NAME

       pmGetArchiveLabel - fetch the label record from a set of performance metrics archive logs

C SYNOPSIS

       #include <pcp/pmapi.h>

       int pmGetArchiveLabel(pmLogLabel *lp);

       cc ... -lpcp

DESCRIPTION

       Within the framework of the Performance Co-Pilot (PCP), archive logs of performance metrics values may be
       accumulated and saved using the program pmlogger(1).

       The routine pmGetArchiveLabel may be used to fetch the label record from a set of archive logs  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).

         /*
          * Label Record at the start of every log file
          */
         typedef struct {
           int        ll_magic;    /* PM_LOG_MAGIC | log format version no. */
           pid_t      ll_pid;      /* PID of logger */
           struct timeval ll_start;/* start of this log */
           char       ll_hostname[PM_LOG_MAXHOSTLEN]; /* name of collection host */
           char       ll_tz[40];   /* $TZ at collection host */
         } pmLogLabel;

       For  an  application,  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 returns zero for success.

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

       pmlogger(1), PMAPI(3), pmDupContext(3), pmGetConfig(3), pmNewContext(3), pcp.conf(5) and pcp.env(5).

DIAGNOSTICS

       PM_ERR_NOCONTEXT
              the current PMAPI context is either invalid, or not associated with a set of archive logs