pmgetoptions(3) - Linux manual page (original) (raw)
PMGETOPTIONS(3) Library Functions Manual PMGETOPTIONS(3)
NAME top
**pmgetopt_r**, **pmGetOptions**, **pmGetContextOptions**, **pmFreeOptions**,
**pmUsageMessage** - command line handling for PMAPI toolsC SYNOPSIS top
**#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**DESCRIPTION top
The **pmGetOptions** function provides command line option processing
services for both monitor and collector [PMAPI(3)](../man3/PMAPI.3.html) tools. It is
modelled on the thread-safe variants of the GNU [getopt_long(3)](../man3/getopt%5Flong.3.html)
API, and primarily differs in its focus on providing generalised
processing for the (de-facto) standard PCP command line options
described in [PCPIntro(1)](../man1/PCPIntro.1.html). 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 _longoptions_ 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
_longoptions_ 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
(_longopt_) if a long-option form is allowed, specify whether or
not they take an argument (_hasarg_), specify the single character
variant argument (_shortopt_) 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 _shortusage_ 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 _shortoptions_ 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)](../man3/pmNewContext.3.html).
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)](../man3/pmprintf.3.html) upon which it will issue a single
[pmflush(3)](../man3/pmflush.3.html) 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.FLAGS VALUES top
**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)](../man1/pmcd.1.html) 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).OPTIONS VIA ENVIRONMENT VARIABLES top
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)](../man1/mkaf.1.html) │
│ │ │ │ archives folio │
├───────────────────┼────────┼─────────────────┼────────────────────┤
│ **$PCP_DEBUG** │ **-D** │**--debug** │ a comma- │
│ │ │ │ separated list │
│ │ │ │ of │
│ │ │ │ [pmSetDebug(3)](../man3/pmSetDebug.3.html) │
│ │ │ │ debugging │
│ │ │ │ options │
├───────────────────┼────────┼─────────────────┼────────────────────┤
│ **$PCP_GUIMODE** │ **-g** │**--guimode** │ start in GUI │
│ │ │ │ mode with new │
│ │ │ │ [pmtime(1)](../man1/pmtime.1.html) time │
│ │ │ │ control │
├───────────────────┼────────┼─────────────────┼────────────────────┤
│ **$PCP_HOST** │ **-h** │**--host** │ metrics source │
│ │ │ │ is [pmcd(1)](../man1/pmcd.1.html) on a │
│ │ │ │ host │
├───────────────────┼────────┼─────────────────┼────────────────────┤
│ **$PCP_HOST_LIST** │ │**--host-list** │ comma-separated │
│ │ │ │ list of metric │
│ │ │ │ source hosts │
├───────────────────┼────────┼─────────────────┼────────────────────┤
│ **$PCP_SPECLOCAL** │ **-K** │**--spec-local** │ optional │
│ │ │ │ additional DSO │
│ │ │ │ PMDA │
│ │ │ │ specification │
│ │ │ │ for local │
│ │ │ │ connection, see │
│ │ │ │ [pmSpecLocalPMDA(3)](../man3/pmSpecLocalPMDA.3.html) │
├───────────────────┼────────┼─────────────────┼────────────────────┤
│ **$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)](../man1/pmtime.1.html) │
│ │ │ │ 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 │
└───────────────────┴────────┴─────────────────┴────────────────────┘RETURN VALUE top
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.PCP ENVIRONMENT top
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)](../man5/pcp.conf.5.html).
Values for these variables may be obtained programmatically using
the [pmGetOptions(3)](../man3/pmGetOptions.3.html) function.SEE ALSO top
[PCPIntro(1)](../man1/PCPIntro.1.html), [pmcd(1)](../man1/pmcd.1.html), [pminfo(1)](../man1/pminfo.1.html), [pmstat(1)](../man1/pmstat.1.html), [getopt(3)](../man3/getopt.3.html),
[getopt_long(3)](../man3/getopt%5Flong.3.html), [pmNewContext(3)](../man3/pmNewContext.3.html), [pmGetConfig(3)](../man3/pmGetConfig.3.html), [pmprintf(3)](../man3/pmprintf.3.html),
[pmflush(3)](../man3/pmflush.3.html) and [PMAPI(3)](../man3/PMAPI.3.html).COLOPHON top
This page is part of the _PCP_ (Performance Co-Pilot) project.
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man-pages@man7.orgPerformance Co-Pilot PCP PMGETOPTIONS(3)
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