NAME

       pmOpenLog - create a log file for diagnostics and debug output

C SYNOPSIS

       #include <pcp/pmapi.h>

       FILE *pmOpenLog(const char *progname, const char *logname, FILE *oldstream, int *status);

       cc ... -lpcp

DESCRIPTION

       pmOpenLog  reassigns  the  standard I/O stream oldstream (normally stderr) to be associated with the file
       logname.  If logname is not "-" and already exists, it will be removed and recreated if possible (to  en‐
       sure correct ownership and permissions from the caller to pmOpenLog).

       As  a  special  case, if logname is "-" then no removal or reopening is performed and the function simply
       sets status to 1 and returns oldstream.  This is useful when the caller wants  diagnostics  on  oldstream
       stream (normally stderr) rather than a file, e.g.  pmlogger -l- or pmcd -f -l-.  Logging to stderr is al‐
       so useful for PMDAs in a containerized environment where it is beneficial for all PMDA logs to be written
       to  pmcd's  stderr  stream (and thus to a single destination), whether that is a file such as pmcd.log or
       the original stream inherited from the shell.

       On return, the function value is the standard I/O stream, possibly replacing oldstream.  In the event  of
       an error, the return value will be oldstream unchanged and status will be 0.

       For success, status is 1, and a standard preamble is written to logname
            Log for progname on hostname started date and time
       and an atexit(3) handler is installed to write the postscript message to logname
            Log finished date and time
       when the processes exits.

       progname is only used to annotate messages.

SEE ALSO

       atexit(3) and freopen(3).

Performance Co-Pilot                                   PCP                                          PMOPENLOG(3)