X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=blobdiff_plain;f=man%2Fsystemd.xml;h=6edce4996a99ba76cb5f6bc03c70436954518d41;hp=36bce961854705331e4383b7b77fc4b1b5fcc848;hb=20d910092d61dff9ae4e2500efd26ec68ca208b2;hpb=7874bcd6028d1efbb4451c8b5cf5b2ac8d77af74 diff --git a/man/systemd.xml b/man/systemd.xml index 36bce9618..6edce4996 100644 --- a/man/systemd.xml +++ b/man/systemd.xml @@ -44,6 +44,7 @@ systemd + init systemd System and Session Manager @@ -61,17 +62,24 @@ systemd is a system and session manager for Linux operating systems. When run as first process on - boot (as PID 1) it may act as init system that brings - up and maintains userspace. + boot (as PID 1), it acts as init system that brings + up and maintains userspace services. - For compatibility with SysV if systemd is called + For compatibility with SysV, if systemd is called as init and a PID that is not - 1 it will execute telinit and pass + 1, it will execute telinit and pass all command line arguments unmodified. That means init and telinit 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 + session.conf. See + systemd.conf5 + for more information. @@ -87,28 +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. - @@ -126,25 +112,93 @@ 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 ot install time + mostly useful at install time to generate data suitable for the D-Bus interfaces repository. Optionally the interface name for the introspection data may be - specified. If omitted the + specified. If omitted, the 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. session + 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. + + + + + Dump core on crash. This switch has no effect when run as session instance. + + + + + Run shell on crash. This switch has no effect when run as session instance. + + + + + Ask for confirmation when spawning processes. This switch has no effect when run as session instance. + + + + + Show terse service + status information while booting. This + switch has no effect when run as + session 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 session + instance. Takes a boolean argument + which may be omitted which is + interpreted as + . + + + + + Set log + target. Argument must be one of + , + , + , + , + . + @@ -161,17 +215,6 @@ , . - - - - Set log - target. Argument must be one of - , - , - , - , - . - @@ -195,6 +238,210 @@ + + Concepts + + systemd provides a dependency system between + various entities called "units". Units encapsulate + various objects that are relevant for system boot-up + 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, 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 + 'maintenance' 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 + daemons and the processes they consist of. For + details see + systemd.service5. + + Socket units, which + encapsulate local IPC or network sockets in + the system, useful for socket-based + activation. For details about socket units see + systemd.socket5, + for details on socket-based activation and + other forms of activation, see + daemon7. + + Target units are useful to + group units, or provide well-known + synchronization points during boot-up, see + systemd.target5. + + Device units expose kernel + devices in systemd and may be used to + implement device-based activation. For details + see + systemd.device5. + + Mount units control mount + points in the file system, for details see + systemd.mount5. + + Automount units provide + automount capabilities, for on-demand mounting + of file systems as well as parallelized + boot-up. See + systemd.automount5. + + Snapshot units can be used to + temporarily save the state of the set of + systemd units, which later may be restored by + activating the saved snapshot unit. For more + information see + systemd.snapshot5. + + Timer units are useful for + triggering activation of other units based on + timers. You may find details in + systemd.timer5. + + Swap units are very similar to + mount units and encapsulated memory swap + partitions or files of the operating + systemd. They are described in systemd.swap5. + + Path units may be used + to activate other services when file system + objects change or are modified. See + systemd.path5. + + + + Units are named as their configuration + files. Some units have special semantics. A detailed + list you may find 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 requests 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 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 + graphical.target (for + fully-featured boots into the UI) or + multi-user.target (for limited + console-only boots for use in embedded or server + environments, or similar; a subset of + graphical.target). However it is at the discretion of + the administrator to configure it as an alias to any + other target unit. See + 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 + /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 + Design Document. + + Directories @@ -219,9 +466,12 @@ --variable=systemdsystemconfdir returns the path of the system configuration directory. Packages - should alter this directory only with + should alter the content of these + directories only with the + enable and + disable commands of the - systemd-install1 + systemctl1 tool. @@ -240,11 +490,14 @@ unit files in the directory returned by pkg-config systemd --variable=systemdsessionunitdir. Global - configuration is done in the - directory reported by - pkg-config systemd + configuration is done in the directory + reported by pkg-config + systemd --variable=systemdsessionconfdir. The - systemd-install1 + 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 @@ -260,7 +513,7 @@ SysV init script directory varies between distributions. If systemd cannot find a native unit file for a - requested service it will look for a + requested service, it will look for a SysV init script of the same name (with the .service suffix @@ -279,7 +532,7 @@ 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. @@ -458,7 +711,7 @@ $SYSTEMD_LOG_LEVEL systemd reads the log level from this environment - variable. This can be overriden with + variable. This can be overridden with . @@ -466,7 +719,7 @@ $SYSTEMD_LOG_TARGET systemd reads the log target from this environment - variable. This can be overriden with + variable. This can be overridden with . @@ -474,7 +727,7 @@ $SYSTEMD_LOG_COLOR Controls whether systemd highlights important log - messages. This can be overriden with + messages. This can be overridden with . @@ -483,7 +736,7 @@ Controls whether systemd prints the code location along with log messages. This can be - overriden with + overridden with . @@ -549,6 +802,111 @@ + + 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 core dump is + created. 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. + + + + + Sockets and FIFOs @@ -579,6 +937,17 @@ abstract namespace. + + @/org/freedesktop/systemd1/shutdown + + Used internally by the + shutdown8 + tool to implement delayed + shutdowns. This is an AF_UNIX datagram + socket in the Linux abstract + namespace. + + @/org/freedesktop/systemd1/private @@ -613,7 +982,6 @@ systemctl1, systemadm1, - systemd-install1, systemd-notify1, daemon7, sd-daemon7,