PMGETCONTEXTHOSTNAME(3)

NAME
pmGetContextHostName - return the hostname associated with a Performance Co-Pilot context

C SYNOPSIS
#include <pcp/pmapi.h>

const char *pmGetContextHostName(int id);

cc ... -lpcp

DESCRIPTION
Given a valid PCP context identifier previously created with pmNewContext(3) or pmDupContext(3), the pmGetContextHostName function returns the hostname associated with id.

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 interface 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 local 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.

RETURN VALUE
If id is not a valid PCP context identifier, this function returns a zero length string and hence never fails.

PCP ENVIRONMENT
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 pmGetConfig(3) function.

SEE ALSO
PCPIntro(1), PMAPI(3), gethostname(3), pmDupContext(3), pmFetch(3), pmGetArchiveLabel(3), pmNewContext(3), pcp.conf(5) and pcp.env(5).