Install PHP 7.2 and extensions

As Linux Mint‘s popularity has skyrocketed over the past decade, with some estimates putting it as the 4th most popular desktop Linux distribution globally, its rich ecosystem of software packages has grown exponentially. With over 30,000 packages available from the Linux Mint repositories alone, mastering software management is an essential skill for any Mint user.

In this comprehensive 2600+ word guide, I‘ll cover the various package managers available within Mint, best practices for maintaining stability, resolving common issues, and leveraging packaging in development workflows – drawing on my expertise as a full-stack developer.

Understanding Linux Mint‘s Package Management Ecosystem

At a high level, Linux Mint relies on the dpkg package manager and Ubuntu‘s Advanced Packaging Tool (APT) for working with .deb file packages. While dpkg offers low-level package manipulation, APT provides dependency resolution and higher-level management functions.

These tools interact with online software repositories to install, upgrade and remove packages. The main Linux Mint repos include reliable, vetted packages suitable for most users. 3rd party PPAs allow access to more niche packages, but can create stability issues if not carefully maintained.

Key Graphical Package Managers

For new Linux users, Linux Mint offers several graphical package managers that wrap much of the underlying APT and dpkg functionality in easy to use interfaces:

• Software Manager – The default package tool in Mint, it provides an app store style interface to browse and install packages from configured APT repositories. Easy to use, but lighter on advanced functionality compared to Synaptic.
• Synaptic – More full-featured compared to Software Manager, Synaptic enables lower level package control. You can force certain package versions, manage repositories, fix broken packages and locks. Useful for resolving complex issues.
• Muon – A lighter, faster alternative GUI for package management. Provides transaction history and notifications when new updates are available. Well suited for older hardware.

As a developer, I generally use the command line APT interface instead for scripting installs and deployments. But the graphical tools are great for casual users first dipping into package management.

APT: Powerful Command Line Package Management

While Mint‘s graphical managers provide convenience, nearly all their functionality maps to underlying APT commands for those who prefer the power and automation of the Linux command line:

Common APT Operations

• sudo apt update – Refresh package index from repositories
• sudo apt upgrade – Install available package upgrades
• sudo apt full-upgrade – Upgrade packages with auto-handling of dependencies
• sudo apt install [package] – Install new packages
• sudo apt remove [package] – Uninstall packages
• sudo apt autoremove – Remove unneeded package dependencies
• apt list --upgradable – List packages with updates
• apt search [query] – Search for packages

This just scratches the surface of available commands – the apt man page has over 80 options and 20 subcommands! From my developer perspective, having such a powerful toolset to script and automate Linux package management is invaluable.

APT Repositories

APT relies on configured software repositories to install and upgrade packages from. The main Linux Mint repos provide thousands of vetted, open source packages. Third party PPAs can supplement these but should be validated before use, as they can negatively impact stability.

Here is a quick overview of APT repository management:

• apt policy [package] – Check which repo a package originates from
• add-apt-repository [PPA] – Safely add 3rd party repositories
• apt-cache policy – Verify which repos are configured
• rm /etc/apt/sources.list.d/[repo].list – Remove unwanted PPAs

So in summary – leaning the ins and outs of APT is critical for both Mint users and developers needing greater control over Linux package management.

dpkg: Low Level Package Manipulation

Underlying all of Linux Mint‘s package management sits the dpkg utility. It allows direct installation, removal and querying of local .deb packages without any dependency resolution. Key use cases include:

• Install package directly from a .deb file, skipping repositories
• List contents of a .deb without actually installing it
• Enumerate all currently installed packages
• List files installed from a particular package
• Check and verify packages without changes

Some common dpkg operations:

• dpkg -i [package].deb – Install/reinstall .deb package
• dpkg -r [package] – Remove package
• dpkg -l [package] – List package details
• dpkg --contents [package].deb – List files inside a .deb without installing
• dpkg --get-selections – Print installed package details

While powerful, dpkg does have some key limitations to be aware of:

• No dependency resolution – if a .deb requires other packages, dpkg won‘t auto-install them
• No package downloads – .deb files must be acquired separately
• No upgrades – simply overwrites existing package files

No authentication – requires extra `sudo` privilege

Because of these constraints, dpkg is best used alongside higher level managers like APT rather than exclusively.

Best Practices for Stable Linux Mint Package Management

When working with such an extensive package ecosystem, following some core best practices will keep your system running smoothly:

Leverage Package Channels

Linux Mint packages are split into release channels indicating their stability and testing level:

• Stable – Fully tested packages good for production systems.
• Testing – Packages still under evaluation. Useful for trying new features safely.
• Unstable – Bleeding edge packages still in early development.

I‘d encourage only staying on the Stable channel unless you specifically want early previews of certain packages. Mixing Stable with Testing/Unstable significantly raises chances of hittting conflicts.

Avoid Dependency Version Mismatch

With numerous packages interacting, their dependencies can easily get out of sync causingBREAKING things. If one package upgrades before its dependent, it may no longer integrate correctly.

Sticking to the official Linux Mint repos mitigates most of these "dependency hell" scenarios. But 3rd party PPAs often lag behind on updates. One technique is to assign package version HOLDs:

sudo apt-mark hold [package]

This locks the package version down so connected software doesn‘t inadvertently break it.

Use Apt Preferences to Force Package Versions

If you do need specific package versions rather than the latest, you can also leverage /etc/apt/preferences.d/ to enforce selections globally.

For example, creating a 99-keep-old-php.pref file with:

Package: php* 
Pin: version 7.2*
Pin-Priority: 1001

Would make APT retain PHP 7.2.x even if newer versions exist in repositories.

Test Updates Before Committing

No better test than production? Not when it comes to critical infrastructure updates. I suggest using Mint‘s Update Manager to preview available updates before pulling the trigger:

Review the packages being upgraded and their changelogs first. For site reliability, possibly spin up a staging server as final check before updating production.

Troubleshooting Common Linux Mint Package Issues

Despite best efforts, package problems still occur. Here are quick resolutions for frequent scenarios:

Fixing Unmet Dependencies

If you attempt to install a package via APT and see "unmet dependencies" errors, try:

sudo apt --fix-broken install
sudo dpkg --configure -a

To force a reconfiguration check and install any missing dependencies.

Unlocking Held Packages

APT will sometimes hold needed packages from upgrading if it detects possible BREAKING issues. View and override with:

apt-mark showhold
sudo apt-mark unhold [package]  

Then re-attempt the upgrade.

Reinstalling Corrupted Packages

If a package becomes corrupted or partially installed, use:

sudo apt install --reinstall [package]

Or with dpkg:

 
sudo dpkg -P [package] ; sudo dpkg -i [package]

To fully purge and reinstall from scratch.

Clearing APT Cache to Free Space

The APT cache storing downloaded .deb packages can consume gigabytes over time. Clear it with:

sudo apt clean

For moderate space savings or:

  
sudo apt autoclean

To only remove outdated cache packages.

So in summary – proactively avoiding issues is preferable, but tools like dpkg and APT flags can resolve many emergent issues.

Leveraging Packaging in Development Workflows

Beyond installing software, Linux package management has many direct use cases for developers like myself:

• Deployment Automation – Script installs of language stacks, app servers and other dependencies
• Infrastructure as Code – Definition of server configs with repeatable idempotent package states
• Build Reproducibility – Packages give consistent, pinned dependency sets for compiling code
• Container Reduction – Install dependencies at deploy time rather than baking into images

For example, needing to migrate a legacy PHP application to a new Ubuntu server, I could script the stack setup with:

#!/bin/bash

sudo apt update
sudo apt install -y php7.2 php7.2-mysql php7.2-curl  

sudo a2dismod mpm_event && sudo a2enmod mpm_prefork cgi

sudo apt install -y nginx php7.2-fpm

This reusable package script allows reliable rebuilding of the environment anytime.

Or for container size reduction, rather than installing hundreds of megabytes of packages inside docker images, you can leverage small base images and install application dependencies only at initial deployment time.

So Linux package management has certainly earned its place as an invaluable Swiss Army Knife for developers and engineers.

Wrapping Up

In closing, Linux Mint provides a wealth of mature, robust package management solutions for desktop users and developers alike. From simple graphical tools like Software Manager to advanced command line package scripting with APT, it flexible covers the entire software lifecycle spectrum – install, upgrade, remove.

With over 30,000 packages across the official Linux Mint repositories, the ecosystem continues accelerating as this Debian-based distribution cements itself as a dominant force in the Linux universe. This guide just scratches the surface of available package management capabilities and best practices. I encourage all Mint users to continually deepen their knowledge in order to unlock the full potential of this world class open source platform.