openlog()

#include <syslog.h >

void openlog(const char *ident, intoption, int facility)

openlog():

openloglets us specify an ident that is added to each logmessage. This is normally thename of the program (cron, inetd, etc.)

openlog函数改变你的日志消息的呈现方式

 ident:

anident that is added to each logmessage

加在日志消息的最前面,通常是程序名，指示哪一个程序正在创建这条消息

option:

LOG_CONS-Ifthe log message can't be sent to syslogd via the UNIX domain datagram, themessage is written to the console instead.(如果消息无法记录到日志文件里则发送消息到控制台)    

LOG_NDELAY-Openthe UNIX domain datagram socket to the syslogddaemon immediately; don't wait untilthe first message is logged. Normally, the socket is not opened until the firstmessage is logged.

LOG_NOWAIT-Do not wait for child processesthat might have been created in the process of logging the message. Thisprevents conflicts with applications that catch SIGCHLD, since the application mighthave retrieved the child's status by the time that syslog calls wait.

LOG_ODELAY-Delay the open of theconnection to the syslogddaemon until the first message is logged.

LOG_PERROR-Write the log message tostandard error in additionto sending it to syslogd. (Unavailable on Solaris.)

LOG_PID-Log the process ID with eachmessage. This is intended for daemons that forka child process to handledifferent requests (as compared to daemons, such as syslogd, that never

callfork)

facility:

       LOG_AUTH-authorization programs: login, su, getty, ...

       LOG_AUTHPRIV-same as LOG_AUTH, but logged to file with restrictedpermissions

       LOG_CRON-cronand at

       LOG_DAEMON-system daemons: inetd, routed,...

       LOG_FTP-the FTP daemon (ftpd)

       LOG_KERN-messages generated by the kernel

       LOG_LOCAL0~LOG_LOCAL7- reserved for local use

       LOG_LPR-line printer system: lpd, lpc, ...

       LOG_MAIL-the mail system

       LOG_NEWS-the Usenet network news system

       LOG_SYSLOG-the syslogddaemon itself

       LOG_USER-messages from other user processes (default)

       LOG_UUCP-the UUCP system