unix check on learnings

What is the Unix systems characteristic called that refers to its modular design?

The Unix Philosophy

What is the set of simple tools provided by the Unix operating system?

coreutils or core utilities

What is the name of the GNU kernel?

GNU Hurd

Which shell is the POSIX shell synonymous with?

Bourne Shell

What is the default shell on GNU/Linux?

Bash/ Bourne again shell

True or False: The CLI, terminal, and shell are just different names for the same thing.

False

What is the root of the filesystem in Unix?

/ or a/

What is the name of the user that resides in kernel land?

root

What is the home directory of the root user?

/root

What is the administrator on a Linux system?

A user that is allowed to run commands as root, typically using the sudo command.

What is a device driver?

Device drivers let the OS know how to access and use information from that device, acting as a translator between device and application/OS.

What are the two types of device drivers?

Kernel-Mode Device Driver and User-Mode Device Driver

Where are log files kept in a Unix system?

/var/log

Where are system configuration files located in Unix?

/etc/

True or False: The /usr/bin directory contains required binaries.

False

What does the ~ symbol represent?

The home directory of the user.

What does a single dot (.) signify?

The current working directory.

Where does the absolute path for a file or directory start?

/

What is the fundamental interface between an application and the Linux kernel?

Syscalls

What is the command to list system calls by number on a Linux machine?

ausyscall –dump or ausyscall –dump | less

What is the name of the C library on GNU/Linux?

glibc

What is the file type for executable files in Unix/Linux?

elf

What does the mmap system call do?

Map files or devices into memory.

True or False: A reboot is required when one installs a Loadable Kernel Module (LKM)?

False

What command is used to list loaded kernel modules?

lsmod

What does the .ko file extension represent?

Kernel Object.

What are some common arguments used with the ps command?

UID - user ID, PID - process ID, PPID - parent process ID, C - CPU utilization percentage, TTY - terminal, TIME - elapsed CPU use time, CMD - command to start process.

What is a type of process that runs in the background without any human interaction?

Daemons.

What are the three types of login shells in Unix?

Login Shell, Interactive Shell, Non-Interactive Shell.

What shell actively reads commands from user input?

Interactive Shell.

What argument is used with the 'su' command to open a BASH login?

The Login Argument.

What argument opens a BASH login with the 'bash' command?

bash -l.

What is the restricted BASH shell called?

rBASH.

What command is used to print environmental variables?

printenv or env.

What environmental variable is checked when executing a command in the shell?

PATH.

What are the most notable applications of SSH?

Remote login and command line execution.

Name one file transfer protocol based on SSH.

SFTP.

What is an administrator account?

A regular user allowed to run commands as root with the command sudo.

What type of account do users like Apache have?

Service accounts.

What type of accounts belong to users like sys or a daemon?

System accounts.

What file contains user information in Linux?

/etc/passwd.

Where are user password hashes stored?

/etc/shadow.

Where are local user configurations stored?

~/.bashrc file.

What restricts the rights and access of a user to the minimal amount necessary to perform their role?

Principle of least privilege.

What element of user management states that administrators of a system should not share accounts?

Individual accounts.

What are some basics of password management?

Require password changes periodically, do not allow reuse of old passwords, and require passwords to have complexity.

What command is used to check network connectivity in Linux?

ping.

What command is used to display the routing table in Linux?

netstat.

What information do you need to configure an IP address?

IP Address, Gateway Address, Network Mask.

What are three command line tools used to interact with Networkd?

networkctl, nmtui, nmcli.

What does the 'd' after a process name (i.e., Networkd) stand for?

Daemon.

Samba’s functionality comes from which two protocols?

SMB and CIFS.

What does Samba do?

Provides file and print sharing between different Operating Systems.

Samba security modes are set in which file?

smb.conf.

What are the two security modes in Samba?

Share-level and User-level.

What protocol does LDAP sit on top of?

TCP/IP.

What are two common implementations of LDAP?

Active Directory (AD) for Windows and OpenLDAP for Linux.

The majority of Apache servers run on what system?

Linux.

Where is the index.html file located for Apache?

/var/www/html.

What are the symbols used to denote request and response headers?

What code signifies that everything worked correctly?

200 OK.

SystemV has run levels, what did SystemD migrate to?

Targets.

In SystemV Linux, what is the centralized configuration file?

inittab.

What is rsyslog?

Rocket fast syslog server.

What command is used for querying systemd for logs?

journalctl.

What command is used to edit the crontab?

crontab -e.

What does each field of the crontab represent?

MIN, HOUR, DOM (Day of month), MONTH, DOW (Day of Week), COMMAND.

What is the Debian package manager called?

apt.

A package in Linux is a container for what?

Metadata.