The system clock held in the Linux kernel refers to the computer's hardware clock at boot time, but after that it runs separately and deviates. You can display the system clock with the *** date *** command. You can modify the system clock with *** date [MMDDhhmm [[CC] YY] [.ss]] *** and reflect it in the hardware clock with the *** hwclock *** command.
Software that acquires and processes system logs includes rsyslog and syslog-ng. Describe them in the following format in the .etc / rsyslog.conf file. Since the logs are only added, the rotation function (rotation function ( Use (list the settings in /etc/logrotate.conf).
Format *** [Facility]. [Priority] [Output] *** Facilities and priorities are collectively called selector fields. Facilities: daemon, kern, mail, etc. [] can be specified. Priority: If set low, the number of log outputs will decrease. (Emerge ⇒ alert ⇒ crit ⇒ err ⇒ warning ⇒ notice ⇒ info ⇒ debug ⇒ none) Output destination: / var / log / message (output to log file), [](output to terminals of all logged-in users)
There are several types of software that handle e-mail, such as MTA (Message Transfer Agent), so you can find out by checking port 25. Syntax *** netstat -atnp | grep 25 ***
[root@www /]# netstat -atnp | grep 25 tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 2014/master
Many Linux distributions use the Printing Subsystem (CUPS). Features include (1) IPP (InternetPrintingSystem, a protocol that supports printers on the network), (2) PPD (PostScriptPrinterDescription, Adobe PPD format file and device driver). Can be set) and so on. To print, first *** lpr [option] [file name] ***: The file specified by the option (-# number of copies, -P printer name) is sent to the print queue and processed in order. * ** lpq [Option] [User name] [Job number] ***: The contents of the print queue can be displayed with the option (-P printer name). *** lprm [Option] [Job number] ***: You can delete all jobs in the print queue with the option (-P printer name,-).
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