Mixed Deck — All 010-160 Topics Flashcards

Under which circumstance does the GNU Affero GPL (AGPL) require source code disclosure that the regular GPL does not?

Answer: When the software is run as a network service accessible to users

The AGPL closes the 'ASP loophole' by requiring source disclosure when modified software is run as a network service, even without distributing binaries.

What does the acronym BIOS stand for?

Answer: Basic Input/Output System

BIOS stands for Basic Input/Output System, the firmware that initializes hardware during the boot process.

A new user is created with useradd. Where is their home directory placed by default?

Answer: /home/username

By default, useradd creates the home directory at /home/username unless overridden with the -d option.

Which command would you use to find out what type of shell you are currently running?

Answer: echo $SHELL

`echo $SHELL` prints the path to the current user's default shell (e.g., /bin/bash).

Which command shows the numeric (octal) permissions of a file?

Answer: stat file.txt

The stat command displays detailed file information including octal permissions.

What is the primary purpose of the `#!/bin/bash` line at the beginning of a shell script?

Answer: It specifies the absolute path to the interpreter that should execute the script.

This line, known as a 'shebang', is an interpreter directive. It tells the operating system's program loader which program (in this case, `/bin/bash`) should be used to run the commands contained in the script.

What is the role of udev in a Linux system?

Answer: Dynamically manage device nodes in /dev based on kernel events

udev listens for kernel uevent notifications and creates, removes, or renames device nodes in /dev accordingly.

What arithmetic value does `$(( 3 ** 2 ))` evaluate to in bash?

Answer: 9

The `**` operator performs exponentiation, so 3 to the power of 2 equals 9.

What compression format does the `xz` command produce by default?

Answer: .xz using LZMA2

The xz utility uses the LZMA2 algorithm and produces files with the .xz extension by default.

Which command substitution syntax stores the output of date into a variable TODAY?

Answer: TODAY=$(date)

$() performs command substitution, executing date and assigning its output to TODAY.

Which of the following commands is used to decompress a file that has a `.bz2` extension?

Answer: bunzip2

Files with a `.bz2` extension are compressed with the bzip2 algorithm. The corresponding command to decompress them is `bunzip2`. `gunzip` is for `.gz` files, `unzip` is for `.zip` files, and `unxz` is for `.xz` files.

Which of the following statements about the BSD 2-Clause license is correct?

Answer: It allows use in proprietary software with minimal restrictions

The BSD 2-Clause license is a permissive license that allows use in proprietary software, requiring only attribution and preservation of the license text.

A file is owned by user 'alice' and group 'staff'. The current user is 'bob', who is in the 'staff' group. The file permissions are rw-r--r--. Can bob write to the file?

Answer: No, bob can only read it via group permissions

The group permission is r-- (read-only), so bob, matched as a group member, can only read the file.

What does the command 'free -h' display?

Answer: RAM and swap memory usage in human-readable format

free -h displays RAM and swap memory statistics in human-readable format using units like MB and GB.

What is the purpose of the initramfs (initial RAM filesystem) during Linux boot?

Answer: Provide a temporary root filesystem before the real root is mounted

initramfs loads a temporary root filesystem into RAM so the kernel can mount the real root filesystem.

Which command removes an empty directory?

Answer: rmdir

`rmdir` removes empty directories; it fails if the directory contains any files.

Which `find` command option specifies the type of object to search for (file or directory)?

Answer: -type

`find -type f` finds regular files and `find -type d` finds directories, filtering results by object type.

What is the result of running: echo {a,b,c}.txt?

Answer: Prints: a.txt b.txt c.txt

Brace expansion generates the strings a.txt, b.txt, and c.txt, which echo then prints.

Which runlevel in traditional SysV init corresponds to multi-user mode with networking but without a graphical interface?

Answer: 3

Runlevel 3 is the standard multi-user networked text mode; runlevel 5 adds the graphical display manager.

User 'root' owns a file with permissions ----------. Can root read the file?

Answer: Yes, root bypasses permission checks

Root (UID 0) bypasses DAC permission checks and can read, write, and execute any file.