Debian Knowledge Patch

Claude's baseline knowledge covers Debian 12 (Bookworm). This skill provides changes in Debian 13 "Trixie" (August 2025).

Breaking Changes Quick Reference

Change	Impact	Details
/tmp is tmpfs	Large temp files may exhaust RAM	system-changes
last/lastb/lastlog removed	Use wtmpdb, lastlog2, lslogins	system-changes
OpenSSH DSA keys removed	No workaround; use Ed25519	system-changes
~/.pam_environment ignored	Set vars in shell init files	system-changes
systemd-cryptsetup split	Install before reboot if encrypted	system-changes
dm-crypt defaults changed	Record cipher/hash in crypttab	system-changes
RabbitMQ HA queues removed	Switch to quorum queues; no direct upgrade	server-changes
MariaDB 10.11 -> 11.8	Clean shutdown required before upgrade	server-changes
i386 legacy-only	No kernel/installer; do NOT upgrade	architecture-changes

New Features

systemd run0

Privilege escalation tool that replaces sudo. Checks for "sudo" group membership, asks for user's password (not root's).

apt modernize-sources

apt modernize-sources  # convert old SourcesList format to deb822

curl HTTP/3 and wcurl

curl --http3 https://example.com # HTTP/3 support
curl --http3-only https://example.com
wcurl https://example.com/file.tar.gz # simple wget alternative

System Changes

/tmp as tmpfs

Default: up to 50% of RAM. Customize:

systemctl edit tmp.mount
# Add: Options=mode=1777,nosuid,nodev,size=2G

Revert: systemctl mask tmp.mount && reboot

Login Tracking Replacements

Old Command	Replacement	Packages Needed
last	wtmpdb	wtmpdb, libpam-wtmpdb
lastlog	lastlog2	lastlog2, libpam-lastlog2
lastb	lslogins --failed	util-linux (included)

Also new: lslogins for account last-used info. exch and waitpid added to util-linux-extra. mesg and write removed.

OpenSSH Changes

• DSA keys completely removed (OpenSSH 9.8p1). Use openssh-client-ssh1 for legacy devices.
• ~/.pam_environment no longer read. Move variables to ~/.bash_profile or ~/.bashrc.

Encrypted Filesystem Changes

• Install systemd-cryptsetup before rebooting (split from systemd).
• Plain-mode dm-crypt new defaults: cipher=aes-xts-plain64, hash=sha256. For old devices, add cipher=aes-cbc-essiv:sha256,size=256,hash=ripemd160 to /etc/crypttab.
• LUKS devices unaffected (settings stored on device).

/usr Merge Complete

usrmerge and usr-is-merged are now removable dummy packages.

See references/system-changes.md for full details.

Server Changes

RabbitMQ

HA queues removed. Must switch to quorum queues. No direct upgrade from bookworm -- wipe /var/lib/rabbitmq/mnesia and restart.

MariaDB 10.11 -> 11.8

Ensure clean shutdown before upgrade. Crash recovery across major versions not supported:

systemctl stop mariadb  # ensure clean shutdown before upgrading

See references/server-changes.md for full details.

Architecture Changes

• i386: Legacy-only (multiarch/chroot on amd64). No kernel, no installer. Do NOT upgrade i386 systems.
• riscv64: First official Debian support for 64-bit RISC-V.
• armel: Last supported release. Migrate to armhf or arm64.
• mipsel/mips64el: Removed entirely.
• /boot: Needs at least 768 MB with ~300 MB free for upgrade.

See references/architecture-changes.md for details.

Desktop

Plasma 6 (First in Debian)

• Plasma 6.3.6 (replaces 5.27.5)
• Qt 6.8.2 (from 6.4.2)
• KDE Frameworks 6.13
• Qt 5.15.15 and KF5 5.116 for compatibility (deprecated, removal in forky)
• GNOME 48

64-bit time_t Transition

All architectures except i386 use 64-bit time_t (Y2038-safe). On 32-bit arches (armel, armhf), library ABIs changed without soname changes. Third-party software needs recompilation.

Key Package Versions

Package	Bookworm (12)	Trixie (13)
Kernel	6.1	6.12
Python	3.11	3.13
GCC	12.2	14.2
OpenSSH	9.2p1	10.0p1
OpenSSL	3.0	3.5
systemd	252	257
PostgreSQL	15	17
MariaDB	10.11	11.8
PHP	8.2	8.4
Perl	5.36	5.40
Rustc	1.63	1.85
LLVM	14 default	19 default
Samba	4.17	4.22
GIMP	2.10	3.0
curl	7.88	8.14
LibreOffice	7.x	25
GNOME	43	48
Emacs	28.2	30.1

Reference Files

File	Contents
system-changes.md	tmpfs /tmp, login tracking, OpenSSH, encryption, systemd changes
server-changes.md	RabbitMQ, MariaDB, package version details
architecture-changes.md	i386, riscv64, armel, mips removal, /boot sizing