Chapter 7 - Administrating the System Flashcards
Summarize methods of creating and modifying user accounts.
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Accounts can be created or modified with the help of tools designed for the purpose, such as useradd and usermod. Alternatively, you can directly edit the /etc/passwd and /etc/shadow files, which hold the account information.
Describe the function of groups in Linux.
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Linux groups enable security features to be applied to arbitrary groups of users. Each group holds an arbitrary collection of users and group permissions can be set on files, giving members the same access rights to the files.
Summarize how to configure system logging
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System logging is controlled via the /etc/syslog.conf file. Lines in this file describe what types of log data, generated by programs are sent to log files and to which log files the log messages should go.
Explain the purpose of the Skeleton files.
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Skeleton files provide a core set of configuration files that should be present in user’s home directories when those directories are created. They provide a starting point for users to modify their important shell and other configuration files.
Describe how log rotation is managed.
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Log rotation is controlled via the /etc/logrotate.conf file (which typically refers to files in /etc/logrotate.d). Entries in these files tell the system whether to rotate logs at fixed intervals or when they reach particular sizes. When a log rotates, its renamed ( and possibly compressed), a new log file is created and the oldest archived log file may be deleted.
Summarize how to review journal data.
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The systemd-journald service is responsible for journal message data. The daemon is controlled via the /etc/systemd/journal.conf configuration file. This journal message data can only be viewed using the journalctl utility. To view system journal data, you must either use superuser privileges or to be a member of the systemd-journal group. Users can view their own user journal data files. To view the entire current journal data files, simply use the journalctl command with no parameters. To parse out journal data, use the various filters available with the journal.ctl utility via parameter.
Explain the two types of clocks in x86 and x86-64 hardware.
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The hardware clock keeps time when the computer is powered down, but most programs don’t use it while the computer is running. Such programs refer to the software clock, which is set from the hardware clock when the computer boots.
Summarize the function of NTP.
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The Network Time Protocol (NTP) enables a computer to set its clock based on the time maintained by an NTP server system. NTP can function as a tiered protocol, enabling one system to function as a client to an NTP server and as a server to additional NTP clients. This structure enables a single highly accurate time source to to be used by anywhere from a few to (theoretically) billions of computers via a tiered system of links
Explain the difference between system and user cron jobs.
page 400.
System cron jobs are controlled from /etc/crontab, are created by root and may be run as any user (but most commonly as root.) System cron jobs are typically run at certain fixed times on an hourly, daily, weekly or monthly basis. User cron jobs may be created by any user (various security measures permitting) are run under the authority of the account with which they’re associated and may be run at just about any repeating interval desired.
Describe how to configure anacron jobs.
page 400
The anacron jobs are controlled from the /etc/anacrontab file. The file is checked to see when each listed job was last executed and it ensured that the designated time period between executions is followed. Time peridos are listed in number of days. No time period can be less than one day and therefore jobs needing to be run more than one time per day should not use anacron. Often, anacron itself is run from a system startup script or from a cron job.
