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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;
#if PMAPI_VERSION == PMAPI_VERSION_3
struct timeval unused[4];
#else
struct timeval start;
struct timeval finish;
struct timeval origin;
struct timeval interval;
#endif
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;
#if PMAPI_VERSION == PMAPI_VERSION_3
struct timespec start;
struct timespec finish;
struct timespec origin;
struct timespec interval;
#endif
} 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 3 or less are allowed). Version 2 is the
default, version 3 introduces high resolution time window and
interval fields (i.e. using struct timespec as opposed to struct
timeval). When using the latter form, before including
<pcp/pmapi.h> the PMAPI_VERSION macro must be set to 3 to ensure
the correct layout of pmOptions structure is used by the
application. 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,
each 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 │
│ $PCP_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 2024-06-14.
(At that time, the date of the most recent commit that was found
in the repository was 2024-06-14.) 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: chkhelp(1), collectl2pcp(1), dbpmda(1), newhelp(1), pcp(1), pcp2arrow(1), pcp2elasticsearch(1), pcp2graphite(1), pcp2influxdb(1), pcp2json(1), pcp2openmetrics(1), pcp2spark(1), pcp2template(1), pcp2xlsx(1), pcp2xml(1), pcp2zabbix(1), pcp-atop(1), pcp-atopsar(1), pcp-buddyinfo(1), pcp-dmcache(1), pcp-dstat(1), pcp-free(1), pcpintro(1), pcp-iostat(1), pcp-ipcs(1), pcp-meminfo(1), pcp-mpstat(1), pcp-netstat(1), pcp-numastat(1), pcp-pidstat(1), pcp-ps(1), pcp-slabinfo(1), pcp-ss(1), pcp-tapestat(1), pcp-uptime(1), pcp-verify(1), pcp-zoneinfo(1), pmcd(1), pmclient(1), pmcpp(1), pmdumptext(1), pmgetopt(1), pminfo(1), pmlogextract(1), pmlogrewrite(1), pmprobe(1), pmproxy(1), pmrep(1), pmsearch(1), pmseries(1), pmstat(1), pmval(1), sar2pcp(1), sheet2pcp(1), pmdagetoptions(3), pmgetoptions(3), pcp-dstat(5), pmrep.conf(5)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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