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Joachim Wiberg
4299ce8839
The migration guide covered a stanza at a time, which is the wrong
shape for the two idioms that repeated a whole stanza. One of them,
several candidate binaries for one service, is now a command list.
The other, one service gated differently per platform, has no block
equivalent: those blocks share an identity because they share the
barrier condition downstream services wait for, so they cannot be
given separate titles. For that one the guide says to split the
variants across files, or leave that file in the line-based format,
which Finit still reads.
The udevd example in services.md taught the merge-broken form, and
system/10-hotplug.conf.in pointed readers at it for their syslogd.
Also lists libConfuse among the build dependencies. It has been
mandatory since the new .conf format landed, and build.md still said
two libraries. And corrects the note on variable expansion: it is
${VAR} that libconfuse expands when the file is read, with
${VAR:-default} supported. A plain $VAR reaches the service, which is
what makes `command = "syslogd -F $SYSLOGD_ARGS"` work with envfile.
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>
241 lines
11 KiB
Markdown
241 lines
11 KiB
Markdown
Syntax Migration Guide
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======================
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Finit reads both configuration formats. Every file is still `*.conf`,
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and the format is detected per file, so a system can be migrated one
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file at a time -- a file is one format or the other, never a mix.
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This guide maps each part of a line-based stanza to its block key.
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The shape of the change:
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service [S12345] <pid/syslogd> env:-/etc/default/klogd name:klogd klogd -n $KLOGD_OPTS -- Kernel log daemon
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becomes
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service klogd {
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description = "Kernel log daemon"
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runlevel = "S12345"
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conditions = { "pid/syslogd" }
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envfile = "-/etc/default/klogd"
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command = "klogd -n $KLOGD_OPTS"
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}
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The block title is the service identity, shown by `initctl`. Multiple
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instances spell the ID in the title: `service sshd:1 { ... }`. The
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legacy bare-ID form, `service :80 ...`, has no equivalent -- the title
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carries both name and ID.
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Positional parts
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----------------
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| Line-based | Block key |
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|----------------------------------|-------------------------------------------------------|
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| `service`, `task`, `run`, `sysv` | same, as block type |
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| `[S12345]` | `runlevel = "S12345"` |
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| `<pid/a,net/b>` | `conditions = { "pid/a", "net/b" }` |
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| `<!pid/a>` on service/sysv | `conditions = { "pid/a" }` + `reload-signal = "none"` |
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| `<!pid/a>` on run/task | `conditions = { "pid/a" }` + `required = false` |
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| `@user:group,extra` | `user`, `group`, `extra-groups = { "extra" }` |
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| `name:foo :1` | block title `foo:1` |
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| the command and arguments | `command = "..."` |
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| `-- Description text` | `description = "..."` |
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The `!` was a flag on the stanza, not a negation, and meant different
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things for daemons and one-shots; each meaning is now its own key. A
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`~` prefix on a condition is unchanged: `conditions = { "~pid/a" }`.
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Service options
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---------------
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| Line-based | Block key |
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|----------------------------------|--------------------------------------------------|
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| `env:[-]/path` | `envfile = "[-]/path"` |
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| `pid:/path` | `pidfile = "/path"` + `pidfile-create = true` |
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| `pid:!/path` | `pidfile = "/path"` |
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| `pid` | `pidfile = true` + `pidfile-create = true` |
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| `log` | `log { }` |
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| `log:/path` | `log { file = "/path" }` |
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| `log:null`, `log:console` | `log { file = "/dev/null" }`, `"/dev/console"` |
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| `log:prio:p,tag:t` | `log { priority = "p" identity = "t" }` |
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| `notify:systemd` | `notify = "systemd"` |
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| `type:forking` | `type = "forking"` |
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| `manual:yes` | `manual-start = true` |
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| `remain:yes` | `remain-after-exit = true` |
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| `restart:always` / `restart:NUM` | `restart = "always"` / `restart-max = NUM` |
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| `restart_sec:SEC` | `restart-sec = SEC` |
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| `norestart` | `restart = "never"` |
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| `respawn` | `respawn = true` |
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| `oncrash:reboot` | `oncrash = "reboot"` |
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| `halt:SIG` | `stop-signal = "SIG"` |
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| `kill:SEC` | `stop-timeout = SEC` |
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| `pre:[TMO,]/script` | `exec-start-pre`, `exec-start-pre-timeout` |
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| `ready:[TMO,]/script` | `exec-start-ready`, and its `-timeout` |
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| `stop:[TMO,]/script` | `exec-stop`, and its `-timeout` |
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| `post:[TMO,]/script` | `exec-stop-post`, and its `-timeout` |
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| `reload:[TMO,]/script` | `exec-reload`, and its `-timeout` |
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| `cleanup:[TMO,]/script` | `exec-cleanup`, and its `-timeout` |
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| `caps:^cap_a,%cap_b` | `capabilities = { "^cap_a", "%cap_b" }` |
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| `conflict:a,b` | `conflicts = { "a", "b" }` |
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| `if:svc` / `if:<cond>` | `if = "svc"` / `if = "cond"`, no angle brackets |
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| `tty:/dev/x` | `tty = "/dev/x"` |
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| `nowarn` | leading `-` on `command` or `envfile` |
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| `restarttmo:` | dropped, was already an alias for `restart_sec:` |
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Repeated stanzas
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----------------
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The line-based format has no titles, so the same service could be
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declared more than once and Finit would sort out which line applied.
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A block title *is* the identity, and two blocks sharing one in the
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same file are rejected. The two shapes that relied on the repetition
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convert differently.
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**Several candidate binaries for one service.** The daemon is known
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under more than one name and the stanzas were repeated once per name,
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each with `nowarn` so the ones that were not installed were skipped:
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service nowarn pid:!/run/udevd.pid [S12345789] /lib/systemd/systemd-udevd -- Device event daemon
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service nowarn pid:!/run/udevd.pid [S12345789] udevd -- Device event daemon
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The candidates now go in one block, and Finit starts the first one it
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finds:
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service udevd {
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description = "Device event daemon"
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runlevel = "S12345789"
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pidfile = "/run/udevd.pid"
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command = { "/lib/systemd/systemd-udevd", "-udevd" }
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}
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**One service gated differently per platform.** The command is the
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same every time, only `if:` and the conditions differ, e.g. a syslog
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daemon that has to wait for whichever hotplug daemon the system has:
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service if:udevd nowarn env:-/etc/default/sysklogd <run/udevadm:5/success> \
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[S0123456789] syslogd -F $SYSLOGD_ARGS -- System log daemon
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service if:mdev nowarn env:-/etc/default/sysklogd <run/coldplug/success> \
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[S0123456789] syslogd -F $SYSLOGD_ARGS -- System log daemon
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All of these are one service, `syslogd`, providing one `pid/syslogd`
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barrier for everything downstream, so they cannot be given separate
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titles without renaming that barrier. There are two ways to keep the
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identity:
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* put each variant in its own .conf file, since the ban on duplicate
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titles is per file, or
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* leave this one file in the line-based format, which Finit still
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reads. Format is detected per file, so the rest of the system can
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be block format.
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A single variant converts the way anything else does:
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service syslogd {
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description = "System log daemon"
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runlevel = "S0123456789"
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if = "udevd"
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conditions = { "run/udevadm:5/success" }
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envfile = "-/etc/default/sysklogd"
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command = "-syslogd -F $SYSLOGD_ARGS"
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}
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Cgroups
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-------
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The standalone `cgroup.NAME` line selected a group for every stanza
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after it in the file, and `cgroup:opts` applied settings to whichever
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group was current. Neither survives: every block names its own group,
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so nothing depends on what came earlier in the file.
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cgroup.maint
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service [2345] cgroup:cpu.weight:250 foo -- Foo daemon
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becomes
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service foo {
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description = "Foo daemon"
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runlevel = "2345"
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cgroup maint { cpu.weight = 250 }
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command = "foo"
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}
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Top-level group declarations keep their name and settings:
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cgroup system cpu.weight:9700 mem.max:10M
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becomes
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cgroup system {
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cpu.weight = 9700
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memory.max = 10M
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}
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TTYs
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----
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The three positional variants become three key choices:
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tty [12345] /dev/ttyS0 115200 noclear vt220
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tty [12345] /sbin/getty -L ttyS0 115200 vt100
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tty [12345] notty
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become
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tty ttyS0 {
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runlevel = "12345"
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device = "/dev/ttyS0"
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baud = 115200
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term = "vt220"
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noclear = true
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}
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tty getty {
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runlevel = "12345"
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command = "/sbin/getty -L ttyS0 115200 vt100"
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}
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tty shell {
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runlevel = "12345"
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notty = true
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}
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Top-level directives
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--------------------
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| Line-based | Block key |
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|----------------------------------|----------------------------------------------------------|
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| `host NAME`, `hostname NAME` | `hostname = "NAME"` |
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| `module foo args` (repeated) | `modules = { "foo args", ... }` |
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| `network script args` | `network = "script args"` |
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| `runlevel N` | `runlevel = N` |
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| `rcsd /path` | `rcsd = "/path"` |
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| `runparts [progress] [sysv] DIR` | `runparts = "DIR"`, `runparts-progress`, `runparts-sysv` |
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| `set KEY=VAL` (repeated) | `environment { KEY = "VAL" }` |
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| `log size:100k count:4` | `log { size = 100k count = 4 }` |
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| `rlimit [hard\|soft] RES LIM` | `rlimit { hard.res = LIM }` |
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| `readiness none` | `readiness = "none"` |
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| `reboot-delay N` | `reboot-delay = N` |
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| `reboot-watchdog on` | `reboot-watchdog = true` |
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| `service-interval SEC` | `service-interval = SEC` |
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| `shutdown script` | `shutdown = "script"` |
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| `mknod /dev/x c 1 2` | `mknod = { "/dev/x c 1 2" }` |
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| `include /path` | `include("/path")` |
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Worth knowing
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-------------
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* Templates work unchanged: `%i` is replaced before the file is
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parsed, so `service serv:%i { ... }` in a `serv@.conf` behaves
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exactly like its legacy counterpart.
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* A list cannot hold comments; the lexer reads entries after a `#`
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regardless. Put commented-out candidates above the list.
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* `${VAR}` in a value is expanded when the file is read, against
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Finit's environment, and `${VAR:-default}` works too. An unset
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variable expands to nothing. A plain `$VAR` is left alone and
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reaches the service, which is what keeps `command = "syslogd -F
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$SYSLOGD_ARGS"` working with an `envfile`.
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* New settings only appear in the block format. The first are the
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[per-service directories](service-opts.md#service-directories),
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`runtime-dir` and friends.
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For the full description of every key, see the rest of the
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[Configuration](index.md) section.
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