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docs/ENVIRONMENT: syntax highlighting and some rewordings
Use backticks for commands and functions and variables, suffix directories with a slash. Some sentences were reworded.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
parent
bfe6043454
commit
e7b86e4813
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@ -19,18 +19,17 @@ documented in the proper man pages.
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All tools:
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* `$SYSTEMD_OFFLINE=[0|1]` — if set to `1`, then `systemctl` will
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refrain from talking to PID 1; this has the same effect as the historical
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detection of `chroot()`. Setting this variable to `0` instead has a similar
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effect as `SYSTEMD_IGNORE_CHROOT=1`; i.e. tools will try to
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communicate with PID 1 even if a `chroot()` environment is detected.
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You almost certainly want to set this to `1` if you maintain a package build system
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or similar and are trying to use a modern container system and not plain
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`chroot()`.
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* `$SYSTEMD_OFFLINE=[0|1]` — if set to `1`, then `systemctl` will refrain from
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talking to PID 1; this has the same effect as the historical detection of
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`chroot()`. Setting this variable to `0` instead has a similar effect as
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`SYSTEMD_IGNORE_CHROOT=1`; i.e. tools will try to communicate with PID 1 even
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if a `chroot()` environment is detected. You almost certainly want to set
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this to `1` if you maintain a package build system or similar and are trying
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to use a modern container system and not plain `chroot()`.
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* `$SYSTEMD_IGNORE_CHROOT=1` — if set, don't check whether being invoked in a
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`chroot()` environment. This is particularly relevant for systemctl, as it
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will not alter its behaviour for `chroot()` environments if set. Normally it
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will not alter its behaviour for `chroot()` environments if set. Normally it
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refrains from talking to PID 1 in such a case; turning most operations such
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as `start` into no-ops. If that's what's explicitly desired, you might
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consider setting `SYSTEMD_OFFLINE=1`.
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@ -39,21 +38,23 @@ All tools:
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will print latency information at runtime.
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* `$SYSTEMD_PROC_CMDLINE` — if set, the contents are used as the kernel command
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line instead of the actual one in /proc/cmdline. This is useful for
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line instead of the actual one in `/proc/cmdline`. This is useful for
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debugging, in order to test generators and other code against specific kernel
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command lines.
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* `$SYSTEMD_FSTAB` — if set, use this path instead of /etc/fstab. Only useful
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* `$SYSTEMD_FSTAB` — if set, use this path instead of `/etc/fstab`. Only useful
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for debugging.
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* `$SYSTEMD_CRYPTTAB` — if set, use this path instead of /etc/crypttab. Only
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useful for debugging. Currently only supported by systemd-cryptsetup-generator.
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* `$SYSTEMD_CRYPTTAB` — if set, use this path instead of `/etc/crypttab`. Only
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useful for debugging. Currently only supported by
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`systemd-cryptsetup-generator`.
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* `$SYSTEMD_VERITYTAB` — if set, use this path instead of /etc/veritytab. Only
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useful for debugging. Currently only supported by systemd-veritysetup-generator.
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* `$SYSTEMD_VERITYTAB` — if set, use this path instead of
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`/etc/veritytab`. Only useful for debugging. Currently only supported by
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`systemd-veritysetup-generator`.
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* `$SYSTEMD_EFI_OPTIONS` — if set, used instead of the string in the
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SystemdOptions EFI variable. Analogous to `$SYSTEMD_PROC_CMDLINE`.
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`SystemdOptions` EFI variable. Analogous to `$SYSTEMD_PROC_CMDLINE`.
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* `$SYSTEMD_IN_INITRD=[auto|lenient|0|1]` — if set, specifies initrd detection
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method. Defaults to `auto`. Behavior is defined as follows:
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@ -69,23 +70,23 @@ All tools:
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to 0, then the built-in default is used.
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* `$SYSTEMD_MEMPOOL=0` — if set, the internal memory caching logic employed by
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hash tables is turned off, and libc malloc() is used for all allocations.
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hash tables is turned off, and libc `malloc()` is used for all allocations.
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* `$SYSTEMD_EMOJI=0` — if set, tools such as "systemd-analyze security" will
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* `$SYSTEMD_EMOJI=0` — if set, tools such as `systemd-analyze security` will
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not output graphical smiley emojis, but ASCII alternatives instead. Note that
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this only controls use of Unicode emoji glyphs, and has no effect on other
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Unicode glyphs.
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* `$RUNTIME_DIRECTORY` — various tools use this variable to locate the
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appropriate path under /run. This variable is also set by the manager when
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RuntimeDirectory= is used, see systemd.exec(5).
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appropriate path under `/run/`. This variable is also set by the manager when
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`RuntimeDirectory=` is used, see systemd.exec(5).
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* `$SYSTEMD_CRYPT_PREFIX` — if set configures the hash method prefix to use for
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UNIX crypt() when generating passwords. By default the system's "preferred
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method" is used, but this can be overridden with this environment
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variable. Takes a prefix such as `$6$` or `$y$`. (Note that this is only
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honoured on systems built with libxcrypt and is ignored on systems using
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glibc's original, internal crypt() implementation.)
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UNIX `crypt()` when generating passwords. By default the system's "preferred
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method" is used, but this can be overridden with this environment variable.
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Takes a prefix such as `$6$` or `$y$`. (Note that this is only honoured on
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systems built with libxcrypt and is ignored on systems using glibc's
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original, internal `crypt()` implementation.)
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* `$SYSTEMD_RDRAND=0` — if set, the RDRAND instruction will never be used,
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even if the CPU supports it.
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@ -94,10 +95,10 @@ All tools:
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support for it is compiled in and available in the kernel.
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* `$SYSTEMD_LOG_SECCOMP=1` — if set, system calls blocked by seccomp filtering,
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for example in systemd-nspawn, will be logged to the audit log, if the current
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kernel version supports this.
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for example in `systemd-nspawn`, will be logged to the audit log, if the
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kernel supports this.
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systemctl:
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`systemctl`:
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* `$SYSTEMCTL_FORCE_BUS=1` — if set, do not connect to PID1's private D-Bus
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listener, and instead always connect through the dbus-daemon D-bus broker.
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@ -105,16 +106,16 @@ systemctl:
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* `$SYSTEMCTL_INSTALL_CLIENT_SIDE=1` — if set, enable or disable unit files on
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the client side, instead of asking PID 1 to do this.
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* `$SYSTEMCTL_SKIP_SYSV=1` — if set, do not call out to SysV compatibility hooks.
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* `$SYSTEMCTL_SKIP_SYSV=1` — if set, do not call SysV compatibility hooks.
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systemd-nspawn:
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`systemd-nspawn`:
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* `$SYSTEMD_NSPAWN_UNIFIED_HIERARCHY=1` — if set, force nspawn into unified
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cgroup hierarchy mode.
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* `$SYSTEMD_NSPAWN_UNIFIED_HIERARCHY=1` — if set, force `systemd-nspawn` into
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unified cgroup hierarchy mode.
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* `$SYSTEMD_NSPAWN_API_VFS_WRITABLE=1` — if set, make /sys and /proc/sys and
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friends writable in the container. If set to "network", leave only
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/proc/sys/net writable.
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* `$SYSTEMD_NSPAWN_API_VFS_WRITABLE=1` — if set, make `/sys/`, `/proc/sys/`,
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and friends writable in the container. If set to "network", leave only
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`/proc/sys/net/` writable.
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* `$SYSTEMD_NSPAWN_CONTAINER_SERVICE=…` — override the "service" name nspawn
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uses to register with machined. If unset defaults to "nspawn", but with this
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@ -125,40 +126,41 @@ systemd-nspawn:
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* `$SYSTEMD_NSPAWN_LOCK=0` — if set, do not lock container images when running.
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* `$SYSTEMD_NSPAWN_TMPFS_TMP=0` — if set, do not overmount /tmp in the
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* `$SYSTEMD_NSPAWN_TMPFS_TMP=0` — if set, do not overmount `/tmp/` in the
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container with a tmpfs, but leave the directory from the image in place.
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systemd-logind:
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`systemd-logind`:
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* `$SYSTEMD_BYPASS_HIBERNATION_MEMORY_CHECK=1` — if set, report that
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hibernation is available even if the swap devices do not provide enough room
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for it.
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* `$SYSTEMD_REBOOT_TO_FIRMWARE_SETUP` — if set overrides systemd-logind's
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built-in EFI logic of requesting a reboot into the firmware. Takes a
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boolean. If set to false the functionality is turned off entirely. If set to
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true instead of requesting a reboot into the firmware setup UI through EFI a
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file `/run/systemd/reboot-to-firmware-setup` is created whenever this is
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* `$SYSTEMD_REBOOT_TO_FIRMWARE_SETUP` — if set, overrides `systemd-logind`'s
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built-in EFI logic of requesting a reboot into the firmware. Takes a boolean.
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If set to false, the functionality is turned off entirely. If set to true,
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instead of requesting a reboot into the firmware setup UI through EFI a file,
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`/run/systemd/reboot-to-firmware-setup` is created whenever this is
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requested. This file may be checked for by services run during system
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shutdown in order to request the appropriate operation from the firmware in
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an alternative fashion.
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* `$SYSTEMD_REBOOT_TO_BOOT_LOADER_MENU` — similar to the above, allows
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overriding of systemd-logind's built-in EFI logic of requesting a reboot into
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the boot loader menu. Takes a boolean. If set to false the functionality is
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turned off entirely. If set to true instead of requesting a reboot into the
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boot loader menu through EFI a file `/run/systemd/reboot-to-boot-loader-menu`
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is created whenever this is requested. The file contains the requested boot
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loader menu timeout in µs, formatted in ASCII decimals, or zero in case no
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timeout is requested. This file may be checked for by services run during
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system shutdown in order to request the appropriate operation from the boot
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loader in an alternative fashion.
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overriding of `systemd-logind`'s built-in EFI logic of requesting a reboot
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into the boot loader menu. Takes a boolean. If set to false, the
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functionality is turned off entirely. If set to true, instead of requesting a
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reboot into the boot loader menu through EFI, the file
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`/run/systemd/reboot-to-boot-loader-menu` is created whenever this is
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requested. The file contains the requested boot loader menu timeout in µs,
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formatted in ASCII decimals, or zero in case no timeout is requested. This
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file may be checked for by services run during system shutdown in order to
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request the appropriate operation from the boot loader in an alternative
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fashion.
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* `$SYSTEMD_REBOOT_TO_BOOT_LOADER_ENTRY` — similar to the above, allows
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overriding of systemd-logind's built-in EFI logic of requesting a reboot into
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a specific boot loader entry. Takes a boolean. If set to false the
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functionality is turned off entirely. If set to true instead of requesting a
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reboot into a specific boot loader entry through EFI a file
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overriding of `systemd-logind`'s built-in EFI logic of requesting a reboot
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into a specific boot loader entry. Takes a boolean. If set to false, the
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functionality is turned off entirely. If set to true, instead of requesting a
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reboot into a specific boot loader entry through EFI, the file
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`/run/systemd/reboot-to-boot-loader-entry` is created whenever this is
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requested. The file contains the requested boot loader entry identifier. This
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file may be checked for by services run during system shutdown in order to
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@ -173,30 +175,31 @@ systemd-logind:
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`/run/boot-loader-entries/loader/entries/*.conf`, and the files referenced by
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the drop-ins (including the kernels and initrds) somewhere else below
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`/run/boot-loader-entries/`. Note that all these files may be (and are
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supposed to be) symlinks. systemd-logind will load these files on-demand,
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supposed to be) symlinks. `systemd-logind` will load these files on-demand,
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these files can hence be updated (ideally atomically) whenever the boot
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loader configuration changes. A foreign boot loader installer script should
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hence synthesize drop-in snippets and symlinks for all boot entries at boot
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or whenever they change if it wants to integrate with systemd-logind's APIs.
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or whenever they change if it wants to integrate with `systemd-logind`'s
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APIs.
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systemd-udevd:
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`systemd-udevd`:
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* `$NET_NAMING_SCHEME=` – if set, takes a network naming scheme (i.e. one of
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"v238", "v239", "v240"…, or the special value "latest") as parameter. If
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specified udev's net_id builtin will follow the specified naming scheme when
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determining stable network interface names. This may be used to revert to
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naming schemes of older udev versions, in order to provide more stable naming
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across updates. This environment variable takes precedence over the kernel
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command line option `net.naming-scheme=`, except if the value is prefixed
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with `:` in which case the kernel command line option takes precedence, if it
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is specified as well.
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specified udev's `net_id` builtin will follow the specified naming scheme
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when determining stable network interface names. This may be used to revert
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to naming schemes of older udev versions, in order to provide more stable
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naming across updates. This environment variable takes precedence over the
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kernel command line option `net.naming-scheme=`, except if the value is
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prefixed with `:` in which case the kernel command line option takes
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precedence, if it is specified as well.
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installed systemd tests:
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* `$SYSTEMD_TEST_DATA` — override the location of test data. This is useful if
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a test executable is moved to an arbitrary location.
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nss-systemd:
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`nss-systemd`:
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* `$SYSTEMD_NSS_BYPASS_SYNTHETIC=1` — if set, `nss-systemd` won't synthesize
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user/group records for the `root` and `nobody` users if they are missing from
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@ -210,20 +213,20 @@ nss-systemd:
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dynamic user lookups. This is primarily useful to make `nss-systemd` work
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safely from within `dbus-daemon`.
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systemd-timedated:
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`systemd-timedated`:
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* `$SYSTEMD_TIMEDATED_NTP_SERVICES=…` — colon-separated list of unit names of
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NTP client services. If set, `timedatectl set-ntp on` enables and starts the
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first existing unit listed in the environment variable, and
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`timedatectl set-ntp off` disables and stops all listed units.
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systemd-sulogin-shell:
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`systemd-sulogin-shell`:
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* `$SYSTEMD_SULOGIN_FORCE=1` — This skips asking for the root password if the
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root password is not available (such as when the root account is locked).
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See `sulogin(8)` for more details.
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bootctl and other tools that access the EFI System Partition (ESP):
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`bootctl` and other tools that access the EFI System Partition (ESP):
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* `$SYSTEMD_RELAX_ESP_CHECKS=1` — if set, the ESP validation checks are
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relaxed. Specifically, validation checks that ensure the specified ESP path
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@ -232,11 +235,11 @@ bootctl and other tools that access the EFI System Partition (ESP):
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* `$SYSTEMD_ESP_PATH=…` — override the path to the EFI System Partition. This
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may be used to override ESP path auto detection, and redirect any accesses to
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the ESP to the specified directory. Not that unlike with bootctl's --path=
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switch only very superficial validation of the specified path is done when
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this environment variable is used.
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the ESP to the specified directory. Note that unlike with `bootctl`'s
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`--path=` switch only very superficial validation of the specified path is
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done when this environment variable is used.
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systemd itself:
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`systemd` itself:
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* `$SYSTEMD_ACTIVATION_UNIT` — set for all NSS and PAM module invocations that
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are done by the service manager on behalf of a specific unit, in child
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@ -254,34 +257,35 @@ systemd itself:
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it is either set to `system` or `user` depending on whether the NSS/PAM
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module is called by systemd in `--system` or `--user` mode.
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systemd-remount-fs:
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`systemd-remount-fs`:
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* `$SYSTEMD_REMOUNT_ROOT_RW=1` — if set and no entry for the root directory
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exists in /etc/fstab (this file always takes precedence), then the root
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exists in `/etc/fstab` (this file always takes precedence), then the root
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directory is remounted writable. This is primarily used by
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systemd-gpt-auto-generator to ensure the root partition is mounted writable
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`systemd-gpt-auto-generator` to ensure the root partition is mounted writable
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in accordance to the GPT partition flags.
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systemd-firstboot and localectl:
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`systemd-firstboot` and `localectl`:
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* `SYSTEMD_LIST_NON_UTF8_LOCALES=1` – if set non-UTF-8 locales are listed among
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* `SYSTEMD_LIST_NON_UTF8_LOCALES=1` – if set, non-UTF-8 locales are listed among
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the installed ones. By default non-UTF-8 locales are suppressed from the
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selection, since we are living in the 21st century.
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systemd-sysext:
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`systemd-sysext`:
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* `SYSTEMD_SYSEXT_HIERARCHIES` – if set to a colon-separated list of absolute
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paths this variable may be used to override which hierarchies to manage with
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`systemd-sysext`. By default only `/usr/` and `/opt/` are managed. With this
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environment variable this list may be changed, in order to add or remove
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directories from this list. This should only reference "real" file systems
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and directories that only contain "real" file systems as submounts — do not
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specify API file systems such as `/proc/` or `/sys/` here, or hierarchies
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that have them as submounts. In particular, do not specify the root directory
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`/` here.
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* `SYSTEMD_SYSEXT_HIERARCHIES` – this variable may be used to override which
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hierarchies are managed by `systemd-sysext`. By default only `/usr/` and
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`/opt/` are managed, and directories may be added or removed to that list by
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setting this environment variable to a colon-separated list of absolute
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paths. Only "real" file systems and directories that only contain "real" file
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systems as submounts should be used. Do not specify API file systems such as
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`/proc/` or `/sys/` here, or hierarchies that have them as submounts. In
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particular, do not specify the root directory `/` here.
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systemd-tmpfiles:
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`systemd-tmpfiles`:
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* `SYSTEMD_TMPFILES_FORCE_SUBVOL` - if unset, v/q/Q lines will create subvolumes only if the
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OS itself is installed into a subvolume. If set to 1 (or another true value), these lines will always create
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subvolumes (if the backing filesystem supports them). If set to 0, these lines will always create directories.
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* `SYSTEMD_TMPFILES_FORCE_SUBVOL` - if unset, `v`/`q`/`Q` lines will create
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subvolumes only if the OS itself is installed into a subvolume. If set to `1`
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(or another value interpreted as true), these lines will always create
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subvolumes if the backing filesystem supports them. If set to `0`, these
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lines will always create directories.
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