108 Essential System Services KT

Question 1

108.1 Maintain system time

Answer 1

The following is a partial list of the used files, terms and utilities:

/usr/share/zoneinfo/
/etc/timezone
/etc/localtime
/etc/ntp.conf
/etc/chrony.conf
date
hwclock
timedatectl
ntpd
ntpdate
chronyc
pool.ntp.org

Question 2

/usr/share/zoneinfo/

Answer 2

The system timezone database directory.

Question 3

/etc/timezone

Answer 3

The /etc/timezone file is a plain text file. It usually includes the continent and place, unless a more generic setting is used like UTC.

Question 4

/etc/localtime

Answer 4

The system timezone file.

Question 5

/etc/ntp.conf

Answer 5

The /etc/ntp.conf file is the primary configuration file for the ntpd service.

Question 6

/etc/chrony.conf

Answer 6

This is the location where the chrony.conf file is compiled. chrony.conf is the configuration file for the chronyd daemon.

Question 7

date

Answer 7

Command: Displays the system clock.

Question 8

hwclock

Answer 8

Command: hwclock is an administration tool for the time clocks.

hwclock [function] [option…]

Question 9

timedatectl

Answer 9

Command: Displays the system clock, UTC, and timezone information.

Question 10

ntpd

Answer 10

The Network Time Protocol daemon (ntpd) is a process that ensures the system clock is in sync with the time provided by remote NTP servers.

Question 11

ntpdate

Answer 11

Command: ntpdate sets the local date and time by polling the Network Time Protocol (NTP) server(s). Servers are given as arguments to determine the correct time. It must be run as root on the local host.

ntpdate [ -46bBdqsuv ]
[ -a key ] [ -e authdelay] 
[ -k keyfile ] [ -o version ] 
[ -p samples ] [ -t timeout ] 
[ -U user_name] server [ ... ]

Question 12

chronyc

Answer 12

Command: chronyc is a command-line interface program which can be used to monitor chronyd’s performance and to change various operating parateters whilst it is running.

chrony is a pair of programs for maintaining the accuracy of computer clocks.

chronyc [OPTIONS]

Question 13

pool.ntp.org

Answer 13

The pool.ntp.org address is a link to a cluster of NTP servers that are geographically spread throughout the world.

Question 14

108.2 System logging

Answer 14

Terms and Utilities:

/etc/rsyslog.conf
/var/log/
logger
logrotate
/etc/logrotate.conf
/etc/logrotate.d/
journalctl
systemd-cat
/etc/systemd/journald.conf
/var/log/journal/

Question 15

/etc/rsyslog.conf

Answer 15

The rsyslog.conf file is the main configuration file for the rsyslogd(8) which logs system messages on *nix systems.

Question 16

/var/log/

Answer 16

The /var/log/ directory is the standard location for log files to be placed by the syslogd daemon.

Question 17

logger

Answer 17

Command: logger makes entries in the system log.

logger [options] [message]

Question 18

logrotate

Answer 18

Command: logrotate is designed to ease administration of systems that generate large numbers of log files.

logrotate [–debug] [–verbose] [–log file] [–force] [–state file] [–mail command] config_file [config_file2 …]

Question 19

/etc/logrotate.conf

Answer 19

The /etc/logrotate.conf is the primary configuration file for the logrotate command.

Question 20

/etc/logrotate.d/

Answer 20

The /etc/logrotate.d/ directory stores application specific log settings.

Question 21

journalctl

Answer 21

Command: journalctl may be used to query the contents of the systemd(1) journal as written by systemd-journald.service(8).

journalctl [OPTIONS…] [MATCHES…]

Question 22

systemd-cat

Answer 22

Command: systemd-cat may be used to connect the standard input and output of a process to the journal.

systemd-cat [OPTIONS…] [COMMAND] [ARGUMENTS…]

Question 23

/etc/systemd/journald.conf

Answer 23

These files configure various parameters of the systemd journal service, systemd-journald.service(8).

Question 24

/var/log/journal/

Answer 24

The /var/log/journal/ directory is where systemd stores logs.

Question 25

108.3 Mail Transfer Agent (MTA) basics

Answer 25

Terms and Utilities: ``` ~/.forward sendmail emulation layer commands newaliases mail mailq postfix sendmail exim ```

Question 26

~/.forward

Answer 26

Email forwarding file. If this file exists, smtpd(8) forwards email to the destinations specified therein.

Question 27

sendmail emulation layer commands

Answer 27

These are backwards compatible commands that can be used with MTAs other than sendmail.

Question 28

newaliases

Answer 28

Command: The newaliases utility makes changes to the mail aliases file visible to smtpd(8). newaliases [-f file]

Question 29

mail

Answer 29

Command: mail is an intelligent mail processing system which has a command syntax reminiscent of ed(1) with lines replaced by messages. mail -words [-dEIinv ] [-a header ] [-b bcc-addr ] [-c cc-addr ] [-s subject ] to-addr ...

Question 30

mailq

Answer 30

Command: List the mail queue. Each entry shows the queue file ID, message size, arrival time, sender, and the recipients that still need to be delivered. mailq

Question 31

postfix

Answer 31

Postfix is a free and open-source mail transfer agent (MTA) that routes and delivers electronic mail.

Question 32

sendmail

Answer 32

Sendmail is a general purpose internetwork email routing facility that supports many kinds of mail-transfer and delivery methods.

Question 33

exim

Answer 33

Exim is a mail transfer agent (MTA) used on Unix-like operating systems.

Question 34

108.4 Manage printers and printing

Answer 34

The following is a partial list of the used files, terms and utilities: CUPS configuration files, tools and utilities /etc/cups/ lpd legacy interface (lpr, lprm, lpq)

Question 35

CUPS configuration files

Answer 35

The cups-files.conf file configures the files and directories used by the CUPS scheduler, cupsd(8). It is normally located in the /etc/cups directory.

Question 36

CUPS tools

Answer 36

The cupsctl(8) program is used to manage the printing system as a whole, including things like debug logging and printer sharing.

Question 37

CUPS utilities

Answer 37

The lpadmin(8) program is used to add, modify, or delete destinations, while the lpinfo(8) command is used to list the available printer drivers and backends.

Question 38

/etc/cups/

Answer 38

The /etc/cups/ directory holds all of the cups configuration files.

Question 39

lpd legacy interface

Answer 39

cups-lpd is the CUPS Line Printer Daemon ("LPD") mini-server that supports legacy client systems that use the LPD protocol.

Question 40

lpr

Answer 40

Command: lpr submits files for printing. lpr [ -E ] [ -H server[:port] ] [ -U username ] [ -P destination[/instance] ] [ -# num-copies [ -h ] [ -l ] [ -m ] [ -o option[=value] ] [ -p ] [ -q ] [ -r ] [ -C title ] [ -J title ] [ -T title ] [ file(s) ]

Question 41

lprm

Answer 41

Command: lprm cancels print jobs that have been queued for printing. lprm [ -E ] [ -U username ] [ -h server[:port] ] [ -P destination[/instance] ] [ - ] [ job-id(s) ]

Question 42

lpq

Answer 42

Command: lpq shows the current print queue status on the named printer. lpq [ -E ] [ -U username ] [ -h server[:port] ] [ -P destination[/instance] ] [ -a ] [ -l ] [ +interval ]