Provided by: pcp_5.3.6-1build1_amd64 
NAME
pmlc - configure active Performance Co-Pilot pmlogger(s) interactively
SYNOPSIS
pmlc [-eiPz?] [-h host] [-n pmnsfile] [-p port] [-Z timezone] [pid]
DESCRIPTION
pmlc may be used to change those metrics and instances which a pmlogger(1) writes to a Performance Co-
Pilot archive (see PCPIntro(1)), the frequency with which the metrics are collected and whether the
logging is mandatory, advisory, on or off. It also reports the current logging status of metrics and
instances. pmlc may be used to control pmlogger instances on remote hosts as well as those on the local
host.
Normally pmlc operates on the distributed Performance Metrics Name Space (PMNS), however if the -n option
is specified an alternative local PMNS is loaded from the file pmnsfile.
If the -P option is specified, pmlc will attempt to start with a connection to the primary pmlogger on
the local host. If the -p option is specified, then pmlc will attempt to start with a connection to the
pmlogger on this TCP/IP port. Alternatively, if pid is specified, a connection to the pmlogger instance
with that process id will be attempted on startup. The -h option may only be used if -P, -p port or a
pid is also specified. In that case pmlc will initially connect to the specified (remote) pmlogger
instance on host rather than the local host. If the connection to the specified pmlogger instance cannot
be established, pmlc will start with no connection. These options typically allow the same file of pmlc
commands to be directed to multiple pmlogger instances by varying the command line arguments. Note that
-P, -p port, pid and -h are used only when making an initial connection to a pmlogger instance. They are
not used as defaults if subsequent connections are made interactively (see the connect command below).
By default, pmlc reports the time of day according to the local timezone on the system where pmlc is run.
The -Z option changes the timezone to timezone in the format of the environment variable TZ as described
in environ(7). The -z option changes the timezone to the timezone of the pmlogger instance from which
information is being obtained. Only one of -z or -Z may be specified.
If standard input is from a tty, pmlc is interactive, with prompts. The -i flag may be used to force
interactive behavior, and is typically used in conjunction with -e to echo all command input on standard
output.
COMMANDS
The following commands may be used:
show [ loggers ] [ @host ]
Displays the process identities of all pmlogger instances running on the local host (or host, if
specified). The primary pmlogger pid is parenthesized because it can be referred to as "primary" as
well as by its pid.
connect pid [ @host ]
connect primary [ @host ]
Connects pmlc to the specified pmlogger process. Any existing connection to a pmlogger instance is
closed first. Each pmlogger instance will accept at most one connection at a time, so if the
connection is successfully established, your pmlc will be the only one controlling the pmlogger
instance it is connected to.
new volume
This command works only while a connection to a pmlogger instance is established. It tells the
pmlogger to close the current volume of the log and open a new volume. Closed volumes may be
archived, e.g. as part of a regular log management procedure to control the size of the physical log
files.
status
This command works only while a connection to a pmlogger instance is established. It prints
information about the state of the pmlogger instance and its associated log.
timezone local | logger | "timezone"
This command sets the time zone used when times are printed. local means use the time zone of the
machine that pmlc is running on. logger means use the time zone of the machine where the pmlogger
instance is running. Alternatively an explicit timezone enclosed in quotes may be supplied (refer to
TZ in environ(7) for details). The default time zone is local unless one of the -z or -Z options has
been supplied on the command line.
flush
This command works only while a connection to a pmlogger instance is established, and requests the
pmlogger instance to flush to disk all buffers associated with the current archive. For old-timers,
sync is a synonym for flush. In current versions of pmlogger(1) all writes are unbuffered and
aligned with the logical records in the external files, so this command achieves nothing, but is
retained for backwards compatibility.
disconnect
Disconnect pmlc from the current pmlogger instance, if any.
sleep delay
Pause pmlc for delay milliseconds. This may be helpful in scripted uses of pmlc to allow the current
pmlogger instance to make progress on recent requests before interrogating the status.
help
Displays a summary of the available commands.
h and ? are synonyms for help.
quit
Exits from pmlc.
The remaining commands query and change the logging state of metrics and instances. They will work only
if pmlc has a connection to a pmlogger instance. Metrics may be specified as fully qualified names (e.g.
hinv.ncpu) or subtrees of the PMNS (e.g. hinv) which are expanded to include all metrics in the subtree
(e.g. hinv.ncpu, hinv.cpuclock, etc.). Lists of metrics may be specified by enclosing them in braces
with spaces or a comma between metrics (e.g. {hinv.ncpu hinv.ndisk}). Subtrees of metrics may be
included in such lists.
Each individual metric specification may be further qualified with a space or comma separated list of
instances in square brackets (e.g. kernel.all.load["1 minute", "5 minute"]). External instance names or
numeric internal instance identifiers or both may be used in the same list (e.g.
sample.colour.[red,1,"blue"]). If an instance qualification is applied to a subtree of the PMNS all of
the metrics in the subtree must have the same instance domain. Instance qualifications may not be
applied to entire lists of metrics but may appear inside such lists.
If no instances are specified for a metric, all instances are used. All instances means all instances
available at the time the pmlogger instance in question fetches the metrics for logging. If an instance
domain changes over time this is not always the same as the set of instances displayed by pmlc, which can
only display the currently available instances. To prevent unintentional errors, only the instances that
are currently available to pmlc may appear in instance specifications.
query metriclist
The current logging state of each metric (and instances, where applicable) in metriclist is
displayed. This includes the logging state (e.g. on, maybe, off) and the logging interval for each
metric (and instance) requested. The following abbreviations pertaining to metrics (and instances)
may appear in the output: adv, advisory; mand, mandatory; nl, not in the log; na, in the log but not
currently available from its Performance Metrics Domain Agent (PMDA). Where appropriate, an instance
name will appear last on a line preceded by its numeric internal instance identifier.
[ log ] mandatory on interval metriclist
This form of the log command turns on logging for the metrics (and any instances) in metriclist.
interval specifies how often the specified metrics/instances should be logged. once indicates that
the metrics/instances should appear at most once in the log. More often one would use the optional
keyword every followed by a positive number and one of millisecond (or msec), second (or sec), minute
(or min), hour or their plurals.
Note that the keyword default which may be used for the default interval in a pmlogger(1)
configuration file cannot be used in pmlc.
Internal limitations require the interval to be less than (approximately) 74 hours. An interval
value of zero is a synonym for once.
[ log ] mandatory off metriclist
This tells the pmlogger instance not to log any of the metrics/instances in metriclist.
[ log ] mandatory maybe metriclist
This tells the pmlogger instance to honor any subsequent advisory logging requests for the
metrics/instances in metriclist. If the current logging state of the metrics/instances is mandatory
(either on or off) the new state will be set to maybe (effectively advisory off). If the current
state of the metrics/instances is already advisory (either on or off) the state(s) for the
metrics/instances will remain as they are.
[ log ] advisory on interval metriclist
[ log ] advisory off metriclist
Advisory logging is only applicable if the last logging state specified for a metric/instance was
"mandatory maybe" (which permits subsequent advisory logging control) or if the logging state is
already advisory. These two statements turn advisory logging on or off (respectively) for the
specified metrics/instances.
The interpretation for interval is as above for the mandatory case.
There is no continuation character required for commands that span lines.
The word at may be used interchangeably with @.
A request to log all instances of a metric will supersede any prior request to log either all or specific
instances of a metric (if the request specifies a permissible transition in the logging state). A
request to log specific instances of a metric when all instances of a metric are already being logged is
refused by pmlogger.
OPTIONS
The available command line options are:
-e, --echo
Echo all command input on standard output.
-h host, --host=host
Connect pmlogger on host, rather than on the default localhost.
-i, --interactive
Force interactive behavior.
-n pmnsfile, --namespace=pmnsfile
Load an alternative Performance Metrics Name Space (PMNS(5)) from the file pmnsfile.
-p port, --port=port
Connect to the primary pmlogger on TCP/IP port port.
-P, --primary
Connect to the primary pmlogger.
-z, --logzone
Use local time of the pmlogger as the reporting timezone.
-Z timezone, --timezone=timezone
Use timezone for the date and time. Timezone is in the format of the environment variable TZ as
described in environ(7).
-?, --help
Display usage message and exit.
ACCESS CONTROL
pmlc may have restricted access to and control over pmlogger(1) processes.
If a pmlogger(1) is unable to export its control information to the local pmcd(1), then that pmlogger(1)
cannot cannot be connected to nor controlled by pmlc. In practice, this means the pmlogger(1) process
has to be owned by the user ``pcp'' and/or the group ``pcp''. If pmlogger(1) is running on the host
``foo'' then use ``pminfo -f -h foo pmcd.pmlogger'' to verify that the pmlogger(1) of interest is known
to pmcd(1), alternatively pmlogger(1) instances that are not reported from the pmlc show loggers @foo
command are not known to pmcd(1) on the host ``foo''.
If pmlogger(1) is launched with a configuration file that contains an [access] section, then pmlc will be
unable to connect to that pmlogger(1) unless the access controls allow some access from the host where
pmlc is being run. Minimally this requires the enquire access to be permitted in the pmlogger(1) access
control section.
If pmlc is able to connect to the pmlogger(1) of interest, then the following table summarizes the
permissions needed to perform different pmlc commands:
┌──────────────────┬───────────────────────────────────────┐
│ pmlc command │ Required pmlogger access │
├──────────────────┼───────────────────────────────────────┤
│show loggers │ Any │
│connect │ Any of enquire, advisory or mandatory │
│status │ Any of enquire, advisory or mandatory │
│query ... │ Any of enquire, advisory or mandatory │
│disconnect │ Any │
│log advisory ... │ advisory │
│log mandatory ... │ mandatory │
│new volume │ mandatory │
└──────────────────┴───────────────────────────────────────┘
CAVEATS
If all instances of a metric are being logged and a request is made to log specific instances of the
metric with the same state and frequency, the request may appear to succeed, even though pmlogger has
refused the request. This is not normally a problem, as the required information will still be placed
into the log by pmlogger.
However in the case where the metric is to be logged once, the outcome is not what might be expected.
When pmlogger receives a request to log a metric once, it places the current value(s) of the metric into
the log as soon as it can, regardless of whether the metric is already in the log. This may be used to
force values into the log. When a request to log specific instances of a metric arrives and is refused
because all instances of the metric are already being logged, pmlogger does not place values for the
instances requested into the log. It returns the current logging state for each instance requested to
pmlc. The requested and returned states are identical, so pmlc doesn't raise an error as it should.
To ensure that only certain instances of a metric are being logged, one should always turn off logging
for all instances of the metric prior to turning on logging for the specific instances required.
DIAGNOSTICS
Most error or warning messages are self-explanatory. A message of the form
Warning: unable to change logging state for...
followed by a list of metrics (and possibly instances) indicates that pmlogger refused the request for
the metrics (and instances) that appear. Any metrics (and instances) that were specified but do not
appear in the message have had their logging state updated successfully (no news is good news). Usually
this warning results from requesting advisory logging when a mandatory control is already in place, or
requesting logging for specific instances when all instances are already being logged.
ENVIRONMENT
If the PMLOGGER_REQUEST_TIMEOUT environment variable is not set or set to 0 (zero), then pmlc will block
until a connection is established with pmlogger(1) on the requested port. If PMLOGGER_REQUEST_TIMEOUT is
set to a value greater than zero, then pmlc will fail with an error after that many seconds if a
connection isn't established. This may be used by administrative scripts such as pmlogger_daily(1) to
poll pmlogger when is starting up until it is ready and listening on it's control port.
PCP ENVIRONMENT
Environment variables with the prefix PCP_ are used to parameterize the file and directory names used by
PCP. On each installation, the file /etc/pcp.conf contains the local values for these variables. The
$PCP_CONF variable may be used to specify an alternative configuration file, as described in pcp.conf(5).
SEE ALSO
PCPIntro(1), pmcd(1), pmdumplog(1), pmlogger(1), pcp.conf(5), pcp.env(5), PMNS(5) and environ(7).