”480”></iframe>

Conclusion

There’s a whole range of applications for it! Whether you are teaching a class full of students or want to teach someone about how to install an application or show them how to run a particular program on terminal, showterm is the way to go!

Also, it’s an open source application so, if you want to contribute to it, here’s the link to its source:

1. Showterm Homepage
2. Showterm Client on GitHub
3. Showterm Server on GitHub

Read Also: Record Programs and Games Using Simple Screen Recorder

Source

Zulip is an open source, powerful and easily extendable group or team chat application powered by Electron and React Native. It runs on every major operating system: Linux, Windows, MacOS; Android, iOS, and also has a web client.

It supports over 90 native integrations with external applications, under different categories including interactive bots, version control (Github, Codebase, Bitbucket etc.), communication, customer support, deployment, financial (Stripe), marketing, monitoring tools (Nagios and more), integration frameworks, productivity (Drop box, Google calender etc.) and so many others.

Zulip Features:

• Supports various types of notifications.
• Supports keyboard shortcuts.
• Supports a multilanguage spellchecker.
• Allows you to sign in to multiple teams.
• Offers a RESTful API and Python bindings for integration purposes.
• Supports a multitude of languages.
• Supports video calls and chat history.
• Also allows for full-text full-history search.
• Supports invite-only conversations.
• Supports private one-on-one or group conversations.
• Allows you to keep track of messages that are of interest to you.
• Shows who is currently online.
• Supports draft messages.
• Also supports typing notifications and much more.

How to Install Zulip Chat Application on Linux

On Debian/Ubuntu systems, you can install it from the Zulip desktop apt repository via the apt command.

First setup the zulip desktop app repository on your system and add its signing key, as follows, from a terminal.

$ sudo apt-key adv --keyserver pool.sks-keyservers.net --recv 69AD12704E71A4803DCA3A682424BE5AE9BD10D9
$ echo "deb https://dl.bintray.com/zulip/debian/ stable main" | sudo tee -a /etc/apt/sources.list.d/zulip.list

Then update your apt package sources cache and install the zulip client as shown.

$ sudo apt update
$ sudo apt install zulip

Once the installation is complete, search for zulip from your system menu and launch it, or run the zulip command from a terminal.

$ zulip

On other Linux distributions, you can install it via an AppImage. Go to the download page or use the wget command below to grab the appimage.

$ wget -c https://github.com/zulip/zulip-electron/releases/download/v1.9.0/Zulip-1.9.0-x86_64.AppImage

After downloading it, make the file executable and run it.

$ chmod a+x Zulip-x.x.x-x86_64.AppImage 
$ ./Zulip-x.x.x-x86_64.AppImage 

Note: If you use it this way, the app will not update automatically, you will need to repeat the above instructions to upgrade to newer versions.

How to Use Zulip Chat Application

When you launch zulip for the first time, you will land in the interface shown in the following screenshot, where you can add an organization. Click on Create a new organization, you will be redirected to the zulip website where you can create a new organization.

Add your email address and click on Create organization.

Next, a link to complete your signup will be sent to your email. After opening the link, register by providing your full name, password, organization name, organization URL (address you’ll use to log in to your organization) and accept terms of service. Then click on Sign Up.

You can continue to use the web client or back on the desktop app, use your organization URL to log in to your organization.

Then log into zulip with your email address and password as shown in the following screenshot.

Next, you can invite more users in your organization, and customize zulip to fit your organization’s needs, under settings.

Zulip Homepage: https://zulipchat.com/

Zulip is a cross-platform, powerful and highly extensible group chat application. Try it out and share your experience with us via the comment form below.

Source

Today, SMS (Short Message Service) has become more popular, it widely used all over the world in huge amounts for various business processes such as SMS Marketing, apart from the conventional communication platform. An SMS gateway allows a computer system to send or receive SMS to or from a telecommunications network, thus to or from mobile phones of clients.

There are a number of industry focused open source SMS gateway software solutions you can use to run your bulk SMS services. If you are searching for one, then this article is meant for you, you can check out the list below.

1. Jasmin – SMS Gateway

Jasmin is a free, open-source, very powerful, easily customizable, and high-performance SMS Gateway solution, built for full in-memory execution. It is intended for environments with traffic-clogged systems to meet specific business message exchange needs.

LibreOffice is an open source and much powerful personal productivity office suit for Linux, Windows & Mac, that provides feature rich functions for word document, data processing, spreadsheets, presentation, drawing, Calc, Math and much more. LibreOffice has large number of satisfied users across the globe with almost 120million downloads as of now. It supports more than 110 languages and runs on all major operating systems.

The Document Foundation team proudly announced the first major release of LibreOffice 6.0.4 on May 09, 2018, is now available for all major platforms including Linux, Windows and Mac OS.

This new update features a large number of exciting new features, performance and improvements and is targeted to all kinds of users, but especially appealing for enterprise, early adopters and power users.

There are many other changes and features included in the newest LibreOffice 6.0.4 – for a complete list of new features, see the release announcement page.

LibreOffice 6.0.4 Requirements

1. Kernel 2.6.18 or higher version
2. glibc2 version 2.5 or higher version
3. gtk version 2.10.4 or higher version
4. Minimum 256MB and recommended 512MB RAM
5. 1.55GB available Hard disk space
6. Desktop (Gnome or KDE)

Install LibreOffice 6.0.4 on Linux

The installation instructions provided here are for LibreOffice 6.0.4 using language US English on a 64-Bitsystem. For 32-Bit systems, there will be minor differences in directory names, but the installation process is same and hope the installation instructions provide here are not so difficult.

Step 1: Downloading LibreOffice 6.0.4

Select the package for download based on your system bit (i.e. for a 32-bit or 64-bit) using Wget command.

For RHEL/CentOS/Fedora

# cd /tmp

---------------------------- On 32-bit Systems ---------------------------- 
# wget http://download.documentfoundation.org/libreoffice/stable/6.0.4/rpm/x86/LibreOffice_6.0.4_Linux_x86_rpm.tar.gz


---------------------------- On 64-bit Systems ---------------------------- 
# wget http://download.documentfoundation.org/libreoffice/stable/6.0.4/rpm/x86_64/LibreOffice_6.0.4_Linux_x86-64_rpm.tar.gz

[root@TecMint ~]# wget http://download.documentfoundation.org/libreoffice/stable/6.0.4/rpm/x86_64/LibreOffice_6.0.4_Linux_x86-64_rpm.tar.gz
--2018-05-09 01:11:08--  http://download.documentfoundation.org/libreoffice/stable/6.0.4/rpm/x86_64/LibreOffice_6.0.4_Linux_x86-64_rpm.tar.gz
Resolving download.documentfoundation.org (download.documentfoundation.org)... 89.238.68.185, 2a00:1828:a012:185::1
Connecting to download.documentfoundation.org (download.documentfoundation.org)|89.238.68.185|:80... connected.
HTTP request sent, awaiting response... 302 Found
Location: https://ftp.gwdg.de/pub/tdf/libreoffice/stable/6.0.4/rpm/x86_64/LibreOffice_6.0.4_Linux_x86-64_rpm.tar.gz [following]
--2018-05-09 01:11:09--  https://ftp.gwdg.de/pub/tdf/libreoffice/stable/6.0.4/rpm/x86_64/LibreOffice_6.0.4_Linux_x86-64_rpm.tar.gz
Resolving ftp.gwdg.de (ftp.gwdg.de)... 134.76.12.6, 2001:638:60f:110::1:2
Connecting to ftp.gwdg.de (ftp.gwdg.de)|134.76.12.6|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 213537364 (204M) [application/octet-stream]
Saving to: ‘LibreOffice_6.0.4_Linux_x86-64_rpm.tar.gz’

100%[=================================================================================================================================>] 21,35,37,364  310KB/s   in 15m 35s

2018-02-01 01:26:46 (223 KB/s) - ‘LibreOffice_6.0.4_Linux_x86-64_rpm.tar.gz’ saved [213537364/213537364]

For Debian/Ubuntu/LinuxMint

---------------------------- On 32-bit Systems ---------------------------- 
$ wget http://download.documentfoundation.org/libreoffice/stable/6.0.4/deb/x86/LibreOffice_6.0.4_Linux_x86_deb.tar.gz

---------------------------- On 64-bit Systems ---------------------------- 
$ wget http://download.documentfoundation.org/libreoffice/stable/6.0.4/deb/x86_64/LibreOffice_6.0.4_Linux_x86-64_deb.tar.gz

tecmint  ~  wget http://download.documentfoundation.org/libreoffice/stable/6.0.4/deb/x86_64/LibreOffice_6.0.4_Linux_x86-64_deb.tar.gz
--2018-05-09 11:57:23--  http://download.documentfoundation.org/libreoffice/stable/6.0.4/deb/x86_64/LibreOffice_6.0.4_Linux_x86-64_deb.tar.gz
Resolving download.documentfoundation.org (download.documentfoundation.org)... 89.238.68.185
Connecting to download.documentfoundation.org (download.documentfoundation.org)|89.238.68.185|:80... connected.
HTTP request sent, awaiting response... 302 Found
Location: https://ftp.gwdg.de/pub/tdf/libreoffice/stable/6.0.4/deb/x86_64/LibreOffice_6.0.4_Linux_x86-64_deb.tar.gz [following]
--2018-05-09 11:57:23--  https://ftp.gwdg.de/pub/tdf/libreoffice/stable/6.0.4/deb/x86_64/LibreOffice_6.0.4_Linux_x86-64_deb.tar.gz
Resolving ftp.gwdg.de (ftp.gwdg.de)... 134.76.12.6
Connecting to ftp.gwdg.de (ftp.gwdg.de)|134.76.12.6|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 213964181 (204M) [application/octet-stream]
Saving to: ‘LibreOffice_6.0.4_Linux_x86-64_deb.tar.gz’

LibreOffice_6.0.0_Linux_x86-64_deb.tar.gz  100%[========================================================================================>] 204.05M   319KB/s    in 15m 17s 

2018-02-01 12:12:41 (228 KB/s) - ‘LibreOffice_6.0.4_Linux_x86-64_deb.tar.gz’ saved [213964181/213964181]

Step 2: Removing Old LibreOffice or OpenOffice Versions

If any previously installed LibreOffice or OpenOffice versions you have, remove it using following command.

# yum remove openoffice* libreoffice*			[on RedHat based Systems]

$ sudo apt-get remove openoffice* libreoffice*		[On Debian based Systems]

Step 3: Extracting LibreOffice 6.0.4 Package

After downloading the LibreOffice 6.0.4 package, use tar command to extract it under /tmp directory or in a directory of your choice.

On RHEL/CentOS/Fedora

# tar -xvf LibreOffice_6.0.4_Linux_x86_rpm.tar.gz		[On 32-Bit Systems]	
# tar -xvf LibreOffice_6.0.4_Linux_x86-64_rpm.tar.gz	        [On 64-Bit Systems]	

On Debian/Ubuntu/Linux Mint

$ tar -xvf LibreOffice_6.0.4_Linux_x86_deb.tar.gz		[On 32-Bit Systems]	
$ tar -xvf LibreOffice_6.0.4_Linux_x86-64_deb.tar.gz		[On 64-Bit Systems]	

Step 4: Installing LibreOffice 6.0.4 Package

After extracting the package, you will get a directory and under this there will be a sub-directory called RPMS. Now, run the following command to install it.

On RHEL/CentOS/Fedora

## For 32 Bit OS ##
# cd /tmp/LibreOffice_6.0.4.2_Linux_x86_rpm/RPMS/
# yum localinstall *.rpm
OR
# dnf install *.rpm    [On Fedora 23+ versions]

## For 64 Bit OS ##
# cd /tmp/LibreOffice_6.0.4.2_Linux_x86-64_rpm/RPMS/
# yum localinstall *.rpm
OR
# dnf install *.rpm    [On Fedora 23+ versions]

[root@localhost RPMS]# yum localinstall *.rpm
Dependencies Resolved

============================================================================================================================================================================
 Package                                                  Arch          Version            Repository                                                                  Size
============================================================================================================================================================================
Installing:
 libobasis6.0-base                                        x86_64        6.0.4.2-2          /libobasis6.0-base-6.0.4.2-2.x86_64                                        7.6 M
 libobasis6.0-calc                                        x86_64        6.0.4.2-2          /libobasis6.0-calc-6.0.4.2-2.x86_64                                         29 M
 libobasis6.0-core                                        x86_64        6.0.4.2-2          /libobasis6.0-core-6.0.4.2-2.x86_64                                        267 M
 libobasis6.0-draw                                        x86_64        6.0.4.2-2          /libobasis6.0-draw-6.0.4.2-2.x86_64                                         48 k
 libobasis6.0-en-US                                       x86_64        6.0.4.2-2          /libobasis6.0-en-US-6.0.4.2-2.x86_64                                       164 k
 libobasis6.0-extension-beanshell-script-provider         x86_64        6.0.4.2-2          /libobasis6.0-extension-beanshell-script-provider-6.0.4.2-2.x86_64         398 k
 libobasis6.0-extension-javascript-script-provider        x86_64        6.0.4.2-2          /libobasis6.0-extension-javascript-script-provider-6.0.4.2-2.x86_64        626 k
 libobasis6.0-extension-mediawiki-publisher               x86_64        6.0.4.2-2          /libobasis6.0-extension-mediawiki-publisher-6.0.4.2-2.x86_64               4.3 M
 libobasis6.0-extension-nlpsolver                         x86_64        6.0.4.2-2          /libobasis6.0-extension-nlpsolver-6.0.4.2-2.x86_64                         2.1 M
 libobasis6.0-extension-pdf-import                        x86_64        6.0.4.2-2          /libobasis6.0-extension-pdf-import-6.0.4.2-2.x86_64                        2.2 M
 libobasis6.0-extension-report-builder                    x86_64        6.0.4.2-2          /libobasis6.0-extension-report-builder-6.0.4.2-2.x86_64                    6.0 M
 libobasis6.0-firebird                                    x86_64        6.0.4.2-2          /libobasis6.0-firebird-6.0.4.2-2.x86_64                                     11 M
 libobasis6.0-gnome-integration                           x86_64        6.0.4.2-2          /libobasis6.0-gnome-integration-6.0.4.2-2.x86_64                           1.2 M
 libobasis6.0-graphicfilter                               x86_64        6.0.4.2-2          /libobasis6.0-graphicfilter-6.0.4.2-2.x86_64                               4.2 M
 libobasis6.0-images                                      x86_64        6.0.4.2-2          /libobasis6.0-images-6.0.4.2-2.x86_64                                       18 M
 libobasis6.0-impress                                     x86_64        6.0.4.2-2          /libobasis6.0-impress-6.0.4.2-2.x86_64                                     2.2 M
 libobasis6.0-kde-integration                             x86_64        6.0.4.2-2          /libobasis6.0-kde-integration-6.0.4.2-2.x86_64                             238 k
 libobasis6.0-librelogo                                   x86_64        6.0.4.2-2          /libobasis6.0-librelogo-6.0.4.2-2.x86_64                                   741 k
 libobasis6.0-math                                        x86_64        6.0.4.2-2          /libobasis6.0-math-6.0.4.2-2.x86_64                                        1.6 M
 libobasis6.0-ogltrans                                    x86_64        6.0.4.2-2          /libobasis6.0-ogltrans-6.0.4.2-2.x86_64                                    298 k
 libobasis6.0-onlineupdate                                x86_64        6.0.4.2-2          /libobasis6.0-onlineupdate-6.0.4.2-2.x86_64                                433 k
 libobasis6.0-ooofonts                                    x86_64        6.0.4.2-2          /libobasis6.0-ooofonts-6.0.4.2-2.x86_64                                     67 M
 libobasis6.0-ooolinguistic                               x86_64        6.0.4.2-2          /libobasis6.0-ooolinguistic-6.0.4.2-2.x86_64                               1.4 k
 libobasis6.0-postgresql-sdbc                             x86_64        6.0.4.2-2          /libobasis6.0-postgresql-sdbc-6.0.4.2-2.x86_64                             3.5 M
 libobasis6.0-python-script-provider                      x86_64        6.0.4.2-2          /libobasis6.0-python-script-provider-6.0.4.2-2.x86_64                       41 k
 libobasis6.0-pyuno                                       x86_64        6.0.4.2-2          /libobasis6.0-pyuno-6.0.4.2-2.x86_64                                        22 M
 libobasis6.0-writer                                      x86_64        6.0.4.2-2          /libobasis6.0-writer-6.0.4.2-2.x86_64                                       16 M
 libobasis6.0-xsltfilter                                  x86_64        6.0.4.2-2          /libobasis6.0-xsltfilter-6.0.4.2-2.x86_64                                  4.3 M
 libreoffice6.0                                           x86_64        6.0.4.2-2          /libreoffice6.0-6.0.4.2-2.x86_64                                           4.5 M
 libreoffice6.0-base                                      x86_64        6.0.4.2-2          /libreoffice6.0-base-6.0.4.2-2.x86_64                                       63  
 libreoffice6.0-calc                                      x86_64        6.0.4.2-2          /libreoffice6.0-calc-6.0.4.2-2.x86_64                                       63  
 libreoffice6.0-dict-en                                   x86_64        6.0.4.2-2          /libreoffice6.0-dict-en-6.0.4.2-2.x86_64                                    24 M
 libreoffice6.0-dict-es                                   x86_64        6.0.4.2-2          /libreoffice6.0-dict-es-6.0.4.2-2.x86_64                                   4.1 M
 libreoffice6.0-dict-fr                                   x86_64        6.0.4.2-2          /libreoffice6.0-dict-fr-6.0.4.2-2.x86_64                                   6.4 M
 libreoffice6.0-draw                                      x86_64        6.0.4.2-2          /libreoffice6.0-draw-6.0.4.2-2.x86_64                                       63  
 libreoffice6.0-en-US                                     x86_64        6.0.4.2-2          /libreoffice6.0-en-US-6.0.4.2-2.x86_64                                      16 k
 libreoffice6.0-freedesktop-menus                         noarch        6.0.4.2-2            /libreoffice6.0-freedesktop-menus-6.0.4.2-2.noarch                            30 M
 libreoffice6.0-impress                                   x86_64        6.0.4.2-2          /libreoffice6.0-impress-6.0.4.2-2.x86_64                                    66  
 libreoffice6.0-math                                      x86_64        6.0.4.2-2          /libreoffice6.0-math-6.0.4.2-2.x86_64                                       63  
 libreoffice6.0-ure                                       x86_64        6.0.4.2-2          /libreoffice6.0-ure-6.0.4.2-2.x86_64                                        38 M
 libreoffice6.0-writer                                    x86_64        6.0.4.2-2          /libreoffice6.0-writer-6.0.4.2-2.x86_64                                     65  

Transaction Summary
============================================================================================================================================================================
Install  41 Packages

Total size: 579 M
Installed size: 579 M
Is this ok [y/d/N]: y

On Debian/Ubuntu/Linux Mint

## For 32 Bit OS ##
$ cd /tmp/LibreOffice_6.0.4.2_Linux_x86_deb/DEBS/
$ sudo dpkg -i *.deb

## For 64 Bit OS ##
$ cd /tmp/LibreOffice_6.0.4.2_Linux_x86-64_deb/DEBS/
$ sudo dpkg -i *.deb

tecmint@TecMint /tmp/LibreOffice_6.0.4.2_Linux_x86-64_deb/DEBS $ sudo dpkg -i *.deb
Selecting previously unselected package libobasis6.0-base.
(Reading database ... 263169 files and directories currently installed.)
Preparing to unpack libobasis6.0-base_6.0.4.2-2_amd64.deb ...
Unpacking libobasis6.0-base (6.0.4.2-2) ...
Selecting previously unselected package libobasis6.0-calc.
Preparing to unpack libobasis6.0-calc_6.0.4.2-2_amd64.deb ...
Unpacking libobasis6.0-calc (6.0.4.2-2) ...
Selecting previously unselected package libobasis6.0-core.
Preparing to unpack libobasis6.0-core_6.0.4.2-2_amd64.deb ...
Unpacking libobasis6.0-core (6.0.4.2-2) ...
...

Step 5: Starting LibreOffice 6.0.4

Once the installation process completes you will have LibreOffice icons in your desktop under Applications –> Office menu or start the application by executing the following command on the terminal.

# libreoffice6.0

Step 6: Screenshot of LibreOffice 6.0.4

Please see the attached screenshot of LibreOffice 6.0.4 application under my CentOS 7.0.

Step 7: Installing a Language Pack

If you would like to install LibreOffice in your preferred language, you should select your language pack for installation. The installation instructions can be fount at Language Pack section.

Source

Gerbera is a feature-rich and powerful UPnP (Universal Plug and Play) media server with a pleasant and intuitive web user interface, which allows users to stream digital media (videos, images, audio etc..) through a home network and consume it on different types of UPnP compatible devices from mobile phone to tablets and many more.

Gerbera Features:

• Allows you to browse and playback media via UpnP.
• Supports metadata extraction from mp3, ogg, flac, jpeg, etc. files.
• Highly flexible configuration, allowing you to control the behavior of various features of the server.
• Supports user defined server layout based on extracted metadata.
• Support for ContentDirectoryService container updates.
• Offers exif thumbnail support.
• Supports automatic directory rescans (timed, inotify).
• Offers a nice Web UI with a tree view of the database and the file system, allowing to add/remove/edit/browse media.
• Support for external URLs (create links to internet content and serve them via UPnP to your renderer).
• Supports flexible media format transcoding via plugins / scripts and many more including a number of experimental features.

How to Install Gerbera – UPnP Media Server in Linux

On Ubuntu distribution, there is a PPA created and maintained by Stephen Czetty, from which you can install Gerbera using following commands.

$ sudo add-apt-repository ppa:stephenczetty/gerbera
$ sudo apt update
$ sudo apt install gerbera 

On Debian distribution, Gerbera is available in the testing and unstable repositories, which you can enable by adding the lines below in your /etc/apt/sources.list file.

# Testing repository - main, contrib and non-free branches
deb http://http.us.debian.org/debian testing main non-free contrib
deb-src http://http.us.debian.org/debian testing main non-free contrib

# Testing security updates repository
deb http://security.debian.org/ testing/updates main contrib non-free
deb-src http://security.debian.org/ testing/updates main contrib non-free

# Unstable repo main, contrib and non-free branches, no security updates here
deb http://http.us.debian.org/debian unstable main non-free contrib
deb-src http://http.us.debian.org/debian unstable main non-free contrib

Then update your system package sources cache and install gerbera with the following commands.

# apt update
# apt install gerbera

For other Linux distributions like Gentoo, Arch Linux, openSUSE, CentOS, etc. follow Gerbera installation guide.

Once you have installed gerbera, start, enable and view the service status using the following commands.

$ sudo systemctl start gerbera.service 
$ sudo systemctl enable gerbera.service
$ sudo systemctl status gerbera.service

Note: If gerbera fails to start on your system, you need to do one of the following.

Check if the log file (/var/log/gerbera) has been created, otherwise create it as shown.

$ sudo touch /var/log/gerbera
$ sudo chown -Rv root:gerbera /var/log/gerbera
$ sudo chmod -Rv 0660 /var/log/gerbera

Secondly, define a network interface that your are currently using as the value of MT_INTERFACE environment variable, the default is “eth0” but if you are using wireless, then set this to something like “wlp1s0”. In Debian/Ubuntu, you can set these settings in /etc/default/gerbera file.

Getting Started with Gerbera Media Server Web UI

Gerbera service listens on port 49152, which you can use to access the web UI via a web browser as shown.

http://domain.com:49152
OR
http://ip-address:49152

If you get the error shown in the above screenshot, you need to enable the web UI from the gerbera configuration file.

$ sudo vim /etc/gerbera/config.xml

Change the value enabled=”no” to enabled=”yes” as shown in the following screenshot.

After making above changes, close the file and restart the gerbera service.

$ sudo systemctl restart gerbera.service

Now go back to your browser and try to open the UI once more in a new tab, this time around it should load. You will see two tabs:

• Database – shows the files that can be accessed by publicly.

• Filesystem – this is where you can browse files from your system and select them for streaming. To add a file, simply click on the plus (+) sign.

After adding files for streaming from the filesystem, the database interface should look like this.

Stream Media Files Using Gerbera on Your Home Network

At this point you can start streaming media files over your network from the gerbera server. To test it, we will use a mobile phone as a client. Start by installing a compatible upnp application (like BubbleUpnp) on your phone.

Once installed BubbleUpnp app, open it and on the menu, go to Library and click on Local and Cloud to view available servers, and the gerbera server we created should show in there. Click on it to access added directories and files in them.

Finally click on a file that you would like to stream.

For more information visit, Gerbera Github Repository: https://github.com/gerbera/gerbera.

Gerbera is a feature-rich and powerful Upnp media server, used to stream your digital media through your home network with a nice web user interface. Share your thoughts about it or ask a question via the feedback form.

Source

Lychee is a free, open source, elegant and easy-to-use photo-management system, which comes with all the necessary features you need for securely managing and sharing photos on your server. It allows you to easily manage (upload, move, rename, describe, delete or search) your photos in seconds from a simple web application.

Lychee Features

• A stunning, beautiful interface to manage all your photos in one place, right from your browser.
• One click photo and album sharing with password protection.
• View all your images in full-screen mode with forward and backward navigation using your keyboard or let others browse your photos by making them public.
• Supports importing of photos from various sources: localhost, Dropbox, remote server, or using a link.

To install Lychee, everything you need is a running web-server such as Apache or Nginx with PHP 5.5 or later and a MySQL-Database.

For the purpose of this article, I will be installing Lychee photo-management system with Nginx, PHP-FPM 7.0and MariaDB on a CentOS 7 VPS with domain name lychee.example.com.

Step 1: Install Nginx, PHP and MariaDB

1. First start by installing Nginx, PHP with needed extensions and MariaDB database to setup a hosting environment to run Lychee.

On Cent/RHEL 7

# yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
# yum install http://rpms.remirepo.net/enterprise/remi-release-7.rpm
# yum install yum-utils
# yum-config-manager --enable remi-php70   [Install PHP 7.0]
# yum install nginx php php-fpm php-mysqli php-exif php-mbstring php-json php-zip php-gd php-imagick mariadb-server mariadb-client

On Ubuntu 16.04 and 18.04

$ sudo apt install nginx php php-fpm php-mysqli php-exif php-mbstring php-json php-zip php-gd php-imagick mariadb-server mariadb-client

2. Once you have installed the necessary packages, start nginx, php-fpm and mariadb services, enable them at boot time and check if these services are up and running.

------------ CentOS/RHEL ------------
# systemctl start nginx php-fpm mariadb
# systemctl status nginx php-fpm mariadb
# systemctl enable nginx php-fpm mariadb

------------ Debian/Ubuntu ------------
$ sudo systemctl start nginx php7.0-fpm mysql
$ sudo systemctl status nginx php7.0-fpm mysql
$ sudo systemctl enable nginx php7.0-fpm mysql

3. Next, if you have a firewall enabled on your system, you need to open the port 80 and 443 in the firewall to allow client requests to the Nginx web server on the HTTP and HTTPS respectively, as shown.

------------ Debian/Ubuntu ------------
$ sudo  ufw  allow 80/tcp
$ sudo  ufw  allow 443/tcp
$ sudo  ufw  reload

------------ CentOS/RHEL ------------
# firewall-cmd --zone=public --permanent --add-port=80/tcp
# firewall-cmd --zone=public --permanent --add-port=443/tcp
# firewall-cmd --reload

4. In order to run Lychee effectively, it is recommended to increase the values of the following properties in php.ini file.

# vim /etc/php/php.ini			#CentOS/RHEL
$ sudo vim /etc/php/7.0/fpm/php.ini     #Ubuntu/Debian 

Search for these PHP parameters and change their values to:

max_execution_time = 200
post_max_size = 100M
upload_max_size = 100M
upload_max_filesize = 20M
memory_limit = 256M

5. Now configure PHP-FPM to set the user and group, listen socket www.conf file as explained.

# vim /etc/php-fpm.d/www.conf		        #CentOS/RHEL
$ sudo vim /etc/php/7.0/fpm/pool.d/www.conf	#Ubuntu/Debian

Look for the directives below to set the Unix user/group of processes (change www-data to nginx on CentOS).

user = www-data
group = www-data

Also change the listen directive on which to accept FastCGI requests to a Unix socket.

listen = /run/php/php7.0-fpm.sock

And set the appropriate ownership permissions for the Unix socket using the directive (change www-data to nginx on CentOS/RHEL).

listen.owner = www-data
listen.group = www-data

Save the file and restart the nginx and php-fpm services.

# systemctl restart nginx php-fpm              #CentOS/RHEL
$ sudo systemctl restart nginx php7.0-fpm      #Ubuntu/Debian

Step 2: Secure MariaDB Installation

6. In this step, you should secure the MariaDB database installation (which is unsecured by default if installed on a fresh system), by running the security script which comes with the binary package.

Run the following command as root, to launch the the script.

$ sudo mysql_secure_installation

You will be prompted to set a root password, remove anonymous users, disable root login remotely and remove test database. After creating a root password, and answer yes/y to the rest of questions.

Enter current password for root (enter for none):
Set root password? [Y/n] y Remove anonymous users? [Y/n] y Disallow root login remotely? [Y/n] y Remove test database and access to it? [Y/n] y Reload privilege tables now? [Y/n] y

Step 3: Install Lychee Photo Management System

7. To install Lychee, first you need to create a database for it with appropriate permissions using following commands.

$ sudo mysql -u root -p
MariaDB [(none)]> CREATE DATABASE lychee; 
MariaDB [(none)]> CREATE USER 'lycheeadmin'@'localhost' IDENTIFIED BY '=@!#@%$Lost';
MariaDB [(none)]> GRANT ALL PRIVILEGES ON  lychee.* TO 'lycheeadmin'@'localhost';
MariaDB [(none)]> FLUSH PRIVILEGES;
MariaDB [(none)]> exit

$ cd /var/www/html/
$ sudo git clone --recurse-submodules https://github.com/LycheeOrg/Lychee.git

------------ CentOS/RHEL ------------
# chown admin:nginx -R /var/www/html/Lychee
# chmod 775 -R /var/www/html/Lychee

------------ Debian/Ubuntu ------------
$ sudo chown admin:www-data -R /var/www/html/Lychee
$ sudo chmod 775  -R /var/www/html/Lychee

# cd Lychee/
# php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
# php -r "if (hash_file('sha384', 'composer-setup.php') === '93b54496392c062774670ac18b134c3b3a95e5a5e5c8f1a9f115f203b75bf9a129d5daa8ba6a13e2cc8a1da0806388a8') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
# php composer-setup.php
# php -r "unlink('composer-setup.php');"
# php composer.phar update

# vim /etc/nginx/conf.d/lychee.conf

server {
	listen      80;
	server_name	 lychee.example.com;
	root         	/var/www/html/Lychee/;
	index       	index.html;

	charset utf-8;
	gzip on;
	gzip_types text/css application/javascript text/javascript application/x-javascript 	image/svg+xml text/plain text/xsd text/xsl text/xml image/x-icon;
	location / {
		try_files $uri $uri/ /index.php?$query_string;
	}
	location ~ \.php {
		include fastcgi.conf;
		fastcgi_split_path_info ^(.+\.php)(/.+)$;
		fastcgi_pass unix:/run/php/php7.0-fpm.sock;
	}
	location ~ /\.ht {
		deny all;
	}
}

# systemctl restart nginx php-fpm              #CentOS/RHEL
$ sudo systemctl restart nginx php7.0-fpm      #Ubuntu/Debian

Fasd (pronounced as “fast“) is command-line productivity booster, a self-contained POSIX shell script which enables quick and more efficient access to files and directories.

It is inspired by tools such as autojump, and the name fasd was created from the default suggested aliases:

• f(files)
• a(files/directories)
• s(show/search/select)
• d(directories)

It has been tested on the following shells: bash, zsh, mksh, pdksh, dash, busybox ash, FreeBSD 9 /bin/sh and OpenBSD /bin/sh. It keeps track of files and directories you have accessed, so that you can quickly reference them in the command line.

In this article, we will show how to install and use fasd with a few examples in Linux.

How Does fasd Work?

Fasd simply ranks files and directories by “frecency” (word was first invented by Mozilla and used in Firefox, find out more from here) a combination of the words “frequency” and “recency“.

If you use primarily the shell via the terminal to navigate and launch applications, fasd can enable you do it more efficiently. It helps you to open files regardless of which directory you are in.

With simple key strings, fasd can find a “frecent” file or directory and open it with command you specify.

How to Install and Use Fasd in Linux Systems

Fasd can be installed using PPA on Ubuntu and its derivatives.

$ sudo add-apt-repository ppa:aacebedo/fasd
$ sudo apt-get update
$ sudo apt-get install fasd

On other Linux distributions, you can install it from source as shown.

$ git clone https://github.com/clvv/fasd.git
$ cd fasd/
$ sudo make install

Once you have installed Fasd, add the following line to your ~/.bashrc to enable it:

eval "$(fasd --init auto)"

Then source the file like this.

$ source ~/.bashrc

Fasd ships with the following useful default aliases:

alias a='fasd -a'        # any
alias s='fasd -si'       # show / search / select
alias d='fasd -d'        # directory
alias f='fasd -f'        # file
alias sd='fasd -sid'     # interactive directory selection
alias sf='fasd -sif'     # interactive file selection
alias z='fasd_cd -d'     # cd, same functionality as j in autojump
alias zz='fasd_cd -d -i' # cd with interactive selection

Let’s look at a few usage examples; the following example will list any “frecent” files and directories:

$ a

To quickly search a file or directory you accessed previously, use the s alias:

$ s

To view all files you previously worked with that have the letters “vim”, you can use the f alias as follows:

$ f vim

To quickly and interactively cd into a previously accessed directory using the zz alias. Simply select the directory number from the first field (1-24 in the screenshot below):

$ zz

You can add your own aliases in ~/.bashrc to fully utilize the power of fasd as in the examples below:

alias v='f -e vim'   # quick opening files with vim
alias m='f -e vlc'   # quick opening files with vlc player

Then run the following command to source the file:

$ source  ~/.bashrc

To open a file quickly named test.sh in vim, you would type:

$ v test.sh

We will cover one more example where you can use Fasd aliases with other commands:

$ f test
$ cp  `f test` ~/Desktop
$ ls -l ~/Desktop/test.sh

For bash users, call _fasd_bash_hook_cmd_complete to make completion work. For example:

_fasd_bash_hook_cmd_complete  v  m  j  o

For more information, type:

$ man fasd

For additional customizations and usage examples, check out Fasd Github repository: https://github.com/clvv/fasd/

That’s all! In this article, we showed you how to install and use fasd in Linux. Do share with us info about similar tools you have come across out there, together with any other thoughts via the feedback section below.

Source

GNU Make is a development utility which determines the parts of a particular code base that are to be recompiled and can issue commands to perform those operations on the code base. This particular make utility can be used with any programming language provided that their compilation can be done from the shell by issuing commands.

In order to use GNU Make, we need to have some set of rules which defines the relationship among different files in our program and commands for updating each file. These are written onto a special file called ‘makefile‘. The ‘make‘ command uses the ‘makefile‘ data base and the last modification times of the files to decide which all files are to recompiled again.

Contents of a Makefile

Generally ‘makefiles‘ contain 5 kinds of things namely: implicit rules, explicit rules, variable definitions, directives, and comments.

1. An explicit rule specifies how to make/remake one or more files (called targets, will be explained later) and when to do the same.
2. An implicit rule specifies how to make/remake one or more files based on their names. It describes how a target file name is related to one file with a name similar to the target.
3. A variable definition is a line that specifies a string value for a variable to be substituted later.
4. A directive is an instruction for make to do something special while reading the makefile.
5. A ‘#’ symbol is used represent the start of a comment inside makefiles. A line starting with ‘#’ is simply ignored.

Structure of Makefiles

The information that tells make how to recompile a system comes from reading a data base called the makefile. A simple makefile will consists of rules of the following syntax:

target ... : prerequisites ... 
	recipe 
... 
...

A target is defined to be the output file generated by the program. It can be also phony targets, which will be explained below. Examples of target files include executables, object files or phony targets like clean, install, uninstall etc.

A prerequisite is a file that is used as an input to create the target files.

A recipe is the action that make performs for creating the target file based on the prerequisites. It is necessary to put tab character before each recipe inside the makefiles unless we specify the ‘.RECIPEPREFIX‘ variable to define some other character as prefix to recipe.

A sample Makefile

final: main.o end.o inter.o start.o
	gcc -o final main.o end.o inter.o start.o
main.o: main.c global.h
	gcc -c main.c
end.o: end.c local.h global.h
	gcc -c end.c
inter.o: inter.c global.h
	gcc -c inter.c
start.o: start.c global.h
	gcc -c start.c
clean:
	rm -f main.o end.o inter.o start.o

In the above example we used 4 C source files and two header files for creating the executable final. Here each ‘.o’ file is both a target and a prerequisite inside the makefile. Now take a look at the last target name clean. It is just a action rather than a target file.

Since we normally don’t need this during compilation, it is not written as a prerequisite in any other rules. Targets that do not refer to files but are just actions are called phony targets. They will not have any prerequisites as other target files.

How GNU Make process a Makefile

By default make starts off with the first target in the ‘makefile‘ and is called as ‘default goal’. Considering our example, we have final as our first target. Since its prerequisites include other object files those are to be updated before creating final. Each of these prerequisites are processed according to their own rules.

Recompilation occurs if there are modifications made to source files or header files or if the object file does not exists at all. After recompiling the necessary object files, make decides whether to relink final or not. This must be done if the file final does not exist, or if any of the object files are newer than it.

Thus if we change the file inter.c, then on running make it will recompile the source file to update the object file inter.o and then link final.

Using variables inside Makefiles

In our example, we had to list all the object files twice in the rule for final as shown below.

final: main.o end.o inter.o start.o
	gcc -o final main.o end.o inter.o start.o

In order to avoid such duplications, we can introduce variables to store the list of object files that are being used inside the makefile. By using the variable OBJ we can rewrite the sample makefile to a similar one shown below.

OBJ = main.o end.o inter.o start.o
final: $(OBJ)
	gcc -o final $(OBJ)
main.o: main.c global.h
	gcc -c main.c
end.o: end.c local.h global.h
	gcc -c end.c
inter.o: inter.c global.h
	gcc -c inter.c
start.o: start.c global.h
	gcc -c start.c
clean:
	rm -f $(OBJ)

Rules for cleaning the source directory

As we saw in the example makefile, we can define rules to clean up the source directory by removing the unwanted object files after the compilation. Suppose we happen to have a target file called clean. How can make differentiate the above two situations? Here comes the concept of phony targets.

A phony target is one that is not really the name of a file, rather it is just a name for a recipe to be executed whenever an explicit request is made from the makefile. One main reason to use phony target is to avoid a conflict with a file of the same name. Other reason is to improve performance.

To explain this thing, I will reveal one unexpected twist. The recipe for clean will not be executed by default on running make. Instead it is necessary to invoke the same by issuing the command make clean.

.PHONY: clean
clean:
	rm -f $(OBJ)

Now try to create makefiles for your own code base. Feel free to comment here with your doubts.

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