The alternatives system (provided by the chkconfig package in RHEL/Fedora) manages symbolic links that point to different implementations of similar commands. For example, both Sendmail and Postfix can provide the mta group to implement the sendmail command.

# Display information about a specific alternatives group
alternatives --display mta

While we can inspect individual groups with --display, the system doesn't provide a straightforward way to list all available groups. This becomes problematic when:

• You need to configure an alternative but forgot the group name
• You want to audit all configurable alternatives on a system
• You're troubleshooting command conflicts

Here are three reliable methods to discover all configured alternatives:

Method 1: Using the alternatives Directory

The alternatives system stores its configuration in /var/lib/alternatives/. Each file represents a group:

ls -1 /var/lib/alternatives/

Method 2: Using update-alternatives

On Debian-based systems, you can use:

update-alternatives --get-selections

Method 3: Comprehensive Script Approach

For cross-distribution compatibility, use this shell script:

#!/bin/bash
if command -v update-alternatives >/dev/null; then
    update-alternatives --get-selections | awk '{print $1}'
elif [ -d /var/lib/alternatives ]; then
    ls -1 /var/lib/alternatives/
else
    echo "Could not determine alternatives location" >&2
    exit 1
fi

Let's examine some common alternatives groups:

# View editor alternatives
alternatives --display editor

# Check available Java implementations
alternatives --display java

# See installed Python versions
alternatives --display python

For system administrators managing multiple servers, consider this audit script:

#!/bin/bash
echo "=== ALTERNATIVES AUDIT REPORT ==="
echo "Generated: $(date)"
echo "Hostname: $(hostname)"
echo ""

echo "=== Configured Groups ==="
if [ -d /var/lib/alternatives ]; then
    for group in $(ls -1 /var/lib/alternatives/); do
        echo -e "\n=== Group: $group ==="
        alternatives --display "$group" | head -n 5
    done
fi

• Some alternatives may be managed by package managers (like dnf or apt)
• Changes to alternatives persist after package upgrades
• Always test changes in a non-production environment first

---

The alternatives system in RHEL/Fedora (managed by the chkconfig package) provides a way to maintain symbolic links for commands with multiple implementations. For example, both Sendmail and Postfix can provide the sendmail command through the mta alternatives group.

While you can inspect specific alternatives groups using:

alternatives --display mta

The fundamental problem is discovering all available groups in the first place. Unlike many Linux commands, alternatives doesn't have a built-in listing option.

The alternatives system maintains its configuration under /var/lib/alternatives/. Each file in this directory represents a configurable alternatives group.

Here's how to list all available alternatives groups:

ls -1 /var/lib/alternatives/

Common alternatives groups you might find include:

• mta - Mail Transport Agent
• java - Java runtime
• editor - System default editor
• xdg-open - Default application handler

For more programmatic access, you can use this bash one-liner:

for alt in $(ls -1 /var/lib/alternatives/); do 
    echo "=== $alt ==="
    alternatives --display $alt | head -5
done

On Debian-based systems, you can use:

update-alternatives --get-selections

Understanding available alternatives is crucial for:

• System administration and configuration
• Troubleshooting command path issues
• Maintaining consistency across multiple systems
• Automating server provisioning