Maintaining an up-to-date Gentoo Linux system requires careful execution of several steps to ensure system stability while keeping packages current. Below I'll share the most reliable upgrade procedure I've developed through years of Gentoo administration.

Here's the fundamental upgrade workflow that has proven most effective:

# Synchronize portage tree
emerge --sync

# Perform a deep system upgrade
emerge -uDav --tree world

# Clean obsolete dependencies
emerge -av --depclean

# Rebuild broken reverse dependencies
revdep-rebuild -v -- --ask

# Handle configuration files
dispatch-conf

# Check for security advisories
glsa-check -t all
glsa-check -f all

When executing emerge -uDav --tree world, pay attention to:

• USE flag changes that might affect dependencies
• Blocked packages that require manual intervention
• Compiler flags consistency across the system

Case 1: When encountering masked packages:

# Check package masking
emerge -pv package_name

# Temporarily unmask if appropriate
echo "=category/package-version" >> /etc/portage/package.accept_keywords

Case 2: When dealing with configuration file changes:

# Alternative to dispatch-conf for batch processing
etc-update --automode -3

For complex systems, consider these additional steps:

# Preserve builds to avoid recompilation
emerge @preserved-rebuild

# Check for obsolete libraries
emerge -av --depclean --with-bdeps=y

# Verify package integrity
emaint checks

For regular maintenance, create a cron job:

0 3 * * * root /usr/bin/emerge --sync && \
/usr/bin/emerge -uDav --tree world && \
/usr/bin/emerge -av --depclean && \
/usr/bin/revdep-rebuild

Common solutions to frequent problems:

# Resolve file collisions
emerge --ask --verbose --oneshot app-portage/portage-utils
qcheck --verify

# Fix broken dependencies
emerge -av --oneshot --nodeps conflicting_package

---

The standard Gentoo upgrade procedure you've been using is fundamentally sound, but let's examine each step in detail and explore potential optimizations:

# Basic sync and upgrade commands
emerge --sync
emerge -uDav --tree world
emerge -av --depclean
revdep-rebuild -v -- --ask
dispatch-conf
glsa-check -t all
glsa-check -f all

Consider using emaint sync --auto instead of emerge --sync as it provides better feedback and handles multiple repos:

# More robust sync command
emaint sync --auto
# Alternative for git-based repos
emerge --sync --quiet

The -uDav flags are excellent, but consider adding --keep-going for complex systems:

# More resilient world update
emerge -uDav --keep-going --tree --with-bdeps=y @world

Add --with-bdeps=y to ensure build dependencies are properly considered:

# Thorough depclean
emerge -av --depclean --with-bdeps=y

For modern systems, revdep-rebuild has been largely superseded by emerge @preserved-rebuild:

# Newer method for reverse dependencies
emerge @preserved-rebuild

dispatch-conf remains solid, but consider etc-update for batch processing:

# Alternative config management
etc-update --automode -5

Your GLSA checks are thorough. For automation, you might combine them:

# Combined security check
glsa-check -t all && glsa-check -f all

Consider adding these post-upgrade checks:

# Check for obsolete packages
emerge --depclean --pretend
# Verify system integrity
emerge -e @system
# Clean distfiles
eclean-dist --deep

Here's a complete upgrade script with error handling:

#!/bin/bash

set -e

echo "Starting Gentoo system upgrade..."
emaint sync --auto || emerge --sync

echo "Upgrading world packages..."
emerge -uDav --keep-going --tree --with-bdeps=y @world || {
    echo "World upgrade failed - attempting to resolve..."
    emerge --resume --skipfirst
}

echo "Cleaning dependencies..."
emerge -av --depclean --with-bdeps=y

echo "Rebuilding preserved packages..."
emerge @preserved-rebuild

echo "Checking for security updates..."
glsa-check -t all && glsa-check -f all

echo "System upgrade completed successfully!"

If you encounter problems:

# Check for blockers
emerge -pv @world
# Rebuild potentially broken packages
emerge -1v $(qfile -C /usr/lib64/libstdc++.so.6)
# Check for file collisions
emerge -pv --verbose-conflicts @world