X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=man%2Fsystemd.xml;h=fc4810767ad1b301591c070e2c928f32de6f7cbe;hp=007705e4943ebaa296505c8e2195d2834be4747c;hb=8112e84f657839a056afb411249a627956518b24;hpb=99ffae46d38f05b6c8bc09fe29e50a507ae8b79b diff --git a/man/systemd.xml b/man/systemd.xml index 007705e49..fc4810767 100644 --- a/man/systemd.xml +++ b/man/systemd.xml @@ -45,7 +45,7 @@ systemd init - systemd System and Session Manager + systemd System and Service Manager @@ -60,7 +60,7 @@ Description - systemd is a system and session manager for + systemd is a system and service manager for Linux operating systems. When run as first process on boot (as PID 1), it acts as init system that brings up and maintains userspace services. @@ -73,6 +73,13 @@ are mostly equivalent when invoked from normal login sessions. See telinit8 for more information. + + When run as system instance, systemd interprets + the configuration file + system.conf, otherwise + user.conf. See + systemd.conf5 + for more information. @@ -88,28 +95,6 @@ Prints a short help text and exits. - - - - Set default unit to - activate on startup. If not specified - defaults to - default.target. - - - - - Tell systemd to run in - a particular mode. Argument is one of - , - . Normally it - should not be necessary to pass this - option, as systemd automatically - detects the mode it is started - in. This call is hence of little use - except for - debugging. - @@ -127,17 +112,12 @@ configuration items understood in unit definition files. - - - - Ask for confirmation when spawning processes. - Extract D-Bus interface introspection data. This is - mostly useful at build at install time + mostly useful at install time to generate data suitable for the D-Bus interfaces repository. Optionally the interface @@ -146,6 +126,94 @@ introspection data for all interfaces is dumped. + + + + Set default unit to + activate on startup. If not specified + defaults to + default.target. + + + + + + Tell systemd to run a + system instance (resp. user + instance), even if the process ID is + not 1 (resp. is 1), i.e. systemd is + not (resp. is) run as init process. + Normally it should not be necessary to + pass these options, as systemd + automatically detects the mode it is + started in. These options are hence of + little use except for debugging. Note + that it is not supported booting and + maintaining a full system with systemd + running in + mode, but PID not 1. In practice, + passing explicitly is + only useful in conjunction with + . + + + + + Dump core on + crash. This switch has no effect when + run as user + instance. + + + + + Run shell on + crash. This switch has no effect when + run as user + instance. + + + + + Ask for confirmation + when spawning processes. This switch + has no effect when run as user + instance. + + + + + Show terse service + status information while booting. This + switch has no effect when run as user + instance. Takes a boolean argument + which may be omitted which is + interpreted as + . + + + + + Controls whether + output of SysV init scripts will be + directed to the console. This switch + has no effect when run as user + instance. Takes a boolean argument + which may be omitted which is + interpreted as + . + + + + + Set log + target. Argument must be one of + , + , + , + , + . + @@ -162,17 +230,6 @@ , . - - - - Set log - target. Argument must be one of - , - , - , - , - . - @@ -193,6 +250,29 @@ it defaults to . + + + + + Sets the default + output resp. error output for all + services and sockets, i.e. controls + the default for + + resp. + (see + systemd.exec5 + for details). Takes one of + , + , + , + , + , + , + . If the + argument is omitted it defaults to + . + @@ -202,18 +282,29 @@ systemd provides a dependency system between various entities called "units". Units encapsulate various objects that are relevant for system boot-up - and maintainance. The majority of units are configured + and maintenance. The majority of units are configured in unit configuration files, whose syntax and basic set of options is described in systemd.unit5, however some are created automatically from other configuration or dynamically from system state. Units - may be active (meaning started, bound, plugged in, ... - depending on the unit type), or inactive (meaning - stopped, unbound, unplugged, ...), as well is in the - process of being activated or deactivated, - i.e. between the two states. The following unit types - are available: + may be 'active' (meaning started, bound, plugged in, + ... depending on the unit type, see below), or + 'inactive' (meaning stopped, unbound, unplugged, ...), + as well as in the process of being activated or + deactivated, i.e. between the two states (these states + are called 'activating', 'deactivating'). A special + 'failed' state is available as well which is very + similar to 'inactive' and is entered when the service + failed in some way (process returned error code on + exit, or crashed, or an operation timed out). If this + state is entered the cause will be logged, for later + reference. Note that the various unit types may have a + number of additional substates, which are mapped to + the five generalized unit states described + here. + + The following unit types are available: Service units, which control @@ -256,7 +347,7 @@ systemd units, which later may be restored by activating the saved snapshot unit. For more information see - systemd.automount5. + systemd.snapshot5. Timer units are useful for triggering activation of other units based on @@ -264,12 +355,12 @@ systemd.timer5. Swap units are very similar to - mount units and encapsulated memory swap + mount units and encapsulate memory swap partitions or files of the operating - systemd. They are described in systemd.swap5. + system. They are described in systemd.swap5. Path units may be used - activate other services when file system + to activate other services when file system objects change or are modified. See systemd.path5. @@ -277,11 +368,40 @@ Units are named as their configuration files. Some units have special semantics. A detailed - list you may find in + list is available in systemd.special7. + systemd knows various kinds of dependencies, + including positive and negative requirement + dependencies (i.e. Requires= and + Conflicts=) as well as ordering + dependencies (After= and + Before=). NB: ordering and + requirement dependencies are orthogonal. If only a + requirement dependency exists between two units + (e.g. foo.service requires + bar.service), but no ordering + dependency (e.g. foo.service + after bar.service) and both are + requested to start, they will be started in + parallel. It is a common pattern that both requirement + and ordering dependencies are placed between two + units. Also note that the majority of dependencies are + implicitly created and maintained by systemd. In most + cases it should be unnecessary to declare additional + dependencies manually, however it is possible to do + this. + + Application programs and units (via + dependencies) may request state changes of units. In + systemd, these requests are encapsulated as 'jobs' and + maintained in a job queue. Jobs may succeed or can + fail, their execution is ordered based on the ordering + dependencies of the units they have been scheduled + for. + On boot systemd activates the target unit - default.target whose job it is to + default.target whose job is to activate on-boot services and other on-boot units by pulling them in via dependencies. Usually the unit name is just an alias (symlink) for either @@ -296,10 +416,73 @@ systemd.special7 for details about these target units. + Processes systemd spawns are placed in + individual Linux control groups named after the unit + which they belong to in the private systemd + hierarchy. (see cgroups.txt + for more information about control groups, or short + "cgroups"). systemd uses this to effectively keep + track of processes. Control group information is + maintained in the kernel, and is accessible via the + file system hierarchy (beneath + /sys/fs/cgroup/systemd/), or in tools + such as + ps1 + (ps xawf -eo pid,user,cgroup,args + is particularly useful to list all processes and the + systemd units they belong to.). + + systemd is compatible with the SysV init system + to a large degree: SysV init scripts are supported and + simply read as an alternative (though limited) + configuration file format. The SysV + /dev/initctl interface is + provided, and compatibility implementations of the + various SysV client tools are available. In addition to + that, various established Unix functionality such as + /etc/fstab or the + utmp database are + supported. + + systemd has a minimal transaction system: if a + unit is requested to start up or shut down it will add + it and all its dependencies to a temporary + transaction. Then, it will verify if the transaction + is consistent (i.e. whether the ordering of all units + is cycle-free). If it is not, systemd will try to fix + it up, and removes non-essential jobs from the + transaction that might remove the loop. Also, systemd + tries to suppress non-essential jobs in the + transaction that would stop a running service. Finally + it is checked whether the jobs of the transaction + contradict jobs that have already been queued, and + optionally the transaction is aborted then. If all + worked out and the transaction is consistent and + minimized in its impact it is merged with all already + outstanding jobs and added to the run + queue. Effectively this means that before executing a + requested operation, systemd will verify that it makes + sense, fixing it if possible, and only failing if it + really cannot work. + + Systemd contains native implementations of + various tasks that need to be executed as part of the + boot process. For example, it sets the host name or + configures the loopback network device. It also sets + up and mounts various API file systems, such as + /sys or + /proc. + For more information about the concepts and ideas behind systemd please refer to the Original - Announcement Document. + Design Document. + + Note that some but not all interfaces provided + by systemd are covered by the Interface + Stability Promise. @@ -317,28 +500,31 @@ pkg-config systemd --variable=systemdsystemunitdir. Other directories checked are - /usr/local/share/systemd/system + /usr/local/lib/systemd/system and - /usr/share/systemd/system. User + /usr/lib/systemd/system. User configuration always takes precedence. pkg-config systemd --variable=systemdsystemconfdir returns the path of the system configuration directory. Packages - should alter the content of these directories - only with the - systemd-install1 + should alter the content of these + directories only with the + enable and + disable commands of + the + systemctl1 tool. - Session unit directories + User unit directories Similar rules apply - for the session unit + for the user unit directories. However, here the XDG Base Directory specification @@ -346,12 +532,15 @@ units. Applications should place their unit files in the directory returned by pkg-config systemd - --variable=systemdsessionunitdir. Global - configuration is done in the - directory reported by - pkg-config systemd - --variable=systemdsessionconfdir. The - systemd-install1 + --variable=systemduserunitdir. Global + configuration is done in the directory + reported by pkg-config + systemd + --variable=systemduserconfdir. The + enable and + disable commands of + the + systemctl1 tool can handle both global (i.e. for all users) and private (for one user) enabling/disabling of @@ -386,7 +575,7 @@ when figuring out whether a service shall be enabled. Note that a service unit with a native unit configuration - file can be started by activating it + file cannot be started by activating it in the SysV runlevel link farm. @@ -408,12 +597,12 @@ to systemctl daemon-reexec. - systemd session managers will + systemd user managers will start the exit.target unit when this signal is received. This is mostly equivalent to - systemctl --session start + systemctl --user start exit.target. @@ -428,7 +617,7 @@ systemctl start ctl-alt-del.target. - systemd session managers + systemd user managers treat this signal the same way as SIGTERM. @@ -445,7 +634,7 @@ kbrequest.target. This signal is ignored by - systemd session + systemd user managers. @@ -554,6 +743,101 @@ systemctl start reboot.target. + + + SIGRTMIN+6 + + Reboots the machine via kexec, + starts the + kexec.target + unit. This is mostly equivalent to + systemctl start + kexec.target. + + + + SIGRTMIN+13 + + Immediately halts the machine. + + + + SIGRTMIN+14 + + Immediately powers off the machine. + + + + SIGRTMIN+15 + + Immediately reboots the machine. + + + + SIGRTMIN+16 + + Immediately reboots the machine with kexec. + + + + SIGRTMIN+20 + + Enables display of + status messages on the console, as + controlled via + systemd.show_status=1 + on the kernel command + line. + + + + SIGRTMIN+21 + + Disables display of + status messages on the console, as + controlled via + systemd.show_status=0 + on the kernel command + line. + + + + SIGRTMIN+22 + SIGRTMIN+23 + + Sets the log level to + debug + (resp. info on + SIGRTMIN+32), as + controlled via + systemd.log_level=debug + (resp. systemd.log_level=info + on SIGRTMIN+23) on + the kernel command + line. + + + + SIGRTMIN+27 + SIGRTMIN+28 + SIGRTMIN+29 + + Sets the log level to + console + (resp. kmsg on + SIGRTMIN+28; + resp. syslog-or-kmsg + on SIGRTMIN+29), as + controlled via + systemd.log_target=console + (resp. systemd.log_target=kmsg + on SIGRTMIN+28; + resp + systemd.log_target=syslog-or-kmsg + on SIGRTMIN+29) on + the kernel command + line. + @@ -600,7 +884,7 @@ $XDG_DATA_HOME $XDG_DATA_DIRS - The systemd session + The systemd user manager uses these variables in accordance to the XDG @@ -656,25 +940,141 @@ + + Kernel Command Line + + When run as system instance systemd parses a few kernel command line arguments: + + + + systemd.unit= + + Overrides the unit to + activate on boot. Defaults to + default.target. This + may be used to temporarily boot into a + different boot unit, for example + rescue.target or + emergency.service. See + systemd.special7 + for details about these + units. + + + + systemd.dump_core= + + Takes a boolean + argument. If + systemd dumps core when it + crashes. Otherwise no core dump is + created. Defaults to + . + + + + systemd.crash_shell= + + Takes a boolean + argument. If + systemd spawns a shell when it + crashes. Otherwise no shell is + spawned. Defaults to + , for security + reasons, as the shell is not protected + by any password + authentication. + + + + systemd.crash_chvt= + + Takes an integer + argument. If positive systemd + activates the specified virtual + terminal when it crashes. Defaults to + -1. + + + + systemd.confirm_spawn= + + Takes a boolean + argument. If + asks for confirmation when spawning + processes. Defaults to + . + + + + systemd.show_status= + + Takes a boolean + argument. If + shows terse service status updates on + the console during bootup. Defaults to + . + + + + systemd.sysv_console= + + Takes a boolean + argument. If + output of SysV init scripts will be + directed to the console. Defaults to + , unless + is passed as + kernel command line option in which + case it defaults to + . + + + + systemd.log_target= + systemd.log_level= + systemd.log_color= + systemd.log_location= + + Controls log output, + with the same effect as the + $SYSTEMD_LOG_TARGET, $SYSTEMD_LOG_LEVEL, $SYSTEMD_LOG_COLOR, $SYSTEMD_LOG_LOCATION + environment variables described above. + + + + systemd.default_standard_output= + systemd.default_standard_error= + Controls default + standard output/error output for + services, with the same effect as the + + resp. + command line arguments described + above. + + + + + Sockets and FIFOs - @/org/freedesktop/systemd1/notify + /run/systemd/notify Daemon status - notification socket. This is an AF_UNIX - datagram socket in the Linux abstract - namespace, and is used to implement - the daemon notification logic as - implemented by + notification socket. This is an + AF_UNIX datagram socket and is used to + implement the daemon notification + logic as implemented by sd_notify3. - @/org/freedesktop/systemd1/logger + /run/systemd/logger Used internally by the systemd-logger.service @@ -682,21 +1082,30 @@ of spawned processes to syslog3 or the kernel log buffer. This is an - AF_UNIX stream socket in the Linux - abstract namespace. + AF_UNIX stream + socket. + + + + /run/systemd/shutdownd + + Used internally by the + shutdown8 + tool to implement delayed + shutdowns. This is an AF_UNIX datagram + socket. - @/org/freedesktop/systemd1/private + /run/systemd/private Used internally as communication channel between systemctl1 and the systemd process. This is an - AF_UNIX stream socket in the Linux - abstract namespace. This interface is - private to systemd and should not be - used in external + AF_UNIX stream socket. This interface + is private to systemd and should not + be used in external projects. @@ -720,7 +1129,6 @@ systemctl1, systemadm1, - systemd-install1, systemd-notify1, daemon7, sd-daemon7,