Module 3 - 04-1 Flashcards
Navigate the Linux file system
Define Bash
The default shell in most Linux distributions
Define Command
An instruction telling the computer to do something
A command in Bash:
What does “a dollar sign before the cursor” mean
This is your prompt to enter a new command
~$ (blinking square)
Define Argument
Specific information needed by a command
What is one thing that is really important in Linux?
All commands and arguments are case sensitive
What is a Linux command?
- A dollar sign ($) before the cursor
- The information that is output from the shell
- An instruction telling the computer to do something
- The default shell in most Linux distributions
A Linux command is an instruction telling the computer to do something.
What does FHS stand for?
Filesystem Hierarchy Standard (FHS)
Define FHS
The component of the Linux OS that organizes data.
This file system is a very important part of Linux because everything we do in Linux is considered a file somewhere in the system’s directory.
It defines how directories, directory contents, and other storage is organized in the operating system.
The FHS is a hierarchical system, and just like with a tree, everything grows and branches out from the root.
Define Root Directory
The highest-level directory in Linux
All subdirectories branch off the root directory. Subdirectories can continue branching out to as many levels as necessary.
How is the Root Directory designated in Linux?
It is designated by a single forward slash ( / )
How are forward slashes (/) used when describing the directory structure in Linux?
Forward slashes are used when tracing back through these branches to the root.
What does the Linux command “ pwd “ stand for?
Print Working Directory
What are Key commands for navigating the file system in Linux?
The following Linux commands can be used to navigate the file system:
- pwd
- ls
- cd
What does the command “ pwd “ display when executed?
It displays the current working directory (the directory you are currently in) in the terminal
This command is useful for confirming your location within the filesystem.
The output gives you the absolute path to this directory.
For example, if you’re in your home directory and your username is analyst, entering pwd returns /home/analyst.
What does the command “ whoami “ display when executed?
To learn what your username is, use the whoami command.
The whoami command returns the username of the current user.
For example, if your username is analyst, entering whoami returns analyst.
It’s useful when you want to quickly check which user is currently logged in, especially if you’re managing multiple user accounts or switching between users in a terminal session.
The whoami command returns the username of the current user who is executing the command, providing a simple way to identify the active user.
What does the Linux command “ ls “ stand for?
List
What does the command “ ls “ display when executed?
It displays the names of files and directories in the current directory.
The ls command is highly versatile, and you can combine various flags to control the output in many ways.
If you want to return the contents of a directory that’s not your current working directory, you can add an argument after ls with the absolute or relative file path to the desired directory.
For example, if you’re in the /home/analyst directory but want to list the contents of its projects subdirectory, you can enter ls /home/analyst/projects or just ls projects.
What does the Linux command “ cd “ stand for?
Change Directory
What does the command “ cd “ display when executed?
It is used to navigate between directories in the filesystem.
To navigate to a subdirectory of the current directory, you can add an argument after cd with the subdirectory name.
For example, if you’re in the /home/analyst directory and want to navigate to its projects subdirectory, you can enter cd projects.
You can also navigate to any specific directory by entering the absolute file path. For example, if you’re in /home/analyst/projects, entering cd /home/analyst/logs changes your current directory to /home/analyst/logs.
Pro Tip: You can use the relative file path and enter cd .. to go up one level in the file structure. For example, if the current directory is /home/analyst/projects, entering cd .. would change your working directory to /home/analyst.
What are Common commands for reading file content in Linux?
The following Linux commands are useful for reading file content:
* cat
* head
* tail
* less
What does the Linux command “ cat “ stand for?
Concatenate
What does the command “ cat “ display when executed?
It is used to display the contents of a file on the terminal.
It can also be used to concatenate (combine) multiple files.
So, cat is a versatile command that can be used for displaying, combining, and manipulating the contents of files.
To display the contents of a file using the “ cat “ command in Linux, what would the format be?
To display the contents of a file using the “ cat “ command in Linux, the format is as follows:
” cat filename.txt “
Example:
If you want to display the contents of a file named “ example.txt “, you would run:
” cat example.txt “
This will output the entire contents of example.txt to the terminal.
What does the Linux command “ head “ stand for?
Head of a file
What does the command “ head “ display when executed?
It is used to display the first few lines of a file, by default the first 10 lines.
This is helpful when you want to quickly view the beginning of a file without opening the entire file.
Pro Tip: If you want to change the number of lines returned by head, you can specify the number of lines by including -n. For example, if you only want to display the first five lines of the updates.txt file, enter head -n 5 updates.txt.
To display the contents of a file using the “ head “ command in Linux, what would the format be?
To display the contents of a file using the “ head “ command in Linux, the format is as follows:
” head filename.txt “
Example:
If you want to display the contents of a file named “ example.txt “, you would run:
” head example.txt “
This will output the first 10 lines of content of example.txt to the terminal.
What does the ls command do?
- It displays just the beginning of a file, by default 10 lines.
- It displays the names of files and directories in the current working directory.
- It prints the working directory to the screen.
- It displays the content of a file.
The ls command displays the names of files and directories in the current working directory.
Define File Path
The location of a file or directory
In the file path, the different levels of the hierarchy are separated by a forward slash ( / )
What are five (5) standard FHS directories?
1) /home
2) /bin
3) /etc
4) /tmp
5) /mnt
What does the “ /home “ standard FHS directory mean?
Each user in the system gets their own home directory.
In the Filesystem Hierarchy Standard (FHS) for Unix-like operating systems, the /home directory is intended to store user-specific files and directories. It is the location where individual users’ personal directories (or home directories) are created.
Key points about /home:
User directories: The /home directory contains subdirectories, each named after a user (e.g., /home/john, /home/alice), and these directories hold that user’s personal files, configurations, and settings.
User data storage: This is where regular users can store their data, such as documents, pictures, videos, etc. Configuration files for applications specific to the user (e.g., hidden files that begin with a dot, such as .bashrc, .profile). Files that belong to the system or root user are typically not stored here.
Configuration files: Each user’s home directory may also contain hidden files (starting with a dot, like .bashrc or .profile) that store configuration settings for various applications or the shell environment.
Separation of User Data: The /home directory helps keep user data separate from system files, which reside in other directories like /bin, /etc, and /usr. This structure makes it easier to manage user files, back them up, and also provide security and privacy for individual users.
What does “ bin “ stand for?
Binary
What does the “ /bin “ standard FHS directory mean?
This directory stands for “binary” and contains binary files and other executables. Executables are files that contain a series of commands a computer needs to follow to run programs and perform other functions.
In the Filesystem Hierarchy Standard (FHS), the /bin directory is essential for holding essential system binaries (programs or executable files) that are required for basic system functionality, especially in single-user mode or during system recovery. These binaries are needed for the system to boot, repair itself, and allow the administrator to interact with the system.
In summary, the /bin directory is a vital part of the system, containing basic command-line tools and binaries required to manage and troubleshoot the system, even in a minimal or recovery environment.
What does “ etc “ stand for?
Et Cetera
What does the “ /etc “ standard FHS directory mean?
This directory stores the system’s configuration files.
In the Filesystem Hierarchy Standard (FHS), the /etc directory is dedicated to system-wide configuration files and scripts that are essential for system management. These files control the behavior of both the operating system and its installed software.
The /etc directory is essential for managing system-wide settings and configurations in Unix-like operating systems. It holds files that define how the system operates, how services run, and how various software packages are configured. It is critical for system administrators to manage and maintain these files, as they directly influence the overall behavior and security of the system.
What does “ tmp “ stand for?
Temporary
What does the “ /tmp “ standard FHS directory mean?
This directory stores many temporary files. The /tmp directory is commonly used by attackers because anyone in the system can modify data in these files.
In the Filesystem Hierarchy Standard (FHS), the /tmp directory is designated for storing temporary files that are used by the system and applications during their operation. These files are typically created for short-term use and are not meant to persist beyond the session or specific task for which they were created.
The /tmp directory is a critical location for storing temporary files used by applications and the system, providing a space for short-term data storage. Files in /tmp are usually discarded after their use, helping to manage system resources and keep the filesystem clean.
What does “ mnt “ stand for?
Mount
What does the “ /mnt “ standard FHS directory mean?
This directory stands for “mount” and stores media, such as USB drives and hard drives.
In the Filesystem Hierarchy Standard (FHS), the /mnt directory is designated as a mount point for temporarily mounted filesystems. A mount point is a location in the filesystem where an additional filesystem (such as an external drive, network share, or another partition) is made accessible to the operating system and users.
The /mnt directory in the FHS is a standard location for temporarily mounting filesystems or external storage devices. It is used mainly for administrative purposes and for temporarily accessing filesystems such as USB drives, network shares, or CD/DVDs. Filesystems mounted under /mnt are generally not persistent and are intended for short-term use.
What does “ man hier “ stand for?
Manual Page (Manual Hierarchy)
What does the “ /mnt “ mean?
The command man hier refers to the manual page for the Filesystem Hierarchy Standard (FHS) in Unix-like operating systems. Specifically:
man: This is the command used to display the manual pages (help documentation) for various commands, programs, and system features in Unix-like systems.
hier: This is the topic of the manual page, which describes the hierarchy or structure of the filesystem, as defined by the Filesystem Hierarchy Standard (FHS).
When you run the command man hier, it shows the manual page detailing the standard directory structure used in Unix-like systems, including information on common directories like /bin, /etc, /home, /tmp, /var, etc., and their purpose according to the FHS.
Example:
Running the command:
”
bash
man hier
“
will give you a description of the directory structure of a Unix-like system, explaining the organization of directories and their standard contents according to the FHS.
In summary, man hier is a command that provides documentation on the structure and organization of directories in Unix-based systems, as specified by the Filesystem Hierarchy Standard (FHS).
When the path leads to a subdirectory below the user’s home directory, the user’s home directory can be represented with what symbol?
When the path leads to a subdirectory below the user’s home directory, the user’s home directory can be represented by the tilde ( ~ ) symbol.
For example, /home/analyst/logs can also be represented as ~/logs.
Define Absolute File Path
The full file path, which starts from the root.
For example, /home/analyst/projects is an absolute file path.
An absolute file path is a complete path that specifies the location of a file or directory in a filesystem, starting from the root directory (denoted by / in Unix-like systems such as Linux and macOS). It provides the exact location, with no reliance on the current working directory, meaning it points directly to the file or directory from the top of the filesystem hierarchy.
Key Characteristics of an Absolute File Path:
Starts from the Root: An absolute path always begins with the root directory (/), which is the top-most directory in the filesystem.
Complete Path: It provides the entire path, including all intermediate directories, to reach a specific file or folder.
Unambiguous: Since it starts from the root, the path is unambiguous and refers to a specific location on the system, regardless of the user’s current working directory.
Examples:
/home/user/Documents/file.txt: The absolute path to the file file.txt inside the Documents directory of the user user.
/usr/local/bin/command: Refers to the command executable file in the /usr/local/bin directory.
In summary, an absolute file path is a fully qualified path that begins from the root directory and defines the exact location of a file or directory in the system.
Define Relative File Path
The file path that starts from a user’s current directory.
Relative file paths can use a dot (.) to represent the current directory, or two dots (..) to represent the parent of the current directory. An example of a relative file path could be ../projects.
A relative file path is a path that specifies the location of a file or directory relative to the current working directory. It does not start from the root directory (unlike an absolute path) but instead describes the location in relation to where you currently are in the filesystem.
Key Characteristics of a Relative File Path:
Does Not Start from the Root: A relative path starts from the current working directory, so it does not begin with a / (root directory).
Context-Dependent: The meaning of a relative path depends on the user’s current location in the filesystem (the working directory).
Shorter and More Flexible: It is typically shorter than an absolute path because it avoids specifying the full filesystem hierarchy, making it convenient for navigating within directories without needing to refer to the entire path.
Examples:
Documents/file.txt : A relative path to the file.txt located in the Documents folder, assuming you’re currently in a directory where Documents is a subdirectory.
../file.txt : A relative path that refers to file.txt in the parent directory (denoted by ..).
./subfolder/file.txt : A relative path to file.txt inside the subfolder directory of the current directory, where . refers to the current directory.
A relative file path provides a way to locate a file or directory in relation to the current directory, making it shorter and context-sensitive compared to an absolute path, which provides the full, unambiguous location from the root directory.
What does the Linux command “ tail “ stand for?
Tail of a file
What does the command “ tail “ display when executed?
To display the contents of a file using the “ tail “ command in Linux, what would the format be?
To display the contents of a file using the “ head “ command in Linux, the format is as follows:
” tail filename.txt “
Example:
If you want to display the contents of a file named “ example.txt “, you would run:
” tail example.txt “
This will output the last 10 lines of content of example.txt to the terminal.
