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NAME | C SYNOPSIS | DESCRIPTION | FLAGS VALUES | OPTIONS VIA ENVIRONMENT VARIABLES | RETURN VALUE | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
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PMGETOPTIONS(3) Library Functions Manual PMGETOPTIONS(3)
pmgetopt_r, pmGetOptions, pmGetContextOptions, pmFreeOptions,
pmUsageMessage - command line handling for PMAPI tools
#include <pcp/pmapi.h>
int pmgetopt_r(int argc, char *const *argv, pmOptions *opts);
int pmGetOptions(int argc, char *const *argv, pmOptions *opts);
int pmGetContextOptions(int ctx, pmOptions *opts);
void pmUsageMessage(pmOptions *opts);
void pmFreeOptions(pmOptions *opts);
cc ... -lpcp
The pmGetOptions function provides command line option processing
services for both monitor and collector PMAPI(3) tools. It is
modelled on the thread-safe variants of the GNU getopt_long(3) API,
and primarily differs in its focus on providing generalised
processing for the (de-facto) standard PCP command line options
described in PCPIntro(1). These common options include the host and
archive specification, time windows, timezones, sample counts, time
intervals, and so on.
The primary interface is pmGetOptions, which should be passed the
argc argument count and argv array, as passed to the main() function
on program invocation. The final opts argument describes the set of
long and short options the tools is prepared to process, and other
metadata regarding how those options should be processed.
The pmgetopt_r interface, used internally by pmGetOptions, behaves in
a similar fashion, but it does not perform any common option
processing. It is more suited to PCP collector processes, whereas
PCP monitor tools tend to use pmGetOptions.
The opts argument consists of an array of pmLongOpts entries
describing the arguments, as well as the enclosing pmOptions struct,
which are defined as follows (internal fields are not presented, for
brevity):
typedef struct {
const char * long_opt;
int has_arg;
int short_opt;
const char * argname;
const char * message;
} pmLongOptions;
typedef struct {
int version;
int flags;
const char * short_options;
pmLongOptions * long_options;
const char * short_usage;
pmOptionOverride override;
int index;
int optind;
int opterr;
int optopt;
char *optarg;
/* [internal fields, undocumented] */
int errors;
int context; /* PM_CONTEXT_{HOST,ARCHIVE,LOCAL} */
int nhosts;
int narchives;
char ** hosts;
char ** archives;
struct timeval start;
struct timeval finish;
struct timeval origin;
struct timeval interval;
char * align_optarg;
char * start_optarg;
char * finish_optarg;
char * origin_optarg;
char * guiport_optarg;
char * timezone;
int samples;
int guiport;
int padding;
unsigned int guiflag : 1;
unsigned int tzflag : 1;
unsigned int nsflag : 1;
unsigned int Lflag : 1;
unsigned int zeroes : 28;
} pmOptions;
The initial flags and version fields describe how the rest of the
pmOptions structure is to be interpreted. These fields can be
zeroed, specifying a default interpretation. Alternatively, the
PMAPI_VERSION macro can be used to specify the API level to use
(currently, values of 2 or less are allowed). The flags field can be
used to modify option processing behaviour as described in the
``FLAGS VALUES'' section below.
The array of long_options pmLongOpts structures must be terminated by
a sentinel and the PMAPI_OPTIONS_END macro can be used to effect this
termination. Individual records within the long_options array can be
of two types - options headers, or actual options. An options header
is constructed using the PMAPI_OPTIONS_HEADER macro, and is used for
usage message option grouping. Free form text can be inserted into
the usage message at any point using the PMAPI_OPTIONS_TEXT macro -
this is intended for additional explanatory text covering detailed
usage that is beyond the scope of the individual headers or options.
Otherwise, the array entry specifies an option. These should be
named (long_opt) if a long-option form is allowed, specify whether or
not they take an argument (has_arg), specify the single character
variant argument (short_opt) if a short-option form is allowed, and
finally specify how to present the option in the usage message. This
latter component consists of a short, one-word description of the
optional argument (argname) and a one-line description of what the
command-line option does (message).
The short_usage string is also used only when constructing the usage
message. It forms the component of the usage message that follows
the program name (i.e. argv[0]).
The optional short_options string is the normal getopt command-line
option specification string, using individual characters (those with
arguments are designated as such using the ':' character) - as used
by all getopt implementations.
A facility is provided to extend the existing set of common options
with additional options, as well as to re-task the standard options
into non-standard roles for individual tools. The latter is achieved
using the override method, which allows a callback function to be
provided which will be called on receipt of every argument, prior to
common processing. If this callback returns a non-zero value the
common processing will be short-circuited for that option, otherwise
processing continues. Thus, aach client tool is free to choose
exactly which of the standard options they wish to support - this can
be all, some, or none, and no matter what they choose, each tool
always has access to the long option parsing capability and the usage
message generation facility.
The remaining pmOptions structure fields are filled in as a result of
processing the arguments, and are largely self-explanatory. Further
discussion of these is deferred to the ``FLAGS VALUES'' section
below. The error field contains a count of errors detected during
option processing. These can be either usage or runtime errors, as
indicated by the flags field (set, and passed out to the caller).
Typically, a command line tool will fail to start successfully and
will produce an error message (e.g. via pmUsageMessage) if the error
field is non-zero at the end of either pmGetOptions or
pmGetContextOptions.
Some command line option post-processing can only be performed once
the tool has established a PMAPI context via pmNewContext(3). This
processing includes use of context-aware timezones (-z), and time
window processing (-A, -O, -S, -T) that may be affected by the
timezone, for example. The pmGetContextOptions function is available
for such situations, and it completes any remaining processing of
opts with respect to the ctx context identifier given.
The pmUsageMessage function generates a usage message for the tool,
and included both standard PCP options and custom options for each
tool, as specified by the pmLongOptions array. It supports grouping
of options (via PMAPI_OPTIONS_HEADER) as well as neat formatting of
all options - short and long - their arguments, and individual
explanatory messages. It will build this usage message using
pmprintf(3) upon which it will issue a single pmflush(3) before
returning to the caller, provided the PM_OPTFLAG_USAGE_ERR flag is
set in flags, which will happen automatically during option parsing,
when usage errors are detected.
In certain situations, such as recording lists of host specifications
or PCP archive paths, the pmGetOptions routine may allocate memory,
and store pointers to it within opts. Should a program wish to free
this memory before exiting, it can use the pmFreeOptions routine to
do so. This is safe to call irrespective of whether memory was
allocated dynamically, provided that opts was zeroed initially.
PM_OPTFLAG_INIT
Used internally within the library to indicate initialisation
has been done, so that on subsequent calls it will not be done
again.
PM_OPTFLAG_DONE
Used primarily internally within the library to indicate that
the final option processing has been completed. This
processing involves cross-referencing a number of the options,
to check for mutual exclusion, for example. There may be
other post-processing at this stage also, provided it does not
require a PMAPI context.
PM_OPTFLAG_MULTI
Allow more than one host or set of archives to be specified.
The default is to allow one source of metrics only, however
some of the more sophisticated tools permit multiple metric
sources, each of which is handled within a separate context.
See also PM_OPTFLAG_MIXED.
PM_OPTFLAG_USAGE_ERR
Indicates that the library has detected a command-line usage
error. This is an error such as when an option requires an
argument but none is supplied, or conflicting options are
specified (such as -s and -T).
PM_OPTFLAG_RUNTIME_ERR
Indicates that the library has detected an error at run time.
This is an error such as failing to retrieve timezone
information from pmcd(1) or failing to load an alternate
metric namespace from a local file (via the -n option).
PM_OPTFLAG_EXIT
Indicates a suggestion from the library that the tool exit
cleanly. This is used when the version number is requested,
for example (the -V option and PMOPT_VERSION macro).
PM_OPTFLAG_POSIX
Use strict POSIX command line argument handling. This means
options and following arguments will not be reordered, so
additional options cannot follow command line arguments. This
may be important for tools where the arguments can be negative
numbers, for example, as these should not be treated as
command line options in this case.
PM_OPTFLAG_MIXED
Allow both live and archive metric sources to be specified.
The default is to allow one type of metric context only,
however some of the more sophisticated tools permit multiple
context types. See also PM_OPTFLAG_MULTI.
PM_OPTFLAG_ENV_ONLY
Many options can be specified through the either the command
line or from similarly-named environment variables. This flag
disables all argument parsing, and only changes opts based on
the environment variables. This may be useful for tools
wishing to ensure no command line option conflicts occur
between their own set and the standard PCP option set (such as
an existing tool, reimplemented using PMAPI services).
PM_OPTFLAG_LONG_ONLY
Only process long options, not short options.
PM_OPTFLAG_BOUNDARIES
The default pmGetOptions behaviour is to parse the time window
options (namely, -A, -O, -S and -T), only if one of those
options has been specified on the command line. However, this
flag can be used (particularly with archive contexts) to find
the start and finish times associated with the context(s) even
if no time window options were specified. In the case of
multiple archives, the time window is defined as the time
window spanning all of the archives.
PM_OPTFLAG_STDOUT_TZ
The timezone being used will be reported on the standard
output stream during option parsing. The default behaviour is
to not report, but simply return timezone information via the
timezone (-Z) and tzflag (-z) fields in the opts structure.
PM_OPTFLAG_NOFLUSH
The final pmflush call issued by pmUsageMessage will be
skipped if this flag is set. This is useful in situations
where the caller wishes to append additional test to the
generated usage message before flushing.
PM_OPTFLAG_QUIET
Suppress messages from pmgetopt_r about unrecognised command
line options. This is the equivalent to setting the opterr
field in the opt parameter (which mimics the getopt variable
of the same name).
Some environment variables may be used as an alternative to the
command line options. The use of these mechanisms is primarily for
internal use by PCP tools. General users should choose the command
line options as this provides a clearer indication of intent, makes
debugging issues easier and avoids confusion over possible conflicts
between the command line options and the environment variables (where
the command line options usually ``win'').
The following table describes the environment variables that may be
used to set values as an alternative to command line options.
┌───────────────────┬────────┬──────────────────┬────────────────────┐
│ Environment │ Short │ Long │ Meaning │
│ │ Option │ Option │ │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_ALIGN_TIME │ -A │ --align │ align sample │
│ │ │ │ times on │
│ │ │ │ natural │
│ │ │ │ boundaries │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_ARCHIVE │ -a │ --archive │ metrics source │
│ │ │ │ is a PCP │
│ │ │ │ archive │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_ARCHIVE_LIST │ │ --archive-list │ comma-separated │
│ │ │ │ list of metric │
│ │ │ │ source archives │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_FOLIO │ │ --archive-folio │ metric source │
│ │ │ │ is a mkaf(1) │
│ │ │ │ archives folio │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_DEBUG │ -D │ --debug │ a comma- │
│ │ │ │ separated list │
│ │ │ │ of │
│ │ │ │ pmSetDebug(3) │
│ │ │ │ debugging │
│ │ │ │ options │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_GUIMODE │ -g │ --guimode │ start in GUI │
│ │ │ │ mode with new │
│ │ │ │ pmtime(1) time │
│ │ │ │ control │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_HOST │ -h │ --host │ metrics source │
│ │ │ │ is pmcd(1) on a │
│ │ │ │ host │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_HOST_LIST │ │ --host-list │ comma-separated │
│ │ │ │ list of metric │
│ │ │ │ source hosts │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_SPECLOCAL │ -K │ --spec-local │ optional │
│ │ │ │ additional DSO │
│ │ │ │ PMDA │
│ │ │ │ specification │
│ │ │ │ for local │
│ │ │ │ connection, see │
│ │ │ │ pmSpecLocalPMDA(3) │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_LOCALPMDA or │ -L │ --local-PMDA │ metrics source is │
│$PCP_LOCALMODE │ │ │ local connection │
│ │ │ │ to a DSO PMDA │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_NAMESPACE │ -n │ --namespace │ use an alternative │
│ │ │ │ Performance │
│ │ │ │ Metrics Name Space │
│ │ │ │ (PMNS) │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_UNIQNAMES │ -N │ --uniqnames │ like -n but only │
│ │ │ │ one name allowed │
│ │ │ │ for each metric in │
│ │ │ │ the PMNS │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_ORIGIN or │ -O │ --origin │ initial sample │
│$ORIGIN_TIME │ │ │ time within the │
│ │ │ │ time window │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_GUIPORT │ -p │ --guiport │ port for │
│ │ │ │ connection to an │
│ │ │ │ existing pmtime(1) │
│ │ │ │ time control │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_START_TIME │ -S │ --start │ start of the time │
│ │ │ │ window │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_SAMPLES │ -s │ --samples │ terminate after │
│ │ │ │ this many samples │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_FINISH_TIME │ -T │ --finish │ end of the time │
│ │ │ │ window │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_INTERVAL │ -t │ --interval │ sampling interval │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_TIMEZONE │ -Z │ --timezone │ set reporting │
│ │ │ │ timezone │
├───────────────────┼────────┼──────────────────┼────────────────────┤
│$PCP_HOSTZONE │ -z │ --hostzone │ set reporting │
│ │ │ │ timezone to local │
│ │ │ │ time of metrics │
│ │ │ │ source │
└───────────────────┴────────┴──────────────────┴────────────────────┘
The pmGetOptions function returns either when it detects a command-
line option that is not one of the standard PCP set, or when the end
of the command line options has been reached (at which point -1 is
returned). Both the pmgetopt_r and pmGetOptions routines return
control to the caller in the same way that a regular getopt call
would, with the return value indicating either the end of all
processing (-1), or the single character form of the option currently
being processed, or zero for the special long-option-only case. For
all option-processing cases, the opts structure is returned
containing filled out optarg, opterr, optopt, optind, and index
fields as normal (do NOT use the global optarg or optind from your
platform C library, these will NOT be modified).
pmGetOptions does not return to the caller when any of the standard
PCP options are being processed (although the override mechanism can
be used to still detect such options if needed).
The pmGetContextOptions function returns zero on success, or a
negative PCP error code on failure. The error field within the opts
parameter will also be non-zero in the latter case.
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). Values for these
variables may be obtained programmatically using the pmGetOptions(3)
function.
PCPIntro(1), pmcd(1), pminfo(1), pmstat(1), getopt(3),
getopt_long(3), pmNewContext(3), pmGetConfig(3), pmprintf(3),
pmflush(3) and PMAPI(3).
This page is part of the PCP (Performance Co-Pilot) project.
Information about the project can be found at ⟨http://www.pcp.io/⟩.
If you have a bug report for this manual page, send it to
pcp@groups.io. This page was obtained from the project's upstream
Git repository ⟨https://github.com/performancecopilot/pcp.git⟩ on
2018-02-02. (At that time, the date of the most recent commit that
was found in the repository was 2018-02-02.) If you discover any
rendering problems in this HTML version of the page, or you believe
there is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
Performance Co-Pilot PCP PMGETOPTIONS(3)
Pages that refer to this page: pcp2elasticsearch(1), pcp2graphite(1), pcp2influxdb(1), pcp2json(1), pcp2xlsx(1), pcp2xml(1), pcp2zabbix(1), pmgetopt(1), pmrep(1), pmdagetoptions(3), pmgetoptions(3), pmrep.conf(5)
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