STORAGECTL(1)

💾 STORAGECTL — the manual, but make it cute

okay bestie, sit down, hydrate, because we're about to talk about storagectl and its lil alias mount.storage — and yes, it's giving "enumerate and mount storage volumes provided by storage providers". that's the NAME section, that's literally what it does. 💅

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✨ SYNOPSIS ✨

storagectl [OPTIONS...] {COMMAND} [NAME...]

mount -t storage PROVIDER:VOLUME DIRECTORY

mount -t storage.FSTYPE PROVIDER:VOLUME DIRECTORY

no cap, that's the whole vibe. three ways in, all slay. 🌸

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🦋 DESCRIPTION 🦋

so like, storagectl is your girl for inspecting storage providers and the storage volumes they expose. what's a storage provider, you ask? it's a service implementing the io.systemd.StorageProvider Varlink[1] interface, registered as an AF_UNIX socket below the well-known socket directory /run/systemd/io.systemd.StorageProvider/ (in system mode) or $XDG_RUNTIME_DIR/systemd/io.systemd.StorageProvider/ (in user mode). yes, that's a mouthful, we love that for it.

the two storage providers shipped with systemd are systemd-storage-block@.service(8), which exposes the system's block devices, and systemd-storage-fs@.service(8), which exposes regular files and directories from a backing file system. two icons, both iconic. 👑

the tool also provides a mount(8) helper for the file system type "storage", which permits mounting storage volumes to arbitrary places. see "Use as a mount helper" below for details. we'll get there, don't skip ahead, it's rude (affectionate).

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🎀 COMMANDS 🎀

the following commands are understood. memorize them, they're your main character moments:

• volumes [GLOB] — list storage volumes provided by all storage providers running on the system (or, with --user, in the user runtime). the optional GLOB argument is a shell-style pattern (see fnmatch(3)) that filters the result by volume name. the output is a table containing the providing service, the volume name, its type ("blk", "reg" or "dir"), whether it is read-only, and — if known — its size and the number of bytes used.

this is the default command if none is specified. so if you're lazy (no judgement, same) you just get this one for free.

added in version 261.

• templates [GLOB] — list volume templates supported by the running storage providers. templates encapsulate a configuration to use when creating volumes on-the-fly, when they are acquired. template support is an optional feature for providers, and only applies to providers that allow creation of volumes on-the-fly. see the respective provider documentation for details, for example systemd-storage-fs@.service(8). the optional GLOB argument filters by template name. storage providers that do not implement template-based volume creation (such as the block-device provider) do not contribute to this output. they're just not invited to this party, and that's okay. 🙈

added in version 261.

• providers — list the storage providers known to the system. this is determined by scanning the well-known socket directory for AF_UNIX sockets that look like io.systemd.StorageProvider endpoints. for each provider it is also reported whether the socket can currently be connected to. it's a vibe check, basically. 🔥

added in version 261.

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💅 OPTIONS 💅

the following options are understood. pick your faves, there's no wrong answer (there's a couple wrong answers, but we'll get to those):

• --system — operate on system-wide storage providers. sockets are looked for in /run/systemd/io.systemd.StorageProvider/. this is the default.

added in version 261.

• --user — operate on per-user storage providers. sockets are looked for in $XDG_RUNTIME_DIR/systemd/io.systemd.StorageProvider/.

added in version 261.

• --json=MODE — shows output formatted as JSON. expects one of "short" (for the shortest possible output without any redundant whitespace or line breaks), "pretty" (for a pretty version of the same, with indentation and line breaks) or "off" (to turn off JSON output, the default).
• --no-pager — do not pipe output into a pager. sometimes you just want it ALL at once, we get it.
• --no-legend — do not print the legend, i.e. column headers and the footer with hints. goodbye scaffolding, hello raw data. ✨
• --no-ask-password — do not query the user for authentication for privileged operations.
• -h, --help — print a short help text and exit.
• --version — print a short version string and exit.

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🌈 USE AS A MOUNT HELPER 🌈

this is the part where things get spicy. the tool provides the /sbin/mount.storage alias, implementing the mount(8) "external helper" interface, allowing storage volumes to be mounted with the regular mount command. the volume to mount is encoded as the source of the mount, in the form "PROVIDER:VOLUME", where PROVIDER is the name of a storage provider (as listed by storagectl providers) and VOLUME is the volume name. two file system type spellings are recognized:

• "storage" — acquires a directory volume and bind-mounts its directory tree onto the target.

added in version 261.

• "storage.FSTYPE" — acquires a regular file or block device volume and mounts it as a file system of type FSTYPE (for example "storage.ext4", "storage.btrfs", ...).

added in version 261.

the standard -o mount options are forwarded to mount. in addition, the following "storage."-prefixed options are interpreted by mount.storage itself and stripped from the forwarded list — so they never make it to mount, they're handled in-house, girlboss behavior:

• storage.create=MODE — takes one of "any" (open if it exists, otherwise create — the default), "open" (fail if the volume does not yet exist) or "new" (fail if the volume already exists).

added in version 261.

• storage.template=NAME — the template to use when creating a new volume, if it is missing and the provider supports on-the-fly creation of volumes.

added in version 261.

• storage.create-size=BYTES — when creating a new volume on-the-fly, the size in bytes to allocate. accepts the usual "K"/"M"/"G"/"T" suffixes (base 1024). required when creating a regular file volume. not optional, bestie, it's a whole thing. 😭

added in version 261.

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🍓 EXAMPLES 🍓

Example 1. Enumerate available storage providers, volumes and templates

$ storagectl providers
$ storagectl volumes
$ storagectl volumes '*foo*'
$ storagectl templates

look at her go. four commands, zero stress. 🧚

Example 2. Mount a directory volume from the file system provider

# mount -t storage fs:myvol /mnt/myvol

if the volume "myvol" does not yet exist, it will be created using the default "subvolume" template. it literally manifested itself, we love a self-made queen. 💜

Example 3. Create and mount an ext4 file system from a regular file.

# mount -t storage.ext4 fs:scratch /mnt/scratch -o loop

Example 4. Mount a block device volume read-only

# mount -t storage.ext4 -o ro block:/dev/disk/by-id/usb-foo /mnt/foo

read-only, boundaries set, communication clear. obsessed. 🫶

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⭐ EXIT STATUS ⭐

on success, 0 is returned, a non-zero failure code otherwise. that's it, that's the status. classic. 💖

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🌸 ENVIRONMENT (aka your vibe dials) 🌸

okay bestie, these are the environment variables that storagectl and friends actually pay attention to. set them in your shell, in your service, wherever — they'll listen. 💖

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$SYSTEMD_LOG_LEVEL

This is the maximum log level for messages that get emitted. Anything with a higher log level (which means less important, yes it's backwards, iykyk) gets suppressed entirely. 🙈

It takes a comma-separated list of values. Each value is either one of these, listed in order of decreasing importance:

1. emerg
2. alert
3. crit
4. err
5. warning
6. notice
7. info
8. debug

…or an integer in the range 0...7. Peep syslog(3) if you want the full lore.

Each value can optionally be prefixed with one of console, syslog, kmsg or journal, followed by a colon, to set the max log level for that specific log target. Like, for example:

SYSTEMD_LOG_LEVEL=debug,console:info

That says: log at debug level, except when logging to the console, which should be info level. 💅

⚠️ Heads up: the global maximum log level takes priority over any per-target maximum log levels. So don't come for me when your per-target setting gets overruled.

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$SYSTEMD_LOG_COLOR

A boolean. If it's true, messages written to the tty get colored according to priority. 🌈

This is only useful when messages are written directly to the terminal, because journalctl(1) and other log-displaying tools will color messages based on the log level all on their own. They don't need your help bestie, they're booked and busy.

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$SYSTEMD_LOG_TIME

A boolean. If true, console log messages get prefixed with a timestamp. ⏰

Again, only useful when messages go directly to the terminal or a file, because journalctl(1) and other log-displaying tools attach timestamps based on the entry metadata themselves. periodt.

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$SYSTEMD_LOG_LOCATION

A boolean. If true, messages get prefixed with a filename and line number in the source code where the message originates. 📍

ngl, the log location is often attached as metadata to journal entries anyway. But putting it directly in the message text can still be convenient when you're debugging programs. So, your call.

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$SYSTEMD_LOG_TID

A boolean. If true, messages get prefixed with the current numerical thread ID (TID). 🧵

This information is attached as metadata to journal entries anyway. But again — including it directly in the message text can be convenient when debugging programs.

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$SYSTEMD_LOG_TARGET

Where your log messages actually go. Pick one:

• console — log to the attached tty
• console-prefixed — log to the attached tty, but with prefixes encoding the log level and "facility", see syslog(3)
• kmsg — log to the kernel circular log buffer
• journal — log to the journal
• journal-or-kmsg — log to the journal if it's available, and to kmsg otherwise
• auto — determine the appropriate log target automatically. This is the default. 👑
• null — disable log output entirely (silence, iconic)

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$SYSTEMD_LOG_RATELIMIT_KMSG

Whether to ratelimit kmsg or not. Takes a boolean. Defaults to "true". If you disable it, systemd will not ratelimit messages written to kmsg. 🚦

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$SYSTEMD_PAGER, $PAGER

The pager to use when --no-pager isn't given. $SYSTEMD_PAGER wins if it's set; otherwise $PAGER is used. If neither $SYSTEMD_PAGER nor $PAGER are set, a set of well-known pager implementations gets tried in turn — including less(1) and more(1) — until one is found. If no pager implementation is discovered, no pager is invoked at all. 🫥

Setting either of those environment variables to an empty string or to the value "cat" is equivalent to passing --no-pager.

⚠️ Note: if $SYSTEMD_PAGERSECURE is not set, $SYSTEMD_PAGER and $PAGER can only be used to disable the pager (with "cat" or ""), and are otherwise ignored. No cap.

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$SYSTEMD_LESS

Overrides the options passed to less — by default that's "FRSXMK".

Two of those options are the ones people actually want to change:

• K — tells the pager to exit immediately when Ctrl+C is pressed. If you want less to handle Ctrl+C itself (to switch back to the pager command prompt), unset this option. If the value of $SYSTEMD_LESS does not include "K", and the pager invoked is less, Ctrl+C will be ignored by the executable and needs to be handled by the pager.
• X — tells the pager to not send termcap initialization and deinitialization strings to the terminal. It's set by default so command output stays visible in the terminal even after the pager exits. But — and this is the tradeoff — it prevents some pager functionality from working, in particular paged output cannot be scrolled with the mouse. 😭

⚠️ Setting the regular $LESS environment variable has no effect for less invocations by systemd tools. Rude but true.

See less(1) for more discussion.

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$SYSTEMD_LESSCHARSET

Overrides the charset passed to less — by default "utf-8", if the invoking terminal is determined to be UTF-8 compatible. 🌐

⚠️ Setting the regular $LESSCHARSET environment variable has no effect for less invocations by systemd tools.

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$SYSTEMD_PAGERSECURE

okay this one is the serious one, bestie, sit down for a sec. 🫶

Common pager commands like less(1), in addition to "paging" (i.e. scrolling through the output), support opening or writing to other files and running arbitrary shell commands. When commands are invoked with elevated privileges — for example under sudo(8) or pkexec(1) — the pager becomes a security boundary. Care must be taken that only programs with strictly limited functionality are used as pagers, and that unintended interactive features like opening or creating new files, or starting subprocesses, are not allowed. "Secure mode" for the pager may be enabled as described below, if the pager supports it (most pagers are not written in a way that takes this into consideration 😬). It is recommended to either explicitly enable "secure mode" or to completely disable the pager using --no-pager or PAGER=cat when allowing untrusted users to execute commands with elevated privileges.

This option takes a boolean argument. When set to true, the "secure mode" of the pager is enabled. In "secure mode", LESSSECURE=1 will be set when invoking the pager, which instructs the pager to disable commands that open or create new files or start new subprocesses. Currently only less(1) is known to understand this variable and implement "secure mode".

When set to false, no limitation is placed on the pager. Setting SYSTEMD_PAGERSECURE=0, or simply not removing it from the inherited environment, may allow the user to invoke arbitrary commands. 🚨

When $SYSTEMD_PAGERSECURE is not set, systemd tools attempt to automatically figure out whether "secure mode" should be enabled and whether the pager supports it. "Secure mode" is enabled if the effective UID is not the same as the owner of the login session — see geteuid(2) and sd_pid_get_owner_uid(3) — or when running under sudo(8) or similar tools ($SUDO_UID is set [2]). In those cases, SYSTEMD_PAGERSECURE=1 will be set, and pagers which are not known to implement "secure mode" will not be used at all. Note that this autodetection only covers the most common mechanisms to elevate privileges and is intended as convenience. It is recommended to explicitly set $SYSTEMD_PAGERSECURE or disable the pager.

⚠️ Note: if the $SYSTEMD_PAGER or $PAGER variables are to be honoured — other than to disable the pager — $SYSTEMD_PAGERSECURE must be set too.

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$SYSTEMD_COLORS

Takes a boolean argument, or a special value. By default (unset), systemd and related utilities will use colors in their output if possible. If $COLORTERM is set to "truecolor" or "24bit", 24-bit colors will be enabled, 256 colors otherwise — unless $NO_COLOR or $TERM indicates colors are disabled. 🎨

• true — same as unset, except that $NO_COLOR is ignored.
• false — the output will be monochrome. (sad, but valid)
• "16", "256", "24bit" — always use the base 16 ANSI colors, 256 colors, or 24 bit color, respectively.
• "auto-16", "auto-256", "auto-24bit" — use the given quantity of colours, subject to $TERM, and what the console is connected to.

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$SYSTEMD_URLIFY

The value must be a boolean. Controls whether clickable links should be generated in the output for terminal emulators that support this. 🔗 You can specify this to override the decision that systemd makes based on $TERM and other conditions.

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👀 SEE ALSO 👀

systemd(1), systemd-storage-block@.service(8), systemd-storage-fs@.service(8), varlinkctl(1), mount(8)

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📝 NOTES 📝

1. Varlink — https://varlink.org/
2. It is recommended for other tools to set and check $SUDO_UID as appropriate, treating it as a common interface.

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and that's the whole page bestie!! 🎀 you made it to the end, I'm so proud of you fr fr 💜

this was systemd 262.1 — the STORAGECTL(1) page. go forth and manage your storage, you absolute icon. slay. 💅✨