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c3e270f4 FB |
1 | --- |
2 | title: Known Environment Variables | |
4cdca0af | 3 | category: Interfaces |
b41a3f66 | 4 | layout: default |
0aff7b75 | 5 | SPDX-License-Identifier: LGPL-2.1-or-later |
c3e270f4 FB |
6 | --- |
7 | ||
4549fcdb LP |
8 | # Known Environment Variables |
9 | ||
10 | A number of systemd components take additional runtime parameters via | |
11 | environment variables. Many of these environment variables are not supported at | |
12 | the same level as command line switches and other interfaces are: we don't | |
13 | document them in the man pages and we make no stability guarantees for | |
14 | them. While they generally are unlikely to be dropped any time soon again, we | |
15 | do not want to guarantee that they stay around for good either. | |
16 | ||
17 | Below is an (incomprehensive) list of the environment variables understood by | |
18 | the various tools. Note that this list only covers environment variables not | |
19 | documented in the proper man pages. | |
20 | ||
21 | All tools: | |
22 | ||
e7b86e48 ZJS |
23 | * `$SYSTEMD_OFFLINE=[0|1]` — if set to `1`, then `systemctl` will refrain from |
24 | talking to PID 1; this has the same effect as the historical detection of | |
25 | `chroot()`. Setting this variable to `0` instead has a similar effect as | |
54dcf847 LP |
26 | `$SYSTEMD_IGNORE_CHROOT=1`; i.e. tools will try to communicate with PID 1 |
27 | even if a `chroot()` environment is detected. You almost certainly want to | |
28 | set this to `1` if you maintain a package build system or similar and are | |
29 | trying to use a modern container system and not plain `chroot()`. | |
f38951a6 | 30 | |
4549fcdb | 31 | * `$SYSTEMD_IGNORE_CHROOT=1` — if set, don't check whether being invoked in a |
f38951a6 | 32 | `chroot()` environment. This is particularly relevant for systemctl, as it |
e7b86e48 | 33 | will not alter its behaviour for `chroot()` environments if set. Normally it |
f38951a6 CW |
34 | refrains from talking to PID 1 in such a case; turning most operations such |
35 | as `start` into no-ops. If that's what's explicitly desired, you might | |
54dcf847 | 36 | consider setting `$SYSTEMD_OFFLINE=1`. |
4549fcdb LP |
37 | |
38 | * `$SD_EVENT_PROFILE_DELAYS=1` — if set, the sd-event event loop implementation | |
39 | will print latency information at runtime. | |
40 | ||
53aa0d02 | 41 | * `$SYSTEMD_PROC_CMDLINE` — if set, the contents are used as the kernel command |
e7b86e48 | 42 | line instead of the actual one in `/proc/cmdline`. This is useful for |
53aa0d02 ZJS |
43 | debugging, in order to test generators and other code against specific kernel |
44 | command lines. | |
45 | ||
df78419d ZJS |
46 | * `$SYSTEMD_OS_RELEASE` — if set, use this path instead of `/etc/os-release` or |
47 | `/usr/lib/os-release`. When operating under some root (e.g. `systemctl | |
48 | --root=…`), the path is taken relative to the outside root. Only useful for | |
49 | debugging. | |
50 | ||
e7b86e48 | 51 | * `$SYSTEMD_FSTAB` — if set, use this path instead of `/etc/fstab`. Only useful |
ed4ad488 ZJS |
52 | for debugging. |
53 | ||
e7b86e48 ZJS |
54 | * `$SYSTEMD_CRYPTTAB` — if set, use this path instead of `/etc/crypttab`. Only |
55 | useful for debugging. Currently only supported by | |
56 | `systemd-cryptsetup-generator`. | |
a6c57e74 | 57 | |
1f1a2243 TA |
58 | * `$SYSTEMD_INTEGRITYTAB` — if set, use this path instead of |
59 | `/etc/integritytab`. Only useful for debugging. Currently only supported by | |
60 | `systemd-integritysetup-generator`. | |
61 | ||
e7b86e48 ZJS |
62 | * `$SYSTEMD_VERITYTAB` — if set, use this path instead of |
63 | `/etc/veritytab`. Only useful for debugging. Currently only supported by | |
64 | `systemd-veritysetup-generator`. | |
08b04ec7 | 65 | |
2536752d | 66 | * `$SYSTEMD_EFI_OPTIONS` — if set, used instead of the string in the |
e7b86e48 | 67 | `SystemdOptions` EFI variable. Analogous to `$SYSTEMD_PROC_CMDLINE`. |
2467cc55 | 68 | |
05c6f341 ZJS |
69 | * `$SYSTEMD_DEFAULT_HOSTNAME` — override the compiled-in fallback hostname |
70 | (relevant in particular for the system manager and `systemd-hostnamed`). | |
71 | Must be a valid hostname (either a single label or a FQDN). | |
72 | ||
1f22621b KS |
73 | * `$SYSTEMD_IN_INITRD=[auto|lenient|0|1]` — if set, specifies initrd detection |
74 | method. Defaults to `auto`. Behavior is defined as follows: | |
75 | `auto`: Checks if `/etc/initrd-release` exists, and a temporary fs is mounted | |
76 | on `/`. If both conditions meet, then it's in initrd. | |
38f3e0a5 | 77 | `lenient`: Similar to `auto`, but the rootfs check is skipped. |
1f22621b KS |
78 | `0|1`: Simply overrides initrd detection. This is useful for debugging and |
79 | testing initrd-only programs in the main system. | |
0307ea49 | 80 | |
385b2eb2 YW |
81 | * `$SYSTEMD_BUS_TIMEOUT=SECS` — specifies the maximum time to wait for method call |
82 | completion. If no time unit is specified, assumes seconds. The usual other units | |
83 | are understood, too (us, ms, s, min, h, d, w, month, y). If it is not set or set | |
84 | to 0, then the built-in default is used. | |
85 | ||
5f1b0cc6 | 86 | * `$SYSTEMD_MEMPOOL=0` — if set, the internal memory caching logic employed by |
e7b86e48 | 87 | hash tables is turned off, and libc `malloc()` is used for all allocations. |
b4f60743 | 88 | |
e7b86e48 | 89 | * `$SYSTEMD_EMOJI=0` — if set, tools such as `systemd-analyze security` will |
5f1b0cc6 LP |
90 | not output graphical smiley emojis, but ASCII alternatives instead. Note that |
91 | this only controls use of Unicode emoji glyphs, and has no effect on other | |
92 | Unicode glyphs. | |
93 | ||
3f5ac303 | 94 | * `$RUNTIME_DIRECTORY` — various tools use this variable to locate the |
e7b86e48 ZJS |
95 | appropriate path under `/run/`. This variable is also set by the manager when |
96 | `RuntimeDirectory=` is used, see systemd.exec(5). | |
3f5ac303 | 97 | |
42f3b2f9 | 98 | * `$SYSTEMD_CRYPT_PREFIX` — if set configures the hash method prefix to use for |
e7b86e48 ZJS |
99 | UNIX `crypt()` when generating passwords. By default the system's "preferred |
100 | method" is used, but this can be overridden with this environment variable. | |
101 | Takes a prefix such as `$6$` or `$y$`. (Note that this is only honoured on | |
102 | systems built with libxcrypt and is ignored on systems using glibc's | |
103 | original, internal `crypt()` implementation.) | |
42f3b2f9 | 104 | |
54dcf847 | 105 | * `$SYSTEMD_SECCOMP=0` — if set, seccomp filters will not be enforced, even if |
ce8f6d47 LP |
106 | support for it is compiled in and available in the kernel. |
107 | ||
108 | * `$SYSTEMD_LOG_SECCOMP=1` — if set, system calls blocked by seccomp filtering, | |
e7b86e48 ZJS |
109 | for example in `systemd-nspawn`, will be logged to the audit log, if the |
110 | kernel supports this. | |
ce8f6d47 | 111 | |
e7b86e48 | 112 | `systemctl`: |
4549fcdb | 113 | |
8f1a581e | 114 | * `$SYSTEMCTL_FORCE_BUS=1` — if set, do not connect to PID 1's private D-Bus |
4549fcdb LP |
115 | listener, and instead always connect through the dbus-daemon D-bus broker. |
116 | ||
117 | * `$SYSTEMCTL_INSTALL_CLIENT_SIDE=1` — if set, enable or disable unit files on | |
118 | the client side, instead of asking PID 1 to do this. | |
119 | ||
e7b86e48 | 120 | * `$SYSTEMCTL_SKIP_SYSV=1` — if set, do not call SysV compatibility hooks. |
4549fcdb | 121 | |
e7b86e48 | 122 | `systemd-nspawn`: |
4549fcdb | 123 | |
e7b86e48 ZJS |
124 | * `$SYSTEMD_NSPAWN_UNIFIED_HIERARCHY=1` — if set, force `systemd-nspawn` into |
125 | unified cgroup hierarchy mode. | |
4549fcdb | 126 | |
e7b86e48 ZJS |
127 | * `$SYSTEMD_NSPAWN_API_VFS_WRITABLE=1` — if set, make `/sys/`, `/proc/sys/`, |
128 | and friends writable in the container. If set to "network", leave only | |
129 | `/proc/sys/net/` writable. | |
4549fcdb LP |
130 | |
131 | * `$SYSTEMD_NSPAWN_CONTAINER_SERVICE=…` — override the "service" name nspawn | |
132 | uses to register with machined. If unset defaults to "nspawn", but with this | |
133 | variable may be set to any other value. | |
134 | ||
135 | * `$SYSTEMD_NSPAWN_USE_CGNS=0` — if set, do not use cgroup namespacing, even if | |
136 | it is available. | |
137 | ||
138 | * `$SYSTEMD_NSPAWN_LOCK=0` — if set, do not lock container images when running. | |
139 | ||
e7b86e48 | 140 | * `$SYSTEMD_NSPAWN_TMPFS_TMP=0` — if set, do not overmount `/tmp/` in the |
1099ceeb LP |
141 | container with a tmpfs, but leave the directory from the image in place. |
142 | ||
4a4654e0 LP |
143 | * `$SYSTEMD_SUPPRESS_SYNC=1` — if set, all disk synchronization syscalls are |
144 | blocked to the container payload (e.g. `sync()`, `fsync()`, `syncfs()`, …) | |
145 | and the `O_SYNC`/`O_DSYNC` flags are made unavailable to `open()` and | |
146 | friends. This is equivalent to passing `--suppress-sync=yes` on the | |
147 | `systemd-nspawn` command line. | |
148 | ||
e7b86e48 | 149 | `systemd-logind`: |
4549fcdb LP |
150 | |
151 | * `$SYSTEMD_BYPASS_HIBERNATION_MEMORY_CHECK=1` — if set, report that | |
152 | hibernation is available even if the swap devices do not provide enough room | |
153 | for it. | |
94fa1497 | 154 | |
e7b86e48 ZJS |
155 | * `$SYSTEMD_REBOOT_TO_FIRMWARE_SETUP` — if set, overrides `systemd-logind`'s |
156 | built-in EFI logic of requesting a reboot into the firmware. Takes a boolean. | |
157 | If set to false, the functionality is turned off entirely. If set to true, | |
158 | instead of requesting a reboot into the firmware setup UI through EFI a file, | |
159 | `/run/systemd/reboot-to-firmware-setup` is created whenever this is | |
e86c7a3a LP |
160 | requested. This file may be checked for by services run during system |
161 | shutdown in order to request the appropriate operation from the firmware in | |
162 | an alternative fashion. | |
163 | ||
164 | * `$SYSTEMD_REBOOT_TO_BOOT_LOADER_MENU` — similar to the above, allows | |
e7b86e48 ZJS |
165 | overriding of `systemd-logind`'s built-in EFI logic of requesting a reboot |
166 | into the boot loader menu. Takes a boolean. If set to false, the | |
167 | functionality is turned off entirely. If set to true, instead of requesting a | |
168 | reboot into the boot loader menu through EFI, the file | |
169 | `/run/systemd/reboot-to-boot-loader-menu` is created whenever this is | |
170 | requested. The file contains the requested boot loader menu timeout in µs, | |
171 | formatted in ASCII decimals, or zero in case no timeout is requested. This | |
172 | file may be checked for by services run during system shutdown in order to | |
173 | request the appropriate operation from the boot loader in an alternative | |
174 | fashion. | |
e86c7a3a LP |
175 | |
176 | * `$SYSTEMD_REBOOT_TO_BOOT_LOADER_ENTRY` — similar to the above, allows | |
e7b86e48 ZJS |
177 | overriding of `systemd-logind`'s built-in EFI logic of requesting a reboot |
178 | into a specific boot loader entry. Takes a boolean. If set to false, the | |
179 | functionality is turned off entirely. If set to true, instead of requesting a | |
180 | reboot into a specific boot loader entry through EFI, the file | |
e86c7a3a LP |
181 | `/run/systemd/reboot-to-boot-loader-entry` is created whenever this is |
182 | requested. The file contains the requested boot loader entry identifier. This | |
183 | file may be checked for by services run during system shutdown in order to | |
184 | request the appropriate operation from the boot loader in an alternative | |
5c90c67a BF |
185 | fashion. Note that by default only boot loader entries which follow the |
186 | [Boot Loader Specification](BOOT_LOADER_SPECIFICATION.md) and are | |
e86c7a3a LP |
187 | placed in the ESP or the Extended Boot Loader partition may be selected this |
188 | way. However, if a directory `/run/boot-loader-entries/` exists, the entries | |
189 | are loaded from there instead. The directory should contain the usual | |
190 | directory hierarchy mandated by the Boot Loader Specification, i.e. the entry | |
191 | drop-ins should be placed in | |
192 | `/run/boot-loader-entries/loader/entries/*.conf`, and the files referenced by | |
193 | the drop-ins (including the kernels and initrds) somewhere else below | |
194 | `/run/boot-loader-entries/`. Note that all these files may be (and are | |
e7b86e48 | 195 | supposed to be) symlinks. `systemd-logind` will load these files on-demand, |
e86c7a3a LP |
196 | these files can hence be updated (ideally atomically) whenever the boot |
197 | loader configuration changes. A foreign boot loader installer script should | |
198 | hence synthesize drop-in snippets and symlinks for all boot entries at boot | |
e7b86e48 ZJS |
199 | or whenever they change if it wants to integrate with `systemd-logind`'s |
200 | APIs. | |
e86c7a3a | 201 | |
a7910612 | 202 | `systemd-udevd` and sd-device library: |
679dab6a | 203 | |
54dcf847 | 204 | * `$NET_NAMING_SCHEME=` — if set, takes a network naming scheme (i.e. one of |
679dab6a | 205 | "v238", "v239", "v240"…, or the special value "latest") as parameter. If |
e7b86e48 ZJS |
206 | specified udev's `net_id` builtin will follow the specified naming scheme |
207 | when determining stable network interface names. This may be used to revert | |
208 | to naming schemes of older udev versions, in order to provide more stable | |
209 | naming across updates. This environment variable takes precedence over the | |
210 | kernel command line option `net.naming-scheme=`, except if the value is | |
211 | prefixed with `:` in which case the kernel command line option takes | |
212 | precedence, if it is specified as well. | |
679dab6a | 213 | |
a7910612 LP |
214 | * `$SYSTEMD_DEVICE_VERIFY_SYSFS` — if set to "0", disables verification that |
215 | devices sysfs path are actually backed by sysfs. Relaxing this verification | |
216 | is useful for testing purposes. | |
217 | ||
e7b86e48 | 218 | `nss-systemd`: |
dba1bd43 LP |
219 | |
220 | * `$SYSTEMD_NSS_BYPASS_SYNTHETIC=1` — if set, `nss-systemd` won't synthesize | |
221 | user/group records for the `root` and `nobody` users if they are missing from | |
222 | `/etc/passwd`. | |
223 | ||
224 | * `$SYSTEMD_NSS_DYNAMIC_BYPASS=1` — if set, `nss-systemd` won't return | |
225 | user/group records for dynamically registered service users (i.e. users | |
226 | registered through `DynamicUser=1`). | |
227 | ||
e7b86e48 | 228 | `systemd-timedated`: |
41d0da0f YW |
229 | |
230 | * `$SYSTEMD_TIMEDATED_NTP_SERVICES=…` — colon-separated list of unit names of | |
231 | NTP client services. If set, `timedatectl set-ntp on` enables and starts the | |
232 | first existing unit listed in the environment variable, and | |
233 | `timedatectl set-ntp off` disables and stops all listed units. | |
39922217 | 234 | |
e7b86e48 | 235 | `systemd-sulogin-shell`: |
33eb44fe AH |
236 | |
237 | * `$SYSTEMD_SULOGIN_FORCE=1` — This skips asking for the root password if the | |
238 | root password is not available (such as when the root account is locked). | |
239 | See `sulogin(8)` for more details. | |
240 | ||
e7b86e48 | 241 | `bootctl` and other tools that access the EFI System Partition (ESP): |
8cbb7d87 LP |
242 | |
243 | * `$SYSTEMD_RELAX_ESP_CHECKS=1` — if set, the ESP validation checks are | |
244 | relaxed. Specifically, validation checks that ensure the specified ESP path | |
245 | is a FAT file system are turned off, as are checks that the path is located | |
246 | on a GPT partition with the correct type UUID. | |
247 | ||
cc7a0bfa LP |
248 | * `$SYSTEMD_ESP_PATH=…` — override the path to the EFI System Partition. This |
249 | may be used to override ESP path auto detection, and redirect any accesses to | |
e7b86e48 ZJS |
250 | the ESP to the specified directory. Note that unlike with `bootctl`'s |
251 | `--path=` switch only very superficial validation of the specified path is | |
252 | done when this environment variable is used. | |
cc7a0bfa | 253 | |
e7b86e48 | 254 | `systemd` itself: |
39922217 LP |
255 | |
256 | * `$SYSTEMD_ACTIVATION_UNIT` — set for all NSS and PAM module invocations that | |
257 | are done by the service manager on behalf of a specific unit, in child | |
258 | processes that are later (after execve()) going to become unit | |
259 | processes. Contains the full unit name (e.g. "foobar.service"). NSS and PAM | |
260 | modules can use this information to determine in which context and on whose | |
261 | behalf they are being called, which may be useful to avoid deadlocks, for | |
262 | example to bypass IPC calls to the very service that is about to be | |
263 | started. Note that NSS and PAM modules should be careful to only rely on this | |
264 | data when invoked privileged, or possibly only when getppid() returns 1, as | |
265 | setting environment variables is of course possible in any even unprivileged | |
266 | contexts. | |
267 | ||
268 | * `$SYSTEMD_ACTIVATION_SCOPE` — closely related to `$SYSTEMD_ACTIVATION_UNIT`, | |
269 | it is either set to `system` or `user` depending on whether the NSS/PAM | |
270 | module is called by systemd in `--system` or `--user` mode. | |
59f13dd6 | 271 | |
e7b86e48 | 272 | `systemd-remount-fs`: |
59f13dd6 | 273 | |
d238709c | 274 | * `$SYSTEMD_REMOUNT_ROOT_RW=1` — if set and no entry for the root directory |
e7b86e48 | 275 | exists in `/etc/fstab` (this file always takes precedence), then the root |
59f13dd6 | 276 | directory is remounted writable. This is primarily used by |
e7b86e48 | 277 | `systemd-gpt-auto-generator` to ensure the root partition is mounted writable |
59f13dd6 | 278 | in accordance to the GPT partition flags. |
a7d9fccd | 279 | |
e7b86e48 | 280 | `systemd-firstboot` and `localectl`: |
a7d9fccd | 281 | |
54dcf847 | 282 | * `$SYSTEMD_LIST_NON_UTF8_LOCALES=1` — if set, non-UTF-8 locales are listed among |
a7d9fccd LP |
283 | the installed ones. By default non-UTF-8 locales are suppressed from the |
284 | selection, since we are living in the 21st century. | |
7a87fb61 | 285 | |
e7b86e48 | 286 | `systemd-sysext`: |
7a87fb61 | 287 | |
54dcf847 | 288 | * `$SYSTEMD_SYSEXT_HIERARCHIES` — this variable may be used to override which |
e7b86e48 ZJS |
289 | hierarchies are managed by `systemd-sysext`. By default only `/usr/` and |
290 | `/opt/` are managed, and directories may be added or removed to that list by | |
291 | setting this environment variable to a colon-separated list of absolute | |
292 | paths. Only "real" file systems and directories that only contain "real" file | |
293 | systems as submounts should be used. Do not specify API file systems such as | |
294 | `/proc/` or `/sys/` here, or hierarchies that have them as submounts. In | |
295 | particular, do not specify the root directory `/` here. | |
4368c60c | 296 | |
e7b86e48 | 297 | `systemd-tmpfiles`: |
4368c60c | 298 | |
54dcf847 | 299 | * `$SYSTEMD_TMPFILES_FORCE_SUBVOL` — if unset, `v`/`q`/`Q` lines will create |
e7b86e48 ZJS |
300 | subvolumes only if the OS itself is installed into a subvolume. If set to `1` |
301 | (or another value interpreted as true), these lines will always create | |
302 | subvolumes if the backing filesystem supports them. If set to `0`, these | |
303 | lines will always create directories. | |
07dc08c2 ZJS |
304 | |
305 | `systemd-sysv-generator`: | |
306 | ||
307 | * `$SYSTEMD_SYSVINIT_PATH` — Controls where `systemd-sysv-generator` looks for | |
308 | SysV init scripts. | |
309 | ||
310 | * `$SYSTEMD_SYSVRCND_PATH` — Controls where `systemd-sysv-generator` looks for | |
311 | SysV init script runlevel link farms. | |
48eb2af6 | 312 | |
f0cb09bb ZJS |
313 | systemd tests: |
314 | ||
315 | * `$SYSTEMD_TEST_DATA` — override the location of test data. This is useful if | |
316 | a test executable is moved to an arbitrary location. | |
317 | ||
318 | * `$SYSTEMD_TEST_NSS_BUFSIZE` — size of scratch buffers for "reentrant" | |
319 | functions exported by the nss modules. | |
320 | ||
48eb2af6 ZJS |
321 | fuzzers: |
322 | ||
323 | * `$SYSTEMD_FUZZ_OUTPUT` — A boolean that specifies whether to write output to | |
324 | stdout. Setting to true is useful in manual invocations, since all output is | |
325 | suppressed by default. | |
326 | ||
327 | * `$SYSTEMD_FUZZ_RUNS` — The number of times execution should be repeated in | |
328 | manual invocations. | |
329 | ||
f223fd6a | 330 | Note that it may be also useful to set `$SYSTEMD_LOG_LEVEL`, since all logging |
48eb2af6 | 331 | is suppressed by default. |
23851640 | 332 | |
54dcf847 | 333 | `systemd-importd`: |
23851640 | 334 | |
54dcf847 | 335 | * `$SYSTEMD_IMPORT_BTRFS_SUBVOL` — takes a boolean, which controls whether to |
23851640 LP |
336 | prefer creating btrfs subvolumes over plain directories for machine |
337 | images. Has no effect on non-btrfs file systems where subvolumes are not | |
338 | available anyway. If not set, defaults to true. | |
339 | ||
54dcf847 | 340 | * `$SYSTEMD_IMPORT_BTRFS_QUOTA` — takes a boolean, which controls whether to set |
23851640 LP |
341 | up quota automatically for created btrfs subvolumes for machine images. If |
342 | not set, defaults to true. Has no effect if machines are placed in regular | |
343 | directories, because btrfs subvolumes are not supported or disabled. If | |
344 | enabled, the quota group of the subvolume is automatically added to a | |
345 | combined quota group for all such machine subvolumes. | |
346 | ||
54dcf847 | 347 | * `$SYSTEMD_IMPORT_SYNC` — takes a boolean, which controls whether to |
23851640 LP |
348 | synchronize images to disk after installing them, before completing the |
349 | operation. If not set, defaults to true. If disabled installation of images | |
350 | will be quicker, but not as safe. | |
54dcf847 LP |
351 | |
352 | `systemd-dissect`, `systemd-nspawn` and all other tools that may operate on | |
353 | disk images with `--image=` or similar: | |
354 | ||
355 | * `$SYSTEMD_DISSECT_VERITY_SIDECAR` — takes a boolean, which controls whether to | |
356 | load "sidecar" Verity metadata files. If enabled (which is the default), | |
357 | whenever a disk image is used, a set of files with the `.roothash`, | |
358 | `.usrhash`, `.roothash.p7s`, `.usrhash.p7s`, `.verity` suffixes are searched | |
359 | adjacent to disk image file, containing the Verity root hashes, their | |
360 | signatures or the Verity data itself. If disabled this automatic discovery of | |
361 | Verity metadata files is turned off. | |
362 | ||
363 | * `$SYSTEMD_DISSECT_VERITY_EMBEDDED` — takes a boolean, which controls whether | |
364 | to load the embedded Verity signature data. If enabled (which is the | |
365 | default), Verity root hash information and a suitable signature is | |
366 | automatically acquired from a signature partition, following the | |
5c90c67a BF |
367 | [Discoverable Partitions Specification](DISCOVERABLE_PARTITIONS.md). |
368 | If disabled any such partition is ignored. Note that this only disables | |
369 | discovery of the root hash and its signature, the Verity data partition | |
370 | itself is still searched in the GPT image. | |
54dcf847 LP |
371 | |
372 | * `$SYSTEMD_DISSECT_VERITY_SIGNATURE` — takes a boolean, which controls whether | |
373 | to validate the signature of the Verity root hash if available. If enabled | |
374 | (which is the default), the signature of suitable disk images is validated | |
375 | against any of the certificates in `/etc/verity.d/*.crt` (and similar | |
ba669952 | 376 | directories in `/usr/lib/`, `/run`, …) or passed to the kernel for validation |
54dcf847 | 377 | against its built-in certificates. |
ccd25f41 | 378 | |
e8c7c4d9 LP |
379 | * `$SYSTEMD_LOOP_DIRECT_IO` – takes a boolean, which controls whether to enable |
380 | LO_FLAGS_DIRECT_IO (i.e. direct IO + asynchronous IO) on loopback block | |
381 | devices when opening them. Defaults to on, set this to "0" to disable this | |
382 | feature. | |
383 | ||
ccd25f41 LP |
384 | `systemd-cryptsetup`: |
385 | ||
386 | * `$SYSTEMD_CRYPTSETUP_USE_TOKEN_MODULE` – takes a boolean, which controls | |
387 | whether to use the libcryptsetup "token" plugin module logic even when | |
388 | activating via FIDO2, PKCS#11, TPM2, i.e. mechanisms natively supported by | |
389 | `systemd-cryptsetup`. Defaults to enabled. | |
c04358ce LP |
390 | |
391 | Various tools that read passwords from the TTY, such as `systemd-cryptenroll` | |
392 | and `homectl`: | |
393 | ||
394 | * `$PASSWORD` — takes a string: the literal password to use. If this | |
395 | environment variable is set it is used as password instead of prompting the | |
396 | user interactively. This exists primarily for debugging and testing | |
397 | purposes. Do not use this for production code paths, since environment | |
398 | variables are typically inherited down the process tree without restrictions | |
399 | and should thus not be used for secrets. | |
400 | ||
401 | * `$NEWPASSWORD` — similar to `$PASSWORD` above, but is used when both a | |
402 | current and a future password are required, for example if the password is to | |
403 | be changed. In that case `$PASSWORD` shall carry the current (i.e. old) | |
404 | password and `$NEWPASSWORD` the new. | |
67302b38 LP |
405 | |
406 | `systemd-homed`: | |
407 | ||
408 | * `$SYSTEMD_HOME_ROOT` – defines an absolute path where to look for home | |
409 | directories/images. When unspecified defaults to `/home/`. This is useful for | |
410 | debugging purposes in order to run a secondary `systemd-homed` instance that | |
411 | operates on a different directory where home directories/images are placed. | |
412 | ||
413 | * `$SYSTEMD_HOME_RECORD_DIR` – defines an absolute path where to look for | |
414 | fixated home records kept on the host. When unspecified defaults to | |
415 | `/var/lib/systemd/home/`. Similar to `$SYSTEMD_HOME_ROOT` this is useful for | |
416 | debugging purposes, in order to run a secondary `systemd-homed` instance that | |
417 | operates on a record database entirely separate from the host's. | |
418 | ||
419 | * `$SYSTEMD_HOME_DEBUG_SUFFIX` – takes a short string that is suffixed to | |
420 | `systemd-homed`'s D-Bus and Varlink service names/sockets. This is also | |
a6f44d61 | 421 | understood by `homectl`. This too is useful for running an additional copy of |
67302b38 LP |
422 | `systemd-homed` that doesn't interfere with the host's main one. |
423 | ||
424 | * `$SYSTEMD_HOMEWORK_PATH` – configures the path to the `systemd-homework` | |
425 | binary to invoke. If not specified defaults to | |
426 | `/usr/lib/systemd/systemd-homework`. | |
427 | ||
428 | Combining these four environment variables is pretty useful when | |
429 | debugging/developing `systemd-homed`: | |
430 | ```sh | |
431 | SYSTEMD_HOME_DEBUG_SUFFIX=foo \ | |
432 | SYSTEMD_HOMEWORK_PATH=/home/lennart/projects/systemd/build/systemd-homework \ | |
433 | SYSTEMD_HOME_ROOT=/home.foo/ \ | |
434 | SYSTEMD_HOME_RECORD_DIR=/var/lib/systemd/home.foo/ \ | |
435 | /home/lennart/projects/systemd/build/systemd-homed | |
436 | ``` | |
db42f011 LP |
437 | |
438 | * `$SYSTEMD_HOME_MOUNT_OPTIONS_BTRFS`, `$SYSTEMD_HOME_MOUNT_OPTIONS_EXT4`, | |
439 | `$SYSTEMD_HOME_MOUNT_OPTIONS_XFS` – configure the default mount options to | |
440 | use for LUKS home directories, overriding the built-in default mount | |
441 | options. There's one variable for each of the supported file systems for the | |
442 | LUKS home directory backend. | |
a2a9d541 DDM |
443 | |
444 | `kernel-install`: | |
445 | ||
446 | * `$KERNEL_INSTALL_BYPASS` – If set to "1", execution of kernel-install is skipped | |
447 | when kernel-install is invoked. This can be useful if kernel-install is invoked | |
448 | unconditionally as a child process by another tool, such as package managers | |
449 | running kernel-install in a postinstall script. |