2.11BSD/man/cat3/syslog.0
SYSLOG(3) UNIX Programmer's Manual SYSLOG(3)
NAME
syslog , vsyslog , openlog , closelog , setlogmask - control
system log
SYNOPSIS
#include <syslog.h>
#include <varargs.h>
void syslog(priority, message, ...);
int priority;
char *message;
void vsyslog(priority, message, args);
int priority;
char *message;
va_list args;
void openlog(ident, logopt, facility);
char *ident;
int logopt;
int facility;
void closelog();
int setlogmask(maskpri);
int maskpri;
DESCRIPTION
The _s_y_s_l_o_g() function writes _m_e_s_s_a_g_e to the system message
logger. The message is then written to the system console,
log files, logged-in users, or forwarded to other machines
as appropriate. (See _s_y_s_l_o_g_d(8)).
The message is identical to a _p_r_i_n_t_f(3) format string,
except that %m is replaced by the current error message as
denoted by the global variable _e_r_r_n_o. See _s_t_r_e_r_r_o_r(3)). A
trailing newline is added if none is present.
The _v_s_y_s_l_o_g() function is an alternate form in which the
arguments have already been captured using the variable-
length argument facilities of _v_a_r_a_r_g_s(3).
The message is tagged with _p_r_i_o_r_i_t_y. Priorities are encoded
as a _f_a_c_i_l_i_t_y and a _l_e_v_e_l. The facility describes the part
of the system generating the message. The level is selected
from the following _o_r_d_e_r_e_d (high to low) list:
LOG_EMERG A panic condition. This is normally broad-
cast to all users.
LOG_ALERT A condition that should be corrected immedi-
ately, such as a corrupted system database.
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LOG_CRIT Critical conditions, e.g., hard device
errors.
LOG_ERR Errors.
LOG_WARNING Warning messages.
LOG_NOTICE Conditions that are not error conditions,
but should possibly be handled specially.
LOG_INFO Informational messages.
LOG_DEBUG Messages that contain information normally
of use only when debugging a program.
The _o_p_e_n_l_o_g() function provides for more specialized pro-
cessing of the messages sent by _s_y_s_l_o_g() and _v_s_y_s_l_o_g(). The
parameter _i_d_e_n_t is a string that will be prepended to every
message. The _l_o_g_o_p_t argument is a bit field specifying log-
ging options, which is formed by OR'ing one or more of the
following values:
LOG_CONS If _s_y_s_l_o_g cannot pass the message to _s_y_s_l_o_g_d
it will attempt to write the message to the
console (/dev/console).
LOG_NDELAY Open the connection to _s_y_s_l_o_g_d immediately.
Normally the open is delayed until the first
message is logged. Useful for programs that
need to manage the order in which file
descriptors are allocated.
LOG_PERROR Write the message to standard error output as
well to the system log.
LOG_PID Log the process id with each message: useful
for identifying instantiations of daemons.
The _f_a_c_i_l_i_t_y parameter encodes a default facility to be
assigned to all messages that do not have an explicit facil-
ity encoded:
LOG_AUTH The authorization system: _l_o_g_i_n(1), _s_u(1),
_g_e_t_t_y(8), etc.
LOG_AUTHPRIV The same as LOG_AUTH , but logged to a file
readable only by selected individuals.
LOG_CRON The clock daemon.
LOG_DAEMON System daemons, such as _r_o_u_t_e_d(8), that are
not provided for explicitly by other
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facilities.
LOG_KERN Messages generated by the kernel. These can-
not be generated by any user processes.
LOG_LPR The line printer spooling system: _l_p_r(1),
_l_p_c(8), _l_p_d(8), etc.
LOG_MAIL The mail system.
LOG_NEWS The network news system.
LOG_SYSLOG Messages generated internally by _s_y_s_l_o_g_d(8).
LOG_USER Messages generated by random user processes.
This is the default facility identifier if
none is specified.
LOG_UUCP The uucp system.
LOG_LOCAL0 Reserved for local use. Similarly for
LOG_LOCAL1 through LOG_LOCAL7.
The _c_l_o_s_e_l_o_g function can be used to close the log file.
The _s_e_t_l_o_g_m_a_s_k function sets the log priority mask to
_m_a_s_k_p_r_i and returns the previous mask. Calls to _s_y_s_l_o_g with
a priority not set in _m_a_s_k_p_r_i are rejected. The mask for an
individual priority _p_r_i is calculated by the macro
_L_O_G__M_A_S_K(pri). The mask for all priorities up to and
including _t_o_p_p_r_i is given by the macro _L_O_G__U_P_T_O(toppri).
The default allows all priorities to be logged.
RETURN VALUES
The routines _c_l_o_s_e_l_o_g(), _o_p_e_n_l_o_g(), _s_y_s_l_o_g() and _v_s_y_s_l_o_g()
return no value.
The routine _s_e_t_l_o_g_m_a_s_k() always returns the previous log
mask level.
EXAMPLES
syslog(LOG_ALERT, "who: internal error 23");
openlog("ftpd", LOG_PID, LOG_DAEMON);
setlogmask(LOG_UPTO(LOG_ERR)); syslog(LOG_INFO,
"Connection from host %d", CallingHost);
syslog(LOG_INFO|LOG_LOCAL2, "foobar error: %m");
SEE ALSO
_l_o_g_g_e_r(_1), _s_y_s_l_o_g_d(_8)
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BUGS
Under 2.11BSD the logfile /usr/adm/messages is used if a non
networking kernel has been booted. That file must be publi-
cally writeable in this case.
HISTORY
These functions appeared in 4.2BSD.
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