702-100 Linux Professional Institute BSD Specialist Questions and Answers

The /etc/newsyslog.conf file is the configuration file for the newsyslog command, which is used to rotate log files on BSD systems. The newsyslog command is typically run by cron at regular intervals to check if any log files need to be rotated based on the criteria specified in the /etc/newsyslog.conf file. The file contains a series of entries, one per line, that define the log file name, the owner and group, the mode, the count, the size, the when, the flags, and the pidfile for each log file. For example, the following entry in the /etc/newsyslog.conf file:

/var/log/messages root:wheel 644 7 * @T00 Z /var/run/syslog.pid

means that the /var/log/messages file is owned by root and belongs to the wheel group, has the mode 644, is rotated 7 times, has no size limit, is rotated at midnight every day, is compressed after rotation, and the process ID of syslogd is read from /var/run/syslog.pid and sent a signal to reopen the log file.

The other options are either invalid files or belong to other purposes. For example, /etc/logs.conf is not a valid file, /etc/rc.logd is a startup script for the log daemon, /etc/rc.d/syslogd is a startup script for the syslog daemon, and /etc/syslog.conf is the configuration file for the syslog daemon.

References:

• [newsyslog.conf] - FreeBSD newsyslog.conf(5) Manual Page
• [newsyslog] - FreeBSD newsyslog(8) Manual Page
• [Log File Rotation] - FreeBSD Handbook

The ports collection on FreeBSD is a package management system that allows users to install third-party software from source or binary packages. The ports collection is stored in the /usr/ports/ directory, which contains subdirectories for different categories of software, such as archivers, databases, editors, etc. Each subdirectory contains one or more ports, which are directories that contain the files needed to build and install the software. The /usr/ports/ directory can be updated with the portsnap command34

Binary packages are pre-compiled versions of the ports that can be installed with the pkg command. Binary packages are downloaded from the FreeBSD package repository,which is hosted at pkg.freebsd.org. The packages are installed in the /usr/local/ directory by default, and the information about the installed packages is stored in the /usr/local/pkg/ directory. The /usr/local/pkg/ directory contains files with the .db extension, which are SQLite databases that store the metadata of the packages. The pkg command can query and manipulate these databases56 References: 3: https://docs.freebsd.org/en/books/handbook/ports/  4: https://www.freebsd.org/ports/  5: https://docs.freebsd.org/en/books/handbook/pkgng-intro/  6: https://www.freebsd.org/cgi/man.cgi?query=pkg &sektion=8

The subnet mask 255.255.224.0 corresponds to the hexadecimal netmask 0xffffe000 shown in the output. This subnet mask indicates a subnet with 19 bits for the network portion and 13 bits for the host portion, allowing for a large number of hosts within the subnet.

References:

• BSD Specialist Exam 702 Objectives - Linux Professional Institute
• FreeBSD Handbook - Networking

The nice command is used to run a command with a modified scheduling priority, which affects how much CPU time the command receives. The priority can be specified by the -n option, which takes an integer value between -20 and 19, where lower values indicate higher priority. By default, the nice value is incremented by 10, which means the command runs with lower priority than normal. Only the superuser can specify a negative increment, which means the command runs with higher priority than normal. For example, the command nice -n 5 date runs the date command with a priority of 5, while the command nice -n -10 ls runs the ls command with a priority of -10, but only if the user is the superuser. The nice command is useful for running CPU-intensive commands that do not need to finish quickly, or for running commands that need more CPU time than normal. References:

• nice - FreeBSD, the manual page for the nice command on FreeBSD.
• HowTo: Use ps, kill, nice, and killall To Manage processes in FreeBSD and OS X Unix Operating System - nixCraft, a tutorial on how to use the nice command and other process management commands on FreeBSD and OS X.

The question mark (?) is a special character in regular expressions that modifies the preceding expression to match zero or one times. For example, the regular expression colou?r matches both color and colour, but not colouur or colr. The question mark is also used to make an expression non-greedy, meaning that it will match the shortest possible string instead of the longest. For example, the regular expression <.?> matches the first pair of angle brackets in a string, while <.> matches the entire string enclosed by the outermost pair of angle brackets. References:

• Regular expression - Wikipedia, section “Basic concepts”
• How to write Regular Expressions? - GeeksforGeeks, section “Special Characters”

The excerpt C is a valid if condition in the Bourne shell because it uses the correct syntax and operators for the test command. The syntax of the if statement in the Bourne shell is:

if test-commands; then consequent-commands; [elif more-test-commands; then more-consequents;] [else alternate-consequents;] fi

The test-commands are any commands that return a status of 0 (true) or non-zero (false). The test command is a common way to perform various tests on files, strings, and numbers. The test command has the following format:

test expression

The expression consists of one or more primaries, which are unary or binary operators that evaluate to true or false. The primaries can be combined with the following operators:

! expression: Logical NOT expression -a expression: Logical AND expression -o expression: Logical OR ( expression ): Parentheses for grouping

The excerpt C uses the test command with the following expression:

“$var” = “test”

This expression tests if the value of the variable $var is equal to the string “test”. The = operator is a string comparison operator that returns true if the strings are equal. The double quotes around the variable and the string are used to prevent word splitting and globbing by the shell. The spaces around the operator are also required by the test command.

The excerpt C also uses the correct syntax for the then and fi keywords, which mark the beginning and the end of the if statement. The then keyword must be on the same line as the test command, or on a new line after a semicolon. The fi keyword must be on a new line.

The other excerpts are invalid for various reasons:

• The excerpt A uses the && operator instead of the -a operator for logical AND. The && operator is a shell operator that executes the second command only if the first command succeeds. The test command does not recognize the && operator as a valid argument. The excerpt A also uses the != operator instead of the -ne operator for numeric comparison. The != operator is a string comparison operator that returns true if the strings are not equal. The -ne operator is a numeric comparison operator that returns true if the numbers are not equal.
• The excerpt B uses the [ [ construct instead of the test command. The [ [ construct is a shell keyword that performs conditional expressions similar to the test command, but with some extensions and differences. The [ [ construct is not part of the POSIX standard and is not supported by all shells. The Bourne shell does not support the [ [ construct, and will treat it as a command name. The excerpt B also uses the wrong syntax for the then keyword, which must be on a new line or after a semicolon.
• The excerpt D uses the wrong syntax for the test command, which requires a space after the opening bracket and before the closing bracket. The excerpt D also uses the wrong syntax for the fi keyword, which must be on a new line.

A /24 IPv4 prefix provides 256 IP addresses, which is the number of addresses in one octet (2^8). A /28 subnet has 16 IP addresses (2^4). To calculate how many /28 subnets can fit into a /24 prefix, divide the total number of addresses in the /24 prefix by the number of addresses in a /28 subnet: 256 / 16 = 16. However, since each subnet has network and broadcast addresses that cannot be used for hosts, the actual number of usable subnets is less. In practice, you can create 16 subnets, each with 14 usable IP addresses for hosts.

References:

• Subnet Cheat Sheet
• IP Subnet Calculator

The command cp SI 52 in the Bourne shell script copies the file named by the value of SI to the file named 52. The SI is a positional parameter that represents the first argument passed to the script when it is executed. Positional parameters are numbered from 1 to 9, and can be accessed by using the dollar sign $ followed by the number. For example, $1 is the first positional parameter, $2 is the second, and so on. Therefore, the SI in the script is equivalent to $1, and it represents the first argument passed to the script. The correct answer is D. A positional parameter. References:

• [Positional Parameters - FreeBSD]
• [Shell Scripting Tutorial - Positional Parameters]

The file /etc/hostname.em0 contains the configuration for the network interface em0 on an OpenBSD system. This file specifies the IP address, netmask, gateway, and other options for the interface. The file is read by the netstart script during boot or when the interface is restarted. The file name is derived from the interface name, which is usually based on the driver name and the device number. For example, em0 is the first interface using the em driver, which supports Intel PRO/1000 network adapters.

References:

• Networking | OpenBSD Handbook
• [hostname.if(5) - OpenBSD manual pages]

Compiling an application from source code allows for customization of the binary to a system’s particular needs, including optimization for specific hardware and enabling or disabling certain features. Pre-compiled binaries are quick and easy to install but they don’t allow for such customization.

References:

• Understand the difference between a pre-compiled binary and compiling from source

The find command is used to search for files and directories that match certain criteria. The - -type option specifies the type of file to look for, and the d argument means directories. The . argument means the current directory. Therefore, the command find - -type d searches for all directories within the current directory. The other options are either invalid or do not match the question. References: 1: https://www.comptia.org/training/books/a-core-1-220-1101-study-guide, page 301  2: https://www.howtogeek.com/771399/how-to-use-the-find-command-in-linux/, section “The Linux find Command”

The /etc/fstab file contains information about the file systems that are mounted automatically at boot time or by the mount command. The file has six fields separated by whitespace: device, mount point, file system type, mount options, dump frequency, and pass number. The correct answer is D because it specifies the device (/dev/cd0a), the mount point (/cdrom), the file system type (cd9660), the mount option (ro for read-only), and the dump frequency and pass number (both 0 for no backup or fsck). The other answers are incorrect because they either have the wrong syntax, the wrong order of fields, or the wrong file system type. References:

• BSD Specialist Exam 702 Objectives, Topic 715: Basic Unix Skills, 715.2 File and Directory Management
• FreeBSD Handbook, Chapter 3: FreeBSD Basics, 3.8.2 Mounting and Unmounting File Systems

The directories that contain start scripts for services on FreeBSD are /usr/rc.d/ and /usr/local/etc/rc.d/. The /usr/rc.d/ directory contains the system-provided scripts for the base system services, such as cron, sshd, syslogd, etc. The /usr/local/etc/rc.d/ directory contains the scripts for the additional services installed from ports or packages, such as apache, mysql, nginx, etc. These scripts follow the BSD rc.d framework, which allows for fine-grained control and customization of the startup process. The scripts are invoked by the main /etc/rc script, which sources the /etc/rc.conf file for configuration options

https://docs.freebsd.org/en/articles/rc-scripting/

The cron job syntax consists of five fields that specify the time and date of execution, followed by the command or script to run. The fields are: minute, hour, day of month, month, and day of week. Each field can have a specific value, a range, a list, a wildcard (), or a step value. The wildcard () means any possible value for that field. The option B sets the minute field to 0 and the hour field to *, which means the script will run at the 0th minute of every hour, regardless of the day, month, or weekday. This is equivalent to once per hour. The other options are either invalid syntax or do not match the desired frequency. For example, option A sets all fields to *, which means the script will run every minute of every hour of every day, month, and weekday. Option C sets the minute field to * and the hour field to 0, which means the script will run every minute of the 0th hour, or once per day at midnight. Option D has a typo (o instead of *) and option E sets the day of month field to o, which is not a valid value. References:

• crontab - FreeBSD crontab(5) Manual Page1
• Crontab Explained in Linux [With Examples] - Linux Handbook2

The file command is used to determine the type of data contained in a computer file. It performs a series of tests on the file and prints a description of the file type based on the first successful test. The file command can take one or more file names as its arguments. For example, file mybackup will display the file type of mybackup. The other options are not valid commands for finding the file type. References:

• file command in Linux with examples
• file (command) - Wikipedia
• Linux File Command