mere is a package manager for Mere Linux that combines ideas from Nix — content-addressed storage, immutable packages, atomic upgrades and rollbacks — with the simplicity of traditional Unix conventions.

This page walks through the main concepts and shows what they look like in practice.

The Store

Every package lives in /mere/store under a path derived from the hash of its contents. Because identity comes from content, store objects are immutable: changing anything produces a new hash and a new path.

$ ls /mere/store | tail -5
d14e3cf6…-busybox-1.37.0
fa885783…-execline-2.9.4.0
fcd990e9…-libcxx-21.1.8
fdc5a786…-musl-1.2.5
883ea055…-patch-2.8

Multiple versions of the same package coexist safely — they’re just different directories. Nothing is ever overwritten.

Profiles

A profile is a directory of symlinks that points into the store. It defines which packages are visible without copying or moving anything.

$ ls -l /mere/profiles/system/gen-12/usr/bin/
awk   -> /mere/store/d14e3cf6…-busybox-1.37.0/usr/bin/awk
env   -> /mere/store/d14e3cf6…-busybox-1.37.0/usr/bin/env
patch -> /mere/store/883ea055…-patch-2.8/usr/bin/patch

Each time you install or remove a package, a new generation is created. The active generation is a single symlink:

$ ls -l /mere/profiles/system/
current -> gen-16
gen-11/
gen-12/
gen-13/
…
gen-16/

Rolling back is just pointing current at an older generation. The operation is atomic — the system is never in a half-updated state.

System Activation

On a Mere Linux system, the root filesystem directories are themselves symlinks into the active profile:

$ ls -l /
bin  -> /mere/profiles/system/current/bin
lib  -> /mere/profiles/system/current/lib
sbin -> /mere/profiles/system/current/sbin
…

$ ls -l /usr
bin     -> /mere/profiles/system/current/usr/bin
lib     -> /mere/profiles/system/current/usr/lib
include -> /mere/profiles/system/current/usr/include
share   -> /mere/profiles/system/current/usr/share
…

Activating a new system generation updates which profile these paths resolve to. The package artifacts in the store are never touched.

Recipes

Packages are defined in KDL recipe files. A recipe declares metadata, sources, and build/install phases:

recipe {
    name "make"
    version "4.4.1"
    release 3
    description "A tool to control the generation of executables"
    url "http://www.gnu.org/software/make/"
    licenses "GPL3"
    archs "aarch64" "x86_64"
    depends "busybox" \
            "linux-headers" \
            "llvm" \
            "make" \
            "mimalloc-dev" \
            "musl-dev"
}

source "http://mirror.rit.edu/gnu/make/make-${recipe.version}.tar.gz" {
    blake3 "a7d8aee97b7e9a525ef561afa84eea0d929f246e3aafa420231c0602151cf9eb"
}

build {
    script r#"
        LDFLAGS="$LDFLAGS -static -Wl,-static" \
            ./configure --prefix=/usr \
            --disable-load
        make V=1
    "#
}

install {
    script r#"
        make DESTDIR="${DESTDIR}" install
    "#
}

package "make" {
    files "usr/bin/" \
          "usr/share/man/man1/"
}

Builds run inside Linux user namespaces for isolation. Each phase is cached independently — if build succeeds but install fails, the next run restarts from install without rebuilding.

Dependencies are discovered automatically from ELF metadata and shebangs rather than declared manually at the runtime level.

Configuration Management

/etc belongs to the user. Packages never overwrite files there.

When a package includes configuration files, the build system automatically relocates them from etc/ to etc-defaults/. On system activation, mere compares defaults against what’s in /etc:

  • Missing — the default is copied into place
  • Identical — nothing to do
  • Different — left untouched, drift is recorded

The mere etc command lets you inspect and resolve drift:

$ mere etc status
Active system /etc status: 1 differing, 0 missing, 12 unchanged
  differing: /etc/myapp/config.conf <- myapp

$ mere etc diff /etc/myapp/config.conf

$ mere etc apply /etc/myapp/config.conf

If two packages try to provide the same /etc path, activation fails with a clear error rather than silently picking a winner.

User Packages

The store directory is mode 1777, so unprivileged users can install packages for their own builds and personal profiles without root access.

$ ls -l /mere/store | grep jeremy
drwxr-xr-x  jeremy jeremy  fcd990e9…-libcxx-21.1.8

Before a user-installed package can be activated in the system profile, mere performs a full verification and migrates ownership. System activation is the trust boundary — the store is open, but the system profile is not.

Shell Environments

mere shell lets you enter an isolated environment based on any profile. It uses Linux user namespaces — no root required, no containers.

$ mere shell -p myprofile

Inside the shell, you see a filesystem assembled from the selected profile: /bin, /lib, /usr etc. are read-only bind mounts from the profile’s symlink tree into the store. /home and /var are passed through from the host. /mere is mounted read-write so you can install packages from inside the session.

/etc gets an overlayfs layer — you see the host’s /etc but any changes are isolated to the session and discarded on exit. If overlayfs isn’t available, --no-etc-overlay falls back to a read-only bind mount.

You can also run a single command without entering an interactive shell:

$ mere shell -p build -- make -j4

The profile can also be set via the MERE_SHELL_PROFILE environment variable, which is useful for scripting or setting a default in your shell rc file.

Because each shell session is scoped to a profile, you can have different environments for different tasks — a minimal profile for runtime, a full toolchain profile for development — without them interfering with each other or with the host system.

Signed Manifests

Every package carries a signed manifest at .mere/manifest.v1 that records its name, version, architecture, content hash, and build timestamp. The content hash is computed over the package payload excluding the manifest itself, so the signature binds the declared identity to the exact artifact in the store.