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SENDSYSLOG(2) System Calls Manual SENDSYSLOG(2)


sendsyslogsend a message to syslogd


#include <sys/syslog.h>
#include <sys/types.h>
sendsyslog(const char *msg, size_t len, int flags);


The sendsyslog() function is used to transmit a syslog(3) formatted message direct to syslogd(8) without requiring the allocation of a socket. The msg is not NUL terminated and its len is limited to 8192 bytes. If LOG_CONS is specified in the flags argument, and syslogd(8) is not accepting messages, the message will be sent to the console. This is used internally by syslog_r(3), so that messages can be sent during difficult situations. If sending to syslogd(8) fails, dropped messages are counted. When syslogd(8) works again, a warning with the counter and error number is logged.


Upon successful completion, the value 0 is returned; otherwise the value -1 is returned and the global variable errno is set to indicate the error.


sendsyslog() can fail if:
An invalid user space address was specified for a parameter.
The socket requires that message be sent atomically, and the size of the message to be sent made this impossible.
The system was unable to allocate an internal buffer. The operation may succeed when buffers become available.
The message cannot be sent, likely because syslogd(8) is not running.


syslog_r(3), syslogd(8)


The sendsyslog() function call appeared in OpenBSD 5.6. The flags argument was added in OpenBSD 6.0.
September 25, 2017 OpenBSD-current