| | 1 | .\" Copyright (c) 1983 Regents of the University of California. |
| | 2 | .\" All rights reserved. The Berkeley software License Agreement |
| | 3 | .\" specifies the terms and conditions for redistribution. |
| | 4 | .\" |
| | 5 | .\" @(#)syslog.3 6.1 (Berkeley) %G% |
| | 6 | .\" |
| | 7 | .TH SYSLOG 3 "" |
| | 8 | .UC 5 |
| | 9 | .SH NAME |
| | 10 | syslog, openlog, closelog, setlogmask \- control system log |
| | 11 | .SH SYNOPSIS |
| | 12 | .B "#include <syslog.h> |
| | 13 | .PP |
| | 14 | .B "openlog(ident, logopt, maskpri) |
| | 15 | .br |
| | 16 | .B "char *ident; |
| | 17 | .PP |
| | 18 | .B "syslog(priority, message, parameters ... ) |
| | 19 | .br |
| | 20 | .B "char *message; |
| | 21 | .PP |
| | 22 | .B "closelog() |
| | 23 | .PP |
| | 24 | .B "setlogmask(maskpri) |
| | 25 | .SH DESCRIPTION |
| | 26 | .I Syslog |
| | 27 | arranges to write |
| | 28 | .I message |
| | 29 | onto the system log maintained by |
| | 30 | .IR syslogd (8). |
| | 31 | The message is tagged with |
| | 32 | .IR priority . |
| | 33 | The message looks like a |
| | 34 | .IR printf (3) |
| | 35 | string except that |
| | 36 | .B %m |
| | 37 | is replaced by the current error message (collected from |
| | 38 | .IR errno ). |
| | 39 | A trailing newline is added if needed. |
| | 40 | This message will be read by |
| | 41 | .IR syslogd (8) |
| | 42 | and written to the system console, log files, or forwarded to |
| | 43 | .I syslogd |
| | 44 | on another host as appropriate. |
| | 45 | If |
| | 46 | .I syslog |
| | 47 | cannot pass the message to |
| | 48 | .I syslogd |
| | 49 | and the message is priority LOG_FAIL or higher, |
| | 50 | it attempts to write the message on |
| | 51 | .IR /dev/console. |
| | 52 | .PP |
| | 53 | If special processing is needed, |
| | 54 | .I openlog |
| | 55 | can be called to initialize the log file. |
| | 56 | The parameter |
| | 57 | .I ident |
| | 58 | is a string that is prepended to every message. |
| | 59 | .I Logopt |
| | 60 | is a bit field indicating logging options. |
| | 61 | Current values for |
| | 62 | .I logopt |
| | 63 | are: |
| | 64 | .IP LOG_PID \w'LOG_ODELAY'u+3 |
| | 65 | log the process id with each message: |
| | 66 | useful for identifying instantiations of daemons. |
| | 67 | .IP LOG_CONS \w'LOG_ODELAY'u+3 |
| | 68 | Force writing error messages to the console if unable to send it to |
| | 69 | .I syslogd. |
| | 70 | This option is safe to use in daemon processes that have no controlling |
| | 71 | terminal since |
| | 72 | .I syslog |
| | 73 | will fork before opening the console. |
| | 74 | .IP LOG_ODELAY \w'LOG_ODELAY'u+3 |
| | 75 | Delay opening the connection to |
| | 76 | .I syslogd |
| | 77 | until the first error occurs. Useful for programs that need to manage the |
| | 78 | order in which file descriptors are allocated. |
| | 79 | .PP |
| | 80 | The |
| | 81 | .I maskpri |
| | 82 | parameter is a mask for screening out low priority messages. |
| | 83 | Calls to |
| | 84 | .I syslog |
| | 85 | with a priority whose corresponding bit in |
| | 86 | .I maskpri |
| | 87 | is not set are ignored. |
| | 88 | The default allows all priorities to be logged. |
| | 89 | .PP |
| | 90 | .I Closelog |
| | 91 | can be used to close the log file. |
| | 92 | .PP |
| | 93 | .I Setlogmask |
| | 94 | sets the log priority mask to |
| | 95 | .I maskpri |
| | 96 | and returns the previous mask. |
| | 97 | Priorities and masks of 0 are ignored. |
| | 98 | .SH EXAMPLES |
| | 99 | .nf |
| | 100 | syslog(LOG_SALERT, "who: internal error 23"); |
| | 101 | |
| | 102 | openlog("serverftp", LOG_PID, 0); |
| | 103 | syslog(LOG_INFO, "Connection from host %d", CallingHost); |
| | 104 | .fi |
| | 105 | .SH "SEE ALSO" |
| | 106 | syslogd(8) |
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