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NAME | C SYNOPSIS | DESCRIPTION | COMPATIBILITY | DIAGNOSTICS | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
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PMGETARCHIVELABEL(3) Library Functions Manual PMGETARCHIVELABEL(3)
pmGetArchiveLabel - fetch the label record from a set of
performance metrics archives
#include <pcp/pmapi.h>
int pmGetArchiveLabel(pmLogLabel *lp);
cc ... -lpcp
Within the framework of the Performance Co-Pilot (PCP), archives
of performance metrics values may be accumulated and saved using
the program pmlogger(1) and the LOGIMPORT(3) programming inter‐
face.
The routines pmGetArchiveLabel may be used to fetch the label
record from a set of archives that has already been opened using
pmNewContext(3), or pmDupContext(3), and thereby associated with
the current Performance Metrics Application Programming Interface
(PMAPI) context.
The result returned via the pointer lp is a structure that must be
pre-allocated by the caller and has the following format (defined
in pmapi.h).
typedef struct {
int magic; /* PM_LOG_MAGIC | archive format version no. */
pid_t pid; /* PID of logger */
struct timespec start; /* start of this archive */
char hostname[PM_MAX_HOSTNAMELEN]; /* collection host full name */
char timezone[PM_MAX_TIMEZONELEN]; /* generic, squashed $TZ */
char zoneinfo[PM_MAX_ZONEINFOLEN]; /* local platform $TZ */
} pmLogLabel;
pmGetArchiveLabel can be used with either version 2 or version 3
archives, however some mapping may be required with the older ver‐
sion 2 archives, e.g. the start time only has microsecond resolu‐
tion and the zoneinfo field is not present. For detailed informa‐
tion about the archive on-disk format, refer to LOGARCHIVE(5).
For an application using pmGetArchiveLabel, the most useful infor‐
mation from the archive label is likely to be in the fields start,
hostname, timezone, and zoneinfo.
The zoneinfo field contains the most detailed timezone information
available, and should be used if present (non-zero length string).
It will only not be present in the case of version 2 archives -
this is a new field added as part of the version 3 format. The
timezone field will always be present, however it is the
'squashed' timezone value and in certain situations is not the
most accurate timezone.
For older applications using pmGetArchiveLabel, the most useful
information from the archive label is likely to be in the fields
ll_start, ll_hostname or ll_tz. Note that the size of the
ll_hostname field is PM_LOG_MAXHOSTLEN (64 bytes) which is less
than MAXHOSTNAMELEN (see gethostbyname(3)) on some platforms.
These semantics are necessary to retain backwards compatibility
with the PCP archive file format.
pmGetArchiveLabel return zero for success.
Prior to PCP 7.0 and libpcp.so.4 the pmLogLabel structure was
somewhat different. To support PMAPI transition, the old inter‐
face and semantics can be used if applications are linked with
libpcp.so.3 or recompiled with -DPMAPI_VERSION=2.
For a time in PCP 6.x there was a routine with the same semantics
as the current pmGetArchiveLabel called pmGetHighResArchiveLabel
and a structure with same definition as pmLogLabel called pmHigh‐
ResLogLabel although these are now deprecated and compile-time
support for pmGetHighResArchiveLabel and pmHighResLogLabel will be
removed in a future release.
PM_ERR_NOCONTEXT
the current PMAPI context is either invalid, or not associ‐
ated with a set of archives
Environment variables with the prefix PCP_ are used to parameter‐
ize the file and directory names used by PCP. On each installa‐
tion, the file /etc/pcp.conf contains the local values for these
variables. The $PCP_CONF variable may be used to specify an al‐
ternative configuration file, as described in pcp.conf(5). Values
for these variables may be obtained programmatically using the
pmGetConfig(3) function.
pmlogger(1), LOGIMPORT(3), PMAPI(3), pmDupContext(3),
pmGetConfig(3), pmNewContext(3), LOGARCHIVE(5), pcp.conf(5) and
pcp.env(5).
This page is part of the PCP (Performance Co-Pilot) project. In‐
formation 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
2025-08-11. (At that time, the date of the most recent commit
that was found in the repository was 2025-08-11.) 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 PMGETARCHIVELABEL(3)
Pages that refer to this page: pmgetarchiveend(3), pmgetcontexthostname(3), __pmparsetime(3), pmparsetimewindow(3), pmsetmode(3)
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HTML rendering created 2025-09-06 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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