Because Alpine Linux is designed to run from RAM, package management involves two phases:
- Installing / Upgrading / Deleting packages on a running system.
- Restoring a system to a previously configured state (e.g. after reboot), including all previously installed packages and locally modified configuration files. (RAM-Based Installs Only)
apk is the tool used to install, upgrade, or delete software on a running system.
lbu is the tool used to capture the data necessary to restore a system to a previously configured state.
The apk tool supports the following operations:
|Add new packages or upgrade packages to the running system
|Delete packages from the running system
|Attempt to repair or upgrade an installed package
|Update the index of available packages
|Prints information about installed or available packages
|Search for packages or descriptions with wildcard patterns
|Upgrade the currently installed packages
|Maintenance operations for locally cached package repository
|Compare version differences between installed and available packages
|create a repository index from a list of packages
|download (but not install) packages
|List changes to the file system from pristine package install state
|Verify a package signature
|Create a graphviz graph description for a given package
|Display the repository that updates a given package, plus repositories that also offer the package
|Display statistics, including number of packages installed and available, number of directories and files, etc.
|Display checksums for files contained in a given package
Packages and Repositories
Software packages for Alpine Linux are digitally signed tar.gz archives containing programs, configuration files, and dependency metadata. They have the extension
.apk, and are often called "a-packs".
The packages are stored in one or more repositories. A repository is simply a directory with a collection of *.apk files. The directory must include a special index file, named APKINDEX.tar.gz to be considered a repository.
The apk utility can install packages from multiple repositories. The list of repositories to check is stored in /etc/apk/repositories, one repository per line. If you booted from a USB stick (/media/sda1) or CD-ROM (/media/cdrom), your repository file probably looks something like this:
In addition to local repositories, the apk utility uses busybox wget to fetch packages using http:, https:, ftp: or rsync: protocols. The following is a valid repository file:
You can specify additional "tagged" repositories in /etc/apk/repositories:
After which you can "pin" dependencies to these tags using:
apk will by default only use the untagged repositories, but adding a package with a @tag:
1. will prefer the repository with that tag for the named package, even if a later version of the package is available in another repository
2. allows pulling in dependencies for the tagged package from the tagged repository (though it prefers to use untagged repositories to satisfy dependencies if possible)
Commandline repository options
By default, the apk utility will use the system repositories for all operations. This behavior can be overridden by the following options:
|Override the system repositories by specifying a repositories file.
|Specify a supplemental repository that will be used in addition to the system repositories. This option can be provided multiple times.
Update the Package list
Remote repositories change as packages are added and upgraded. To get the latest list of available packages, use the update command. The command downloads the APKINDEX.tar.gz from each repository and stores it in the local cache, typically /var/cache/apk/, /var/lib/apk/ or /etc/apk/cache/.
--update-cache, or for short
-U switch to another apk command, as in
apk --update-cache upgrade or
apk -U add ..., the command has the same effect as first running
apk update before the other apk command.
Add a Package
Use add to install packages from a repository. Any necessary dependencies are also installed. If you have multiple repositories, the add command installs the newest package.
If you only have the main repository enabled in your configuration, apk will not include packages from the other repositories. To install a package from the edge/testing repository without changing your repository configuration file, use the command below. This will tell apk to use that particular repository.
Add a local Package
To install a locally available apk package, for example if this device has no internet access but you can upload apk packages directly to it, use the --allow-untrusted flag:
Note that multiple packages can be given. When installing a local package, all dependencies should also be specified. For example:
Remove a Package
Use del to remove a package (and dependencies that are no longer needed.)
Upgrade a Running System
Packages in general
To get the latest security upgrades and bugfixes available for the installed packages of a running system, first update the list of available packages and then upgrade the installed packages:
Or, combining the same into one single command:
Here is an example, showing the procedure on a system that has several additional repositories pinned:
# apk update fetch https://dl-3.alpinelinux.org/alpine/v3.6/main/x86_64/APKINDEX.tar.gz fetch https://dl-3.alpinelinux.org/alpine/v3.6/community/x86_64/APKINDEX.tar.gz fetch https://dl-3.alpinelinux.org/alpine/edge/main/x86_64/APKINDEX.tar.gz fetch https://dl-3.alpinelinux.org/alpine/edge/community/x86_64/APKINDEX.tar.gz fetch https://dl-3.alpinelinux.org/alpine/edge/testing/x86_64/APKINDEX.tar.gz v3.6.2-191-gf98d79930f [https://dl-3.alpinelinux.org/alpine/v3.6/main] v3.6.2-190-ga5d68c47df [https://dl-3.alpinelinux.org/alpine/v3.6/community] v3.6.0-4618-g0bf77c9821 [https://dl-3.alpinelinux.org/alpine/edge/main] v3.6.0-4605-g85ed51dd83 [https://dl-3.alpinelinux.org/alpine/edge/community] v3.6.0-4624-g11f1b9c8ab [https://dl-3.alpinelinux.org/alpine/edge/testing] OK: 20118 distinct packages available # apk upgrade (1/2) Upgrading extra-cmake-modules@testing (5.38.0-r0 -> 5.39.0-r0) (2/2) Upgrading extra-cmake-modules-doc@testing (5.38.0-r0 -> 5.39.0-r0) Executing mdocml-apropos-1.14.1-r0.trigger OK: 2635 MiB in 803 packages
To upgrade only specific packages, use the upgrade command and specify them:
To enable unattended, automatic upgrades of packages, see thepackage.
To upgrade to a newer release, refer to the corresponding release notes and Upgrading_Alpine.
Upgrading "diskless" and "data" disk mode installs
If booting a "diskless" system from a read-only device, or iso image on writable media, it's not possible to update the boot files (kernel, modules, firmware, ...) that reside on that device.
It becomes possible to update the boot files, though, if using a boot device that is writable and has been prepared with
However, even then, the kernel, with its modules and firmware files, can still not be updated directly through regular packages updates. Instead, there is the
update-kernel script that can generate initfs images and install them together with upgraded kernels.
Upgrading can be done as follows.
This package is required for the generation of the initial filesystem used during boot.
- Additional initfs features that are missing in the default configuration, like the btrfs filesystem support (at the time of writing, to allow loading .apkovl configs and package cache during boot), may be enabled in
- Available initfs features may be listed with
Finally update the kernel and its boot environment.
update-kernelrun needs at least 8 GB free ram memory to avoid a broken modloop-image.
update-kernel --helpfor options to manually add additional module or firmware packages.
Search for Packages
The search command searches the repository Index files for installable packages.
The return format is Package-Version. Omit Version for apk add Package
- To list all packages available, along with their descriptions:
- To list all packages are part of the ACF system:
- To list all packages that list NTP as part of their description, use the -d or --description option:
Information on Packages
The info command provides information on the contents of packages, their dependencies, and which files belong to a package.
For a given package, each element can be chosen (for example, -w to show just the webpage information), or all information displayed with the -a command.
zlib-1.2.5-r1 description: A compression/decompression Library zlib-1.2.5-r1 webpage: https://zlib.net zlib-1.2.5-r1 installed size: 94208 zlib-1.2.5-r1 depends on: libc0.9.32 zlib-1.2.5-r1 is required by: libcrypto1.0-1.0.0-r0 apk-tools-2.0.2-r4 openssh-client-5.4_p1-r2 openssh-5.4_p1-r2 libssl1.0-1.0.0-r0 freeswitch-1.0.6-r6 atop-1.25-r0 zlib-1.2.5-r1 contains: lib/libz.so.1.2.5 lib/libz.so.1 lib/libz.so zlib-1.2.5-r1 triggers:
As shown in the example you can determine
- The description of the package (-d or --description)
- The webpage where the application is hosted (-w or --webpage)
- The size the package will require once installed (in bytes) (-s or --size)
- What packages are required to use this one (depends) (-R or --depends)
- What packages require this one to be installed (required by) (-r or --rdepends)
- The contents of the package, that is, which files it installs (-L or --contents)
- Any triggers this package sets. (-t or --triggers) Listed here are directories that are watched; if a change happens to the directory, then the trigger script is run at the end of the apk add/delete. For example, doing a depmod once after installing all packages that add kernel modules.
Listing installed packages
To list all installed packages, use:
To list all installed packages in alphabetical order, with a description of each, do:
The apk tool does not have a subcommand to list manually-installed packages that do not have reverse dependencies. To get this information on a traditional system that is not using lbu, try this script. Note that this approach will also list core packages like alpine-base that should not be removed.
#!/bin/sh apk info | grep -ve '-doc$' | sort | while read pkg do rdep=`apk info -qr "$pkg"` [ -z "$rdep" ] && echo $pkg done
To display the repository a package was installed from and will be updated from, plus any tagged or enabled repositories where it is also offered, if any, for this architecture - its policy:
$ apk policy vlc vlc policy: 2.2.6-r1: lib/apk/db/installed https://dl-3.alpinelinux.org/alpine/v3.7/community 3.0.0_rc2-r1: @edgecommunity https://dl-3.alpinelinux.org/alpine/edge/community
Additional apk Commands
To have the packages available during boot, apk can keep a cache of installed packages on a local disk.
Added packages can then be automatically (re-)installed from local media into RAM when booting, without requiring, and even before there is a network connection.
The cache can be stored on any writable media, or at the same location as the .apkovl file from the local backup utility
Enabling Local Cache with current releases
Execute the script
and it will assist in enabling a local cache.
The script creates a symlink named /etc/apk/cache that points to the cache directory.
Removing older packages
When newer packages are added to the cache over time, the older versions of the packages default to remain in the cache directory.
The older versions of packages can be removed with the clean command.
Or to see what is deleted include the verbose switch:
Download missing packages
If you accidentally delete packages from the cache directory, you can make sure they are there with the download command,
Delete and download in one step
You can combine the two steps into one with the sync command - this cleans out old packages and downloads missing packages.
Automatically Cleaning Cache on Reboot
To automatically attempt to validate your cache on reboot, you can add the above command to a /etc/local.d/*.stop file:
Special Caching Configurations
Enabling Local Cache on HDD installs
Note that HDD 'sys' installs don't need an apk cache to maintain their state, it allows to serve packages over the network, though, e.g. to get installed by other local machines.
Manually create a cache dir and then symlink it to /etc/apk/cache:
Local Cache on tmpfs volumes
In some circumstances it might be useful to have the cache reside on tmpfs, for example if you only wish for it to last as long as the system is up.
NOTE: apk is coded to ignore tmpfs caches, and this is correct behaviour in most instances. Using tmpfs as a package cache can consume large amounts of system memory if you install a lot of packages, possibly resulting in a crashed system. You can limit this by restricting the size of your cache to a small number (128M in the example below).
To do it, you need to create an image inside which your cache can live. We do this by creating an image file, formatting it with ext2, and mounting it at /etc/apk/cache.
As usual, if you want to download currently installed packages into the cache, use apk cache sync.
Manually Enabling Local Cache (required for releases prior to v2.3)
- Create a cache directory on the storage device where you keep the lbu backups (typically, /dev/sda1.)
- Create a symlink to this directory from /etc/apk/cache.
- Run an lbu commit to save the change (/etc/apk/cache is in /etc and is automatically backed up.)
Now whenever you run an apk command that pulls a new package from a remote repository, the package is stored on your local media. On startup, Alpine Linux will check the local cache for new packages, and will install them if available.
Advanced APK Usage
Holding a specific package back
In certain cases, you may want to upgrade a system, but keep a specific package at a back level. It is possible to add "sticky" or versioned dependencies. For instance, to hold the asterisk package to the 1.6.2 level or lower:
after which a
will upgrade the entire system, keeping the asterisk package at the 1.6.0 or lower level
To later upgrade to the current version,
will ensure that 1.6.1 is the minimum version used.
You can also use "fuzzy" version matching to pin the version to a major/minor release. For example:
will match any version of asterisk that starts with 1.6 (such as 18.104.22.168-r0 or 22.214.171.124-r9) <ref>Alpine source commit message</ref>
If you desire deterministic, repeatable package installation (such as with containerized environments) via package pinning, it is important to understand your package repo's version retention rules. For example, most Alpine package repos contain an "edge" branch, which may drop package versions that are not deemed fit to make it into a stable branch. This means that pinning to a version on the edge branch may stop working after the package version is revoked from the repo. Always pin to a package version that is intended for your current Alpine Linux version.
If you'd like to trigger an action or run a certain script on every commit made by apk, there's a built-in method for that. On every commit apk looks for executables located in the "/etc/apk/commit_hooks.d/" directory, and executes them both before and after the commit. To provide some way to selectively run hooks either before or after a change is commited by apk, the scripts are called with "pre-commit" or "post-commit" as argument 1. This is an example of a hook to do different things before and after commit:
Commit hooks are $PATH-aware, so for the sake of security it's recommended to specify absolute paths to executables.
Table of comparison with other Linux/Unix-like OSes for packages
|apt, aptitude, dpkg
"apk-tools is old"
apk update, apk upgrade or apk add may report the following:
WARNING: This apk-tools is OLD! Some packages might not function properly
This may happen if you are running Alpine Linux stable version with a certain edge/main, edge/community or testing package(s) also installed. One resolution is to consider upgrading tagged in your repositories, then try:. If edge is already
ERROR: UNTRUSTED signature
This happens when the release version changes. You need to update the local apk keys.
If you have already updated your repositories, allow them to update without the trusted key:
Then install the keys upgrade:
Now updates and upgrades should proceed normally.
Alternative, the updated alpine-keys package may be obtained, verified, installed directly, as covered earlier, prior to a repository update.
- 10 Alpine Linux apk Command Examples Vivek Gite 2019