Standards
| Standards / Extensions |
C or C++ |
Dependencies |
|---|
XPG4.2
Single UNIX Specification, Version 3
|
both |
|
Format
#define _XOPEN_SOURCE_EXTENDED 1
#include <syslog.h>
void syslog(int priority, const char *message, … /* argument */);
General description
The syslog()
function sends a message to an implementation-specific logging facility,
which loads it in an appropriate system log, writes it to the system
console, forwards it to a list of users, or forwards it to the logging
facility on another host over the network. The logged message includes
a message header and a message body. The message header consists
of a facility indicator, a severity indicator, a timestamp, a tag
string, and optionally the process ID. The process ID is surrounded
by square brackets. The code point values for the square brackets
are taken from code page IBM-1047. The value for the left square bracket
is 0xAD. The value for the right square bracket is 0xBD.
The
message body is generated from the message and
following arguments in the same manner as if these were arguments
to the printf() function, except that occurrences of %m in
the format string pointed to by the message argument
are replaced by the error message string associated with the current
value of errno. A trailing newline character is added if needed.
Note: If
the total length of the format string and the parameters is greater
than 4096 bytes, then the results are undefined.
Values
of the
priority argument are formed by ORing
together a severity level values and an option facility value. If
no facility value is specified, the current default facility value
is used. Possible values of severity level include:
- LOG_ALERT
- A condition
that should be corrected immediately, such as a corrupted system database.
- LOG_CRIT
- Critical conditions,
such as hard device errors.
- LOG_DEBUG
- Messages that
contain information normally of use only when debugging a program.
- LOG_EMERG
- A Panic condition.
This is normally broadcast to all processes.
- LOG_ERR
- Errors.
- LOG_INFO
- Informational
messages.
- LOG_NOTICE
- Conditions
that are not error conditions, but that may require special handling.
- LOG_WARNING
- Warning messages.
The facility indicates the application or system
component generating the message. Possible facility values include:
- LOG_USER
- Message generated
by random processes. This is the default facility identifier if none
is specified.
- LOG_LOCAL0
- Reserved for
local use.
- LOG_LOCAL1
- Reserved for
local use.
- LOG_LOCAL2
- Reserved for
local use.
- LOG_LOCAL3
- Reserved for
local use.
- LOG_LOCAL4
- Reserved for
local use.
- LOG_LOCAL5
- Reserved for
local use.
- LOG_LOCAL6
- Reserved for
local use.
- LOG_LOCAL7
- Reserved for
local use.
Returned value
syslog() returns no values.