User:Hess0060

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Printer Administration Common UNIX Printing System (CUPS) is a printing system used by Linux computers. Information that will be sent to a printer is called a print job. The lp command is used to specify and print the print job. To check the status of a printer(s) the lpstat command is used. The cups daemon (cupsd) will assign all print jobs a unique print job ID and put them in the print queue. The print queue is a special temporary directory where the print jobs are stored before being sent to the printer. The path of the queue is usually /var/spool/cups on most Linux systems. If the printer is accepting print jobs, the cupsd will put the print job in to the queue. This is called spooling or queuing. Adding the –t option shows all the printers and there statuses on the system. kevin@kubuntu1:~$ lpstat -t scheduler is running system default destination: Samsung-ML-2152W device for Samsung-ML-2152W: smb:///192.168.0.195 Samsung-ML-2152W accepting requests since Tue 17 Jan 2012 11:25:40 PM CST printer Samsung-ML-2152W is idle. enabled since Tue 17 Jan 2012 11:25:40 PM CST kevin@kubuntu1:~$ To manipulate the status of a printer by using the cupsaccept, cupsreject, cupsenable, or cupsdisable commands. kevin@kubuntu1:~$ cupsaccept Samsung-ML-2152W kevin@kubuntu1:~$ cupsdisable Samsung-ML-2152W kevin@kubuntu1:~$ lpstat -t scheduler is running system default destination: Samsung-ML-2152W device for Samsung-ML-2152W: smb:///192.168.0.195 Samsung-ML-2152W accepting requests since Fri 23 Mar 2012 11:35:18 AM CDT printer Samsung-ML-2152W disabled since Fri 23 Mar 2012 11:35:18 AM CDT - Paused kevin@kubuntu1:~$ The –r option is used to give a reason why the printer’s status is set as such. kevin@kubuntu1:~$ cupsdisable Samsung-ML-2152W -r "OMG the printer is on fire" Samsung-ML-2152W kevin@kubuntu1:~$ lpstat -t scheduler is running system default destination: Samsung-ML-2152W device for Samsung-ML-2152W: smb:///192.168.0.195 Samsung-ML-2152W accepting requests since Fri 23 Mar 2012 11:35:18 AM CDT printer Samsung-ML-2152W disabled since Fri 23 Mar 2012 11:35:18 AM CDT - OMG the printer is on fire kevin@kubuntu1:/$ Use the lp command to print. kevin@kubuntu1:/$ lp -d Samsung-ML-2152W /home/kevin/Documents/reports request id is Samsung-ML-2152W-2 (1 file(s)) kevin@kubuntu1:/$ Other options can be added to the lp command as shown. Option Description −d printername Specifies the name of the printer to send the print job to −i print job ID Specifies a certain print job ID to modify −n number Prints a certain number of copies, where number can be any 

          number

−m Mails you confirmation of print job completion −o option Specifies certain printing options. Common printing 

          options include the following:
         cpi=number—Specifies the number of characters per inch,
          where number is the number of characters
         landscape—Prints in landscape orientation
          number-up=number—Prints the number of pages on a single
           page, where number is 1, 2, or 4
          sides=string—Sets double-sided printing, where string is
           either ”two-sided-short-edge” or ”two-sided-long-edge”

To print a list of all users logged in, pipe the who command to the lp command. kevin@kubuntu1:/$ who | lp -d Samsung-ML-2152W request id is Samsung-ML-2152W-4 (0 file(s)) kevin@kubuntu1:/$ To remove all print jobs from a specific user, add the –u <username> before the cancel command. To remove all print jobs use the –a as shown. kevin@kubuntu1:/$ cancel -a kevin@kubuntu1:/$ lpstat kevin@kubuntu1:/$ The Line Printer Daemon (LPD) is an alternative to CUPS, that is used by older Linux systems. The LPD commands can be used in CUPS. LPR command = print documents LPC command = view printer status LPQ command = see jobs in the queue LPRM command = remove job form queue You can find the cupsd configuration file in the /etc/cups/cupsd.conf directory. The /etc/cups/printers.conf contains settings about the specific printer. The command system-config-printer will launch a GUI-based program; the Printer Configuration tool. This program lets you add printers with Plug and Play (PnP) or specify the Uniform Resource Identifier (URI). Hewlett-Packard JetDirect, Internet Printing Protocol (IPP), Line Printer Daemon (LPD or Windows (SAMBA) allows you to print to a printer across the network. From the Printer Configuration tool you are also able to give users and groups permission to print to specific printers. You can use CUPS to administer and remotely administer printes through a web browser. To open the CUPS web-based control panel, navigate to http://servername:631.

Log File Administration

  • For identifying and troubleshooting problems on a Linux System
  • Called log files most Daemons record information and error messages to files stored on the file system.
  • Typically stored in the /var/log directory
  • Example:
  • /var/log/samba contains log files created by the samba file-sharing daemons

Common Linux log files found in /var/log

  • boot.log
  • Contains basic information regarding daemon startup obtained during system initialization
  • cron
  • Contains information and error messages generated by the cron and at daemons
  • dmesg
  • Contains detected hardware information obtained during system startup
  • maillog
  • Contains information and error messages generated by the sendmail daemon
  • secure
  • Contains information and error messages regarding network access generated by daemons such as sshd and xinetd
  • wtmp
  • Contains a history of all login sessions
  • rpmpkgs yum.log
  • Contains a list of packages installed by the Red Hat Package Manager and related error messages
  • xferlog
  • Contains information and error messages generated by the FTP daemon
  • Xorg.0.log XFree86
  • Contains information and error messages generated by X Windows
  • lastlog
  • Contains a list of users and their last login time; must be viewed using the lastlog command
  • messages
  • Contains detailed information regarding daemon startup obtained at system initialization as well as important system messages produced after system initialization

System Log Daemon

  • logging of most events is handled centrally in Linux in the System Log Deamon
  • When the daemon is started on the system
  • Creates a socket /dev/log
  • This is for other system processes to write to
  • It then reads any information written to this socket and saves it to the appropriate log file according to /etc/rsyslog.conf
  • To view use cat /etc/rsyslog.conf
  • Sample output showing the Facility, Priority and Location of the /etc/rsyslog.conf file
  • news.=crit /var/log/news/news.crit
  • Facility: "news."
  • The area of the system to listen to and log
  • Priority: "=crit"
  • The importance of the information being logged
  • Location: /var/log/news/news.crit
  • The location and path of the log file


Examples of kernel log facilities with differing priorities

  • kern.warning /var/log/logfile
  • logs warning messages and those with more serious priorities to the /var/log/logfile
  • kern.=warning /var/log/logfile
  • logs just the warning messages to the /var/log/logfile
  • kern.* /var/log/logfile
  • logs all error messages to the /var/log/logfile
  • kern.*;kern. !=warn /var/log/logfile
  • logs all but the warning priority messages to /var/log/logfile
  • \*.=warn;kern.none /var/log/logfile
  • logs all warnings from all facilities except the kernel to the /var/log/logfile


Facilities used by the System Daemon Log

  • auth or security
  • Specifies messages from the login system, such as the login program, the getty program, and the su command
  • authpriv
  • Specifies messages from the login system when authenticating users across the network or to system databases
  • cron
  • Specifies messages from the cron and at daemons
  • daemon
  • Specifies messages from system daemons, such as the FTP daemon
  • kern
  • Specifies messages from the Linux kernel
  • lpr
  • Specifies messages from the printing system (lpd)
  • mail
  • Specifies messages from the e-mail system (sendmail)
  • mark
  • Specifies time stamps used by syslogd; used internally only
  • news
  • Specifies messages from the Inter Network News daemon and other USENET daemons
  • syslog
  • Specifies messages from the syslog daemon
  • user
  • Specifies messages from user processes
  • uucp
  • Specifies messages from the uucp (UNIX to UNIX copy) daemon
  • local0-7
  • Specifies local messages; these are not used by default but can be defined for custom use

Priorities used by the System Daemon Log (listed in ascending order)

  • debug
  • Indicates all information from a certain facility
  • info
  • Indicates normal information messages as a result of system operations
  • notice
  • Indicates information that should be noted for future reference, yet does not indicate a problem
  • warning or warn
  • Indicates messages that might be the result of an error but are not critical to system operations
  • error or err
  • Indicates all other error messages not described by other priorities
  • crit
  • Indicates system critical errors such as hard disk failure
  • alert
  • Indicates an error that should be rectified immediately, such as a corrupt system database
  • emerg or panic
  • Indicates very serious system conditions that would normally be broadcast to all users


The etc/rsyslog.conf file can also send logging information to another computer.

  • Facility.priority @hostname:portnumber
  • The remote computer
  • Must have modules that listen to TCP or UDP protocol uncommented in the /etc/rsyslog.conf
  • Commented
    1. Provides UDP syslog reception
    2. $ModLoad imudp.so
    3. $UDPServerRun 514
    4. Provides TCP syslog reception
    5. $ModLoad imtcp.so
    6. $InputTCPServerRun 514
  • Un-Commented
    1. Provides UDP syslog reception
  • $ModLoad imudp.so
  • $UDPServerRun 514
    1. Provides TCP syslog reception
  • $ModLoad imtcp.so
  • $InputTCPServerRun 514
  • This allows the system to accept incoming requests from another System Log Daemon on TCP and UDP port 514 (the default System Log Daemon port)



Managing Log Files

Log files can contain a lot of important system information so it's a good idea to clear the contents of the log files from time to time.

DO NOT remove the log files, the permissions and ownership will be removed as well!!!

We're just going to clear out the contents of the log file.

To do so the > redirect symbol can be used.

This function can be scheduled as well using the logrotate command to backup and clear logfiles stored in /etc/logrotate.conf file and files stored in /etc/logrotate.d directory

    • The log rotate command renames (rotates) log files on a cyclic basis
    • test.log becomes test.log.YYYYMMDD
    • A new test.log file is created to accept system log info.
  • Can be set to keep a certain number of log files
  • If configured to keep 2 log files, logrotate will only keep 2 copies. Then when it cycles logrotate will automatically remove the oldest copy.
  • Most rotation information within /etc/logrotate.conf is overridden from files stored in the /etc/logrotate.d directory.

On most Linux systems, the logrotate utility is automatically scheduled to run daily via the file /etc/cron.daily/logrotate, however it can be run manually by typing logrotate /etc/logrotate.conf at a command prompt

Over time the logrotate command generates several copies of each logfile /var/log to view this we type Ls /var/log

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