os_mon

v2.11.2

cpu_sup

A CPU Load and CPU Utilization Supervisor Process

cpu_sup is a process which supervises the CPU load and CPU utilization. It is part of the OS_Mon application, see os_mon(6). Available for Unix, although CPU utilization values (util/0,1) are only available for Solaris, Linux, FreeBSD and OpenBSD.

The load values are proportional to how long time a runnable Unix process has to spend in the run queue before it is scheduled. Accordingly, higher values mean more system load. The returned value divided by 256 produces the figure displayed by rup and top. What is displayed as 2.00 in rup, is displayed as load up to the second mark in xload.

For example, rup displays a load of 128 as 0.50, and 512 as 2.00.

If the user wants to view load values as percentage of machine capacity, then this way of measuring presents a problem, because the load values are not restricted to a fixed interval. In this case, the following simple mathematical transformation can produce the load value as a percentage:

PercentLoad = 100 * (1 - D/(D + Load))

D determines which load value should be associated with which percentage. Choosing D = 50 means that 128 is 60% load, 256 is 80%, 512 is 90%, and so on.

Another way of measuring system load is to divide the number of busy CPU cycles by the total number of CPU cycles. This produces values in the 0-100 range immediately. However, this method hides the fact that a machine can be more or less saturated. CPU utilization is therefore a better name than system load for this measure.

A server which receives just enough requests to never become idle will score a CPU utilization of 100%. If the server receives 50% more requests, it will still score 100%. When the system load is calculated with the percentage formula shown previously, the load will increase from 80% to 87%.

The avg1/0, avg5/0, and avg15/0 functions can be used for retrieving system load values, and the util/0 and util/1 functions can be used for retrieving CPU utilization values.

When run on Linux, cpu_sup assumes that the /proc file system is present and accessible by cpu_sup. If it is not, cpu_sup will terminate.

See Also

os_mon(3)

Summary

Types

util_cpus()

util_desc()

util_state()

util_value()

Functions

avg1()

Returns the average system load in the last minute, as described above. 0 represents no load, 256 represents the load reported as 1.00 by rup.

avg5()

Returns the average system load in the last five minutes, as described above. 0 represents no load, 256 represents the load reported as 1.00 by rup.

avg15()

Returns the average system load in the last 15 minutes, as described above. 0 represents no load, 256 represents the load reported as 1.00 by rup.

nprocs()

Returns the number of UNIX processes running on this machine. This is a crude way of measuring the system load, but it may be of interest in some cases.

util()

Returns CPU utilization since the last call to util/0 or util/1 by the calling process.

util/1

Returns CPU utilization since the last call to util/0 or util/1 by the calling process, in more detail than util/0.

Types

util_cpus()

(not exported)

-type util_cpus() :: all | integer() | [integer()].

util_desc()

(not exported)

-type util_desc() :: {util_cpus(), util_value(), util_value(), []}.

util_state()

(not exported)

-type util_state() :: user | nice_user | kernel | wait | idle.

util_value()

(not exported)

-type util_value() :: [{util_state(), number()}] | number().

Functions

avg1()

-spec avg1() -> SystemLoad :: integer() | {error, any()}.

Returns the average system load in the last minute, as described above. 0 represents no load, 256 represents the load reported as 1.00 by rup.

Returns 0 if cpu_sup is not available.

avg5()

-spec avg5() -> SystemLoad :: integer() | {error, any()}.

Returns the average system load in the last five minutes, as described above. 0 represents no load, 256 represents the load reported as 1.00 by rup.

Returns 0 if cpu_sup is not available.

avg15()

-spec avg15() -> SystemLoad :: integer() | {error, any()}.

Returns the average system load in the last 15 minutes, as described above. 0 represents no load, 256 represents the load reported as 1.00 by rup.

Returns 0 if cpu_sup is not available.

nprocs()

-spec nprocs() -> UnixProcesses :: integer() | {error, any()}.

Returns the number of UNIX processes running on this machine. This is a crude way of measuring the system load, but it may be of interest in some cases.

Returns 0 if cpu_sup is not available.

util()

-spec util() -> CpuUtil :: number() | {error, any()}.

Returns CPU utilization since the last call to util/0 or util/1 by the calling process.

Note

The returned value of the first call to util/0 or util/1 by a process will on most systems be the CPU utilization since system boot, but this is not guaranteed and the value should therefore be regarded as garbage. This also applies to the first call after a restart of cpu_sup.

The CPU utilization is defined as the sum of the percentage shares of the CPU cycles spent in all busy processor states (see util/1) in average on all CPUs.

Returns 0 if cpu_sup is not available.

util/1

-spec util([detailed | per_cpu]) -> util_desc() | [util_desc()] | {error, any()}.

Returns CPU utilization since the last call to util/0 or util/1 by the calling process, in more detail than util/0.

Note

The returned value of the first call to util/0 or util/1 by a process will on most systems be the CPU utilization since system boot, but this is not guaranteed and the value should therefore be regarded as garbage. This also applies to the first call after a restart of cpu_sup.

Currently recognized options:

detailed - The returned UtilDesc(s) will be even more detailed.

per_cpu - Each CPU will be specified separately (assuming this information can be retrieved from the operating system), that is, a list with one UtilDesc per CPU will be returned.

Description of UtilDesc = {Cpus, Busy, NonBusy, Misc}:

Cpus - If the detailed and/or per_cpu option is given, this is the CPU number, or a list of the CPU numbers.

If not, this is the atom all which implies that the UtilDesc contains information about all CPUs.

Busy - If the detailed option is given, this is a list of {State, Share} tuples, where each tuple contains information about a processor state that has been identified as a busy processor state (see below). The atom State is the name of the state, and the float Share represents the percentage share of the CPU cycles spent in this state since the last call to util/0 or util/1.

If not, this is the sum of the percentage shares of the CPU cycles spent in all states identified as busy.

If the per_cpu is not given, the value(s) presented are the average of all CPUs.

NonBusy - Similar to Busy, but for processor states that have been identified as non-busy (see below).

Misc - Currently unused; reserved for future use.

Currently these processor states are identified as busy:

user - Executing code in user mode.

nice_user - Executing code in low priority (nice) user mode. This state is currently only identified on Linux.

kernel - Executing code in kernel mode.

Currently these processor states are identified as non-busy:

wait - Waiting. This state is currently only identified on Solaris.

idle - Idle.

Note

Identified processor states may be different on different operating systems and may change between different versions of cpu_sup on the same operating system. The sum of the percentage shares of the CPU cycles spent in all busy and all non-busy processor states will always add up to 100%, though.

Returns {all,0,0,[]} if cpu_sup is not available.

disksup

A Disk Supervisor Process

disksup is a process which supervises the available disk space in the system. It is part of the OS_Mon application, see os_mon(6). Available for Unix and Windows.

Periodically checks the disks. For each disk or partition which uses more than a certain amount of the available space, the alarm {{disk_almost_full, MountedOn}, []} is set.

On Unix - All (locally) mounted disks are checked, including the swap disk if it is present.

On WIN32 - All logical drives of type "FIXED_DISK" are checked.

Alarms are reported to the SASL alarm handler, see alarm_handler. To set an alarm, alarm_handler:set_alarm(Alarm) is called where Alarm is the alarm specified above.

The alarms are cleared automatically when the alarm cause is no longer valid.

Configuration

The following configuration parameters can be used to change the default values for time interval and threshold:

disk_space_check_interval = time/0 - The time interval for the periodic disk space check. The default is 30 minutes.

disk_almost_full_threshold = float() - The threshold, as percentage of total disk space, for how much disk can be utilized before the disk_almost_full alarm is set. The default is 0.80 (80%).

disksup_posix_only = bool() - Specifies whether the disksup helper process should only use POSIX conformant commands (true) or not. The default is false. Setting this parameter to true can be necessary on embedded systems with stripped-down versions of Unix tools like df. The returned disk data and alarms can be different when using this option.

The parameter is ignored on platforms that are known to not be POSIX compatible (Windows and SunOS).

See config for information about how to change the value of configuration parameters.

See Also

alarm_handler, os_mon

Summary

Types

time()

Time unit used for disklog APIs.

Functions

get_almost_full_threshold()

Returns the threshold, in percent, for disk space utilization.

get_check_interval()

Returns the time interval, in milliseconds, for the periodic disk space check.

get_disk_data()

Returns the result of the latest disk check.

get_disk_info()

Immediately fetches total space, available space and capacity for local disks.

get_disk_info(Path)

Immediately fetches total space, available space and capacity for a path.

set_almost_full_threshold(Float)

Changes the threshold, given as a float (0.0 =< Float =< 1.0), for disk space utilization.

set_check_interval(Value)

Changes the time interval for the periodic disk space check.

Types

time()

(not exported)

-type time() :: pos_integer() | {TimeUnit :: erlang:time_unit(), Time :: pos_integer()}.

Time unit used for disklog APIs.

Supported units are:

integer() >= 1 - The time interval in minutes.

{TimeUnit, Time} - The time interval Time in a time unit specified by TimeUnit where TimeUnit is of the type erlang:time_unit/0 and Time is a positive integer. The time interval needs to be at least one millisecond long.

Functions

get_almost_full_threshold()

-spec get_almost_full_threshold() -> Percent :: integer().

Returns the threshold, in percent, for disk space utilization.

get_check_interval()

-spec get_check_interval() -> Milliseconds :: timer:time().

Returns the time interval, in milliseconds, for the periodic disk space check.

get_disk_data()

-spec get_disk_data() -> [DiskData]
                       when
                           DiskData :: {Id, TotalKiB, Capacity},
                           Id :: string(),
                           TotalKiB :: integer(),
                           Capacity :: integer().

Returns the result of the latest disk check.

Id is a string that identifies the disk or partition. TotalKiB is the total size of the disk or partition in kibibytes. Capacity is the percentage of disk space used.

The function is asynchronous in the sense that it does not invoke a disk check, but returns the latest available value.

Returns [{"none",0,0}] if disksup is not available.

get_disk_info()

(since OTP 26.0)

-spec get_disk_info() -> [DiskData]
                       when
                           DiskData :: {Id, TotalKiB, AvailableKiB, Capacity},
                           Id :: string(),
                           TotalKiB :: integer(),
                           AvailableKiB :: integer(),
                           Capacity :: integer().

Immediately fetches total space, available space and capacity for local disks.

Id is a string that identifies the disk or partition. TotalKiB is the total size of the disk or partition in kibibytes. AvailableKiB is the disk space used in kibibytes. Capacity is the percentage of disk space used.

Returns [{"none",0,0,0}] if disksup is not available.

get_disk_info(Path)

(since OTP 26.0)

-spec get_disk_info(Path :: string()) -> [DiskData]
                       when
                           DiskData :: {Id, TotalKiB, AvailableKiB, Capacity},
                           Id :: string(),
                           TotalKiB :: integer(),
                           AvailableKiB :: integer(),
                           Capacity :: integer().

Immediately fetches total space, available space and capacity for a path.

Id is a string that identifies the disk or partition. TotalKiB is the total size of the disk or partition in kibibytes. AvailableKiB is the disk space used in kibibytes. Capacity is the percentage of disk space used.

Returns [{Path,0,0,0}] if the Path is invalid or space can't be determined. Returns [{"none",0,0,0}] if disksup is not available.

set_almost_full_threshold(Float)

-spec set_almost_full_threshold(Float :: float()) -> ok.

Changes the threshold, given as a float (0.0 =< Float =< 1.0), for disk space utilization.

The change will take effect during the next disk space check and is non-persist. That is, in case of a process restart, this value is forgotten and the default value will be used. See Configuration above.

set_check_interval(Value)

-spec set_check_interval(time()) -> ok.

Changes the time interval for the periodic disk space check.

The change will take effect after the next disk space check and is non-persist. That is, in case of a process restart, this value is forgotten and the default value will be used. See Configuration above.

memsup

A Memory Supervisor Process

memsup is a process which supervises the memory usage for the system and for individual processes. It is part of the OS_Mon application, see os_mon. Available for Unix and Windows.

Periodically performs a memory check:

If more than a certain amount of available system memory is allocated, as reported by the underlying operating system, the alarm {system_memory_high_watermark, []} is set. How the amount of available memory is determined depends on the underlying OS and may change as better values become available.

If any Erlang process Pid in the system has allocated more than a certain amount of total system memory, the alarm {process_memory_high_watermark, Pid} is set.

Alarms are reported to the SASL alarm handler, see alarm_handler. To set an alarm, alarm_handler:set_alarm(Alarm) is called where Alarm is either of the alarms specified above.

The alarms are cleared automatically when the alarm cause is no longer valid.

The function get_memory_data() can be used to retrieve the result of the latest periodic memory check.

There is also a interface to system dependent memory data, get_system_memory_data(). The result is highly dependent on the underlying operating system and the interface is targeted primarily for systems without virtual memory. However, the output on other systems is still valid, although sparse.

A call to get_system_memory_data/0 is more costly than a call to get_memory_data/0 as data is collected synchronously when this function is called.

The total system memory reported under UNIX is the number of physical pages of memory times the page size, and the available memory is the number of available physical pages times the page size. This is a reasonable measure as swapping should be avoided anyway, but the task of defining total memory and available memory is difficult because of virtual memory and swapping.

Configuration

The following configuration parameters can be used to change the default values for time intervals and thresholds:

memory_check_interval = int()>0 - The time interval, in minutes, for the periodic memory check. The default is one minute.

system_memory_high_watermark = float() - The threshold, as percentage of system memory, for how much system memory can be allocated before the corresponding alarm is set. The default is 0.80 (80%).

process_memory_high_watermark = float() - The threshold, as percentage of system memory, for how much system memory can be allocated by one Erlang process before the corresponding alarm is set. The default is 0.05 (5%).

memsup_helper_timeout = int()>0 - A timeout, in seconds, for how long the memsup process should wait for a result from a memory check. If the timeout expires, a warning message "OS_MON (memsup) timeout" is issued via error_logger and any pending, synchronous client calls will return a dummy value. Normally, this situation should not occur. There have been cases on Linux, however, where the pseudo file from which system data is read is temporarily unavailable when the system is heavily loaded.

The default is 30 seconds.

memsup_system_only = bool() - Specifies whether the memsup process should only check system memory usage (true) or not. The default is false, meaning that information regarding both system memory usage and Erlang process memory usage is collected.

It is recommended to set this parameter to true on systems with many concurrent processes, as each process memory check makes a traversal of the entire list of processes.

See config for information about how to change the value of configuration parameters.

See Also

alarm_handler, os_mon

Summary

Functions

get_check_interval()

Returns the time interval, in milliseconds, for the periodic memory check.

get_helper_timeout()

Returns the timeout value, in seconds, for memory checks.

get_memory_data()

Returns the result of the latest memory check, where Total is the total memory size and Allocated the allocated memory size, in bytes.

get_os_wordsize()

Returns the wordsize of the current running operating system.

get_procmem_high_watermark()

Returns the threshold, in percent, for process memory allocation.

get_sysmem_high_watermark()

Returns the threshold, in percent, for system memory allocation.

get_system_memory_data()

Invokes a memory check and returns the resulting, system dependent, data as a list of tagged tuples, where Tag currently can be one of the following

set_check_interval(Minutes)

Changes the time interval, given in minutes, for the periodic memory check.

set_helper_timeout(Seconds)

Changes the timeout value, given in seconds, for memory checks.

set_procmem_high_watermark(Float)

Changes the threshold, given as a float, for process memory allocation.

set_sysmem_high_watermark(Float)

Changes the threshold, given as a float, for system memory allocation.

Functions

get_check_interval()

-spec get_check_interval() -> Milliseconds :: timer:time().

Returns the time interval, in milliseconds, for the periodic memory check.

get_helper_timeout()

-spec get_helper_timeout() -> Seconds :: integer().

Returns the timeout value, in seconds, for memory checks.

get_memory_data()

-spec get_memory_data() -> {Total, Allocated, Worst}
                         when
                             Total :: integer(),
                             Allocated :: integer(),
                             Worst :: {Pid, PidAllocated} | undefined,
                             Pid :: pid(),
                             PidAllocated :: integer().

Returns the result of the latest memory check, where Total is the total memory size and Allocated the allocated memory size, in bytes.

Worst is the pid and number of allocated bytes of the largest Erlang process on the node. If memsup should not collect process data, that is if the configuration parameter memsup_system_only was set to true, Worst is undefined.

The function is normally asynchronous in the sense that it does not invoke a memory check, but returns the latest available value. The one exception if is the function is called before a first memory check is finished, in which case it does not return a value until the memory check is finished.

Returns {0,0,{pid(),0}} or {0,0,undefined} if memsup is not available, or if all memory checks so far have timed out.

get_os_wordsize()

-spec get_os_wordsize() -> Wordsize when Wordsize :: 32 | 64 | unsupported_os.

Returns the wordsize of the current running operating system.

get_procmem_high_watermark()

-spec get_procmem_high_watermark() -> integer().

Returns the threshold, in percent, for process memory allocation.

get_sysmem_high_watermark()

-spec get_sysmem_high_watermark() -> integer().

Returns the threshold, in percent, for system memory allocation.

get_system_memory_data()

-spec get_system_memory_data() -> MemDataList
                                when MemDataList :: [{Tag, Size}], Tag :: atom(), Size :: integer().

Invokes a memory check and returns the resulting, system dependent, data as a list of tagged tuples, where Tag currently can be one of the following:

total_memory - The total amount of memory available to the Erlang emulator, allocated and free. May or may not be equal to the amount of memory configured in the system.

available_memory - Informs about the amount memory that is available for increased usage if there is an increased memory need. This value is not based on a calculation of the other provided values and should give a better value of the amount of memory that actually is available than calculating a value based on the other values reported. This value is currently only present on newer Linux kernels. If this value is not available on Linux, you can use the sum of cached_memory, buffered_memory, and free_memory as an approximation.

free_memory - The amount of free memory available to the Erlang emulator for allocation.

system_total_memory - The amount of memory available to the whole operating system. This may well be equal to total_memory but not necessarily.

buffered_memory - The amount of memory the system uses for temporary storing raw disk blocks.

cached_memory - The amount of memory the system uses for cached files read from disk. On Linux, also memory marked as reclaimable in the kernel slab allocator will be added to this value.

total_swap - The amount of total amount of memory the system has available for disk swap.

free_swap - The amount of memory the system has available for disk swap.

Note

Note that new tagged tuples may be introduced in the result at any time without prior notice

Note that the order of the tuples in the resulting list is undefined and may change at any time.

All memory sizes are presented as number of bytes.

Returns the empty list [] if memsup is not available, or if the memory check times out.

set_check_interval(Minutes)

-spec set_check_interval(Minutes :: non_neg_integer()) -> ok.

Changes the time interval, given in minutes, for the periodic memory check.

The change will take effect after the next memory check and is non-persistent. That is, in case of a process restart, this value is forgotten and the default value will be used. See Configuration.

set_helper_timeout(Seconds)

-spec set_helper_timeout(Seconds :: non_neg_integer()) -> ok.

Changes the timeout value, given in seconds, for memory checks.

The change will take effect for the next memory check and is non-persistent. That is, in the case of a process restart, this value is forgotten and the default value will be used. See Configuration above.

set_procmem_high_watermark(Float)

-spec set_procmem_high_watermark(Float :: term()) -> ok.

Changes the threshold, given as a float, for process memory allocation.

The change will take effect during the next periodic memory check and is non-persistent. That is, in case of a process restart, this value is forgotten and the default value will be used. See Configuration.

set_sysmem_high_watermark(Float)

-spec set_sysmem_high_watermark(Float :: term()) -> ok.

Changes the threshold, given as a float, for system memory allocation.

The change will take effect during the next periodic memory check and is non-persistent. That is, in case of a process restart, this value is forgotten and the default value will be used. See Configuration above.

nteventlog

Interface to Windows Event Log

nteventlog provides a generic interface to the Windows event log. It is part of the OS_Mon application, see os_mon.

This module is used as the Windows backend for os_sup. See os_sup.

To retain backwards compatibility, this module can also be used to start a standalone nteventlog process which is not part of the OS_Mon supervision tree. When starting such a process, the user has to supply an identifier as well as a callback function to handle the messages.

The identifier, an arbitrary string, should be reused whenever the same application (or node) wants to start the process. nteventlog is informed about all events that have arrived to the eventlog since the last accepted message for the current identifier. As long as the same identifier is used, the same eventlog record will not be sent to nteventlog more than once (with the exception of when graved system failures arise, in which case the last records written before the failure may be sent to Erlang again after reboot).

If the event log is configured to wrap around automatically, records that have arrived to the log and been overwritten when nteventlog was not running are lost. However, it detects this state and loses no records that are not overwritten.

The callback function works as described in os_sup.

See Also

os_mon, os_sup

Windows NT documentation

Summary

Functions

start(Identifier, MFA)

Equivalent to start_link(Identifier, MFA) except that no link is created between nteventlog and the calling process.

start_link(Identifier, MFA)

This function starts the standalone nteventlog process and, if start_link/2 is used, links to it.

stop()

Stops nteventlog. Usually only used during development. The server does not have to be shut down gracefully to maintain its state.

Functions

start(Identifier, MFA)

-spec start(Identifier, MFA) -> Result
               when
                   Identifier :: string() | atom(),
                   MFA :: {Mod, Func, Args},
                   Mod :: atom(),
                   Func :: atom(),
                   Args :: [term()],
                   Result :: {ok, Pid} | {error, {already_started, Pid}},
                   Pid :: pid().

Equivalent to start_link(Identifier, MFA) except that no link is created between nteventlog and the calling process.

start_link(Identifier, MFA)

-spec start_link(Identifier, MFA) -> Result
                    when
                        Identifier :: string() | atom(),
                        MFA :: {Mod, Func, Args},
                        Mod :: atom(),
                        Func :: atom(),
                        Args :: [term()],
                        Result :: {ok, Pid} | {error, {already_started, Pid}},
                        Pid :: pid().

This function starts the standalone nteventlog process and, if start_link/2 is used, links to it.

Identifier is an identifier as described above.

MFA is the supplied callback function. When nteventlog receives information about a new event, this function will be called as apply(Mod, Func, [Event|Args]) where Event is a tuple

stop()

-spec stop() -> stopped.

Stops nteventlog. Usually only used during development. The server does not have to be shut down gracefully to maintain its state.

os_sup

Interface to OS System Messages

os_sup is a process providing a message passing service from the operating system to the error logger in the Erlang runtime system. It is part of the OS_Mon application, see os_mon. Available for Solaris and Windows.

Messages received from the operating system results in an user defined callback function being called. This function can do whatever filtering and formatting is necessary and then deploy any type of logging suitable for the user's application.

Solaris Operation

The Solaris (SunOS 5.x) messages are retrieved from the syslog daemon, syslogd.

Enabling the service includes actions which require root privileges, such as change of ownership and file privileges of an executable binary file, and creating a modified copy of the configuration file for syslogd. When os_sup is terminated, the service must be disabled, meaning the original configuration must be restored. Enabling/disabling can be done either outside or inside os_sup. See Configuration below.

Warning

This process cannot run in multiple instances on the same hardware. OS_Mon must be configured to start os_sup on one node only if two or more Erlang nodes execute on the same machine.

The format of received events is not defined.

Windows Operation

The Windows messages are retrieved from the eventlog file.

The nteventlog module is used to implement os_sup. See nteventlog. Note that the start functions of nteventlog does not need to be used, as in this case the process is started automatically as part of the OS_Mon supervision tree.

OS messages are formatted as a tuple {Time, Category, Facility, Severity, Message}:

Time = {MegaSecs, Secs, MicroSecs} - A time stamp as returned by the BIF now/0.

Category = string() - Usually one of "System", "Application" or "Security". Note that the NT eventlog viewer has another notion of category, which in most cases is totally meaningless and therefore not imported into Erlang. What is called a category here is one of the main three types of events occurring in a normal NT system.

Facility = string() - The source of the message, usually the name of the application that generated it. This could be almost any string. When matching messages from certain applications, the version number of the application may have to be accounted for. This is what the NT event viewer calls "source".

Severity = string() - One of "Error", "Warning", "Informational", "Audit_Success", "Audit_Faulure" or, in case of a currently unknown Windows NT version "Severity_Unknown".

Message = string() - Formatted exactly as it would be in the NT eventlog viewer. Binary data is not imported into Erlang.

Configuration

os_sup_mfa = {Module, Function, Args} - The callback function to use. Module and Function are atoms and Args is a list of terms. When an OS message Msg is received, this function is called as apply(Module, Function, [Msg | Args]).

Default is {os_sup, error_report, [Tag]} which will send the event to the error logger using error_logger:error_report(Tag, Msg). Tag is the value of os_sup_errortag, see below.

os_sup_errortag = atom() - This parameter defines the error report type used when messages are sent to error logger using the default callback function. Default is std_error, which means the events are handled by the standard event handler.

os_sup_enable = bool() - Solaris only. Defines if the service should be enabled (and disabled) inside (true) or outside (false) os_sup. For backwards compatibility reasons, the default is true. The recommended value is false, as the Erlang emulator should normally not be run with root privileges, as is required for enabling the service.

os_sup_own = string() - Solaris only. Defines the directory which contains the backup copy and the Erlang specific configuration files for syslogd, and a named pipe to receive the messages from syslogd. Default is "/etc".

os_sup_syslogconf = string() - Solaris only. Defines the full name of the configuration file for syslogd. Default is "/etc/syslog.conf".

See also

error_logger, os_mon

syslogd(1M), syslog.conf(4) in the Solaris documentation.

Summary

Functions

disable()

Equivalent to disable("/etc", "/etc/syslog.conf").

disable(Dir, Conf)

Disables the os_sup service. Needed on Solaris only.

enable()

Equivalent to enable("/etc", "/etc/syslog.conf").

enable(Dir, Conf)

Enables the os_sup service. Needed on Solaris only.

Functions

disable()

-spec disable() -> ok | {error, Res} when Res :: string().

Equivalent to disable("/etc", "/etc/syslog.conf").

disable(Dir, Conf)

-spec disable(Dir, Conf) -> ok | {error, Res} when Dir :: string(), Conf :: string(), Res :: string().

Disables the os_sup service. Needed on Solaris only.

If the configuration parameter os_sup_enable is false, this function is called automatically by os_sup, using the same arguments as when enable/2 was called.

If os_sup_enable is true, this function must be called after OS_Mon/os_sup is stopped. Dir defines the directory which contains the backup copy and the Erlang specific configuration files for syslogd, and a named pipe to receive the messages from syslogd. Defaults to "/etc". Conf defines the full name of the configuration file for syslogd. Default is "/etc/syslog.conf".

Results in a OS call to:

<PRIVDIR>/bin/mod_syslog nootp Dir Conf

where <PRIVDIR> is the priv directory of OS_Mon, code:priv_dir(os_mon).

Returns ok if this yields the expected result "0", and {error, Res} if it yields anything else.

Note

This function requires root privileges to succeed.

enable()

-spec enable() -> ok | {error, Res} when Res :: string().

Equivalent to enable("/etc", "/etc/syslog.conf").

enable(Dir, Conf)

-spec enable(Dir, Conf) -> ok | {error, Res} when Dir :: string(), Conf :: string(), Res :: string().

Enables the os_sup service. Needed on Solaris only.

If the configuration parameter os_sup_enable is false, this function is called automatically by os_sup, using the values of os_sup_own and os_sup_syslogconf as arguments.

If os_sup_enable is true, this function must be called before OS_Mon/os_sup is started. Dir defines the directory which contains the backup copy and the Erlang specific configuration files for syslogd, and a named pipe to receive the messages from syslogd. Defaults to "/etc". Conf defines the full name of the configuration file for syslogd. Default is "/etc/syslog.conf".

Results in a OS call to:

<PRIVDIR>/bin/mod_syslog otp Dir Conf

where <PRIVDIR> is the priv directory of OS_Mon, code:priv_dir(os_mon).

Returns ok if this yields the expected result "0", and {error, Res} if it yields anything else.

Note

This function requires root privileges to succeed.