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kingyou
kingyou

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What `apt upgrade` Actually Does

apt upgrade does not update the system version. It only upgrades minor versions of already installed packages and will not change the Debian release (e.g., from bookworm to trixie).

apt upgrade: Only updates existing package versions
- bash 5.2.15 → bash 5.2.21 (bug fixes, security patches)
- btop 1.3.2 → btop 1.3.3 (new features)
- Will NOT: bookworm → Debian 13
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Safety Limits:

  • No new packages installed
  • No old packages removed
  • No dependency changes

System Version Upgrade Commands

Command Purpose Risk
apt upgrade Minor updates (daily recommended) Low
apt full-upgrade / apt-get dist-upgrade Major updates (may add/remove packages) Medium
do-release-upgrade Release upgrade (bookworm→trixie) High

Practical Usage

# Daily maintenance (recommended)
sudo apt update && sudo apt upgrade -y

# When new dependencies needed (use carefully)
sudo apt full-upgrade

# Change system version (rarely used)
sudo do-release-upgrade  # Debian/Ubuntu only
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Docker Production Best Practice:

# Only security patches, no compatibility breaks
RUN apt-get update && apt-get upgrade -y \
 && apt-get autoremove -y \
 && rm -rf /var/lib/apt/lists/*
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One Sentence Summary: apt upgrade = bug fixes/patches, NOT system version change.

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