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NAME | C SYNOPSIS | DESCRIPTION | SEE ALSO | COLOPHON |
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PMOPENLOG(3) Library Functions Manual PMOPENLOG(3)
pmOpenLog - create a log file for diagnostics and debug output
#include <pcp/pmapi.h>
FILE *pmOpenLog(const char *progname, const char *logname,
FILE *oldstream, int *status);
cc ... -lpcp
pmOpenLog reassigns the standard I/O stream oldstream (normally
stderr) to be associated with the file logname.
If logname is not "-" and the file already exists, it will be re‐
named to logname.prev else removed. Due to permissions restric‐
tions, the rename or removal may not succeed, but in the common
use cases logname.prev remains with the contents of the previous
version of logname. Then logname is recreated if possible (to en‐
sure correct ownership and permissions from the caller to pmOpen‐
Log).
As a special case, if logname is "-" then no renaming, removal or
reopening is performed and the function simply sets status to 1
and returns oldstream. This is useful when the caller wants diag‐
nostics on oldstream stream (normally stderr) rather than a file,
e.g. pmlogger -l- or pmcd -f -l-. Logging to stderr is also use‐
ful for PMDAs in a containerized environment where it is benefi‐
cial 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 pm‐
cd.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 mes‐
sage to logname
Log finished date and time
when the processes exits.
progname is only used to annotate messages.
atexit(3) and freopen(3).
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
2025-02-02. (At that time, the date of the most recent commit
that was found in the repository was 2025-01-30.) 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 PMOPENLOG(3)
Pages that refer to this page: pmnotifyerr(3), __pmnotifythrottle(3)
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HTML rendering created 2025-02-02 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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