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NAME | C SYNOPSIS | DESCRIPTION | RETURN VALUE | NOTES | PCP ENVIRONMENT | SEE ALSO | COLOPHON |
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PMGETCONTEXTHOSTNAME(3) Library Functions Manual PMGETCONTEXTHOSTNAME(3)
pmGetHostName, pmGetContextHostName, pmGetContextHostName_r -
return the hostname associated with a Performance Co-Pilot context
#include <pcp/pmapi.h>
int pmGetHostName(int id, char *buf, int buflen);
const char *pmGetContextHostName(int id);
char *pmGetContextHostName_r(int id, char *buf, int buflen);
cc ... -lpcp
Given a valid PCP context identifier previously created with
pmNewContext(3) or pmDupContext(3), the pmGetContextHostName func‐
tion returns the hostname associated with id. The pmGetContex‐
tHostName_r function does the same, but stores the result in a
user-supplied buffer buf of length buflen, which should have room
for at least MAXHOSTNAMELEN bytes. The pmGetHostName function be‐
haves similarly again, but returns a status code to indicate suc‐
cess or failure.
If the context id is associated with an archive source of data,
the hostname returned is extracted from the archive label using
pmGetArchiveLabel(3).
For live contexts, an attempt will first be made to retrieve the
hostname from the PCP collector system using pmFetch(3) with the
pmcd.hostname metric. This allows client tools using this inter‐
face to retrieve an accurate host identifier even in the presence
of port forwarding and tunnelled connections.
Should this not succeed, then a fallback method is used. For lo‐
cal contexts - with local meaning any of DSO, ``localhost'' or
Unix domain socket connection - a hostname will be sought via
gethostname(3). For other contexts, the hostname extracted from
the initial context host specification will be used.
If id is not a valid PCP context identifier, the returned hostname
is a zero length string.
On failure, the return code of pmGetHostName is a negative PMAPI
error code which can be processed by pmErrStr_r(3) for diagnostics
relating to the failure to obtain the context hostname.
pmGetContextHostName returns a pointer to a static buffer, so the
returned value is only valid until the next call to pmGetContex‐
tHostName and hence is not thread-safe. Multi-threaded applica‐
tions should use pmGetHostName or pmGetContextHostName_r instead.
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.
PCPIntro(1), PMAPI(3), gethostname(3), pmDupContext(3),
pmErrStr_r(3), pmFetch(3), pmGetArchiveLabel(3), pmNewContext(3),
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 PMGETCONTEXTHOSTNAME(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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