1.1 Summarize Linux Fundamentals Flashcards
/boot
stores boot loaders.
/proc
Stores system processes and resources.
/sys
System ( helps with interacting with Linux kernel; everything runs in RAM and deletes on shutdown).
/var
Stores files that grow in size like log files, databases for mail, etc.
/usr
User applications; non-essential user applications are stored here.
/lib
Libraries; files that binaries need to run certain application settings.
/dev
Devices; hardware, KBMs, harddrives.
/etc
Et cetera; all system-wide configuration files are here.
/opt
Optional; manually installed software from vendors and some repositories(like zeek or suricata).
/bin
Binaries; basic shell commands are stored here.
/sbin
System Binaries; Binaries that a system admin would use.
/home
All your personal files, documents, and downloads; user settings are also stored hidden files like .bashrc or .local.
/media
Flash Drives; removable devices and drives.
/mnt
mounted drives; permanent storage.
/root
Root user’s home folder.
/tmp
Stores system and user application data that is needed only temporarily.
mkinitrd command
generates RAM disk files, initrd.img and initramfs.img that the bootloader uses to load the system kernel.
grub2-install command
installs the grub2 configuration files to system.
grub2-mkconfig command
generates a new grub.cfg config file that can be used to update existing grub.cfg file.
grub2-update command
updates the grub2 configuration file.
dracut command
predecessor of mkinitrd command. It will generate a generic initramfs image
initrd.img
Archive file that contains all the essential files that are required for booting the OS.
vmlinuz
The vmlinuz file is found in the boot directory and contains kernel code and data required to start and manage the system.
GRUB2
Newer version of GRUB. It offers more control over the boot process, boot devices, and boot behavior.
The default bootloader today.
Preboot eXecution Environment (PXE)
Allows the client to retrieve required boot loaders and system files from a server over the network.
Kernel Panic
A critical error where the kernel has encountered an unrecoverable error. The system will halt and become unresponsive. This can happen because of bugs, hardware issues, bad drivers, filesystem corruption.
Block devices
read/write in blocks of data (hard drives, SSDs).
Character devices
Read/write in character streams of data (KBM, serial ports).
/dev/null
A special type of virtual device that discards anything you send or redirect into it.
/dev/zero
A special virtual device that returns a null character anytime you read from it.
Sends back the ASCII character of 0x00.
/dev/urandom
A special virtual device that returns a randomized series of pseudorandom numbers.
./configure script
It is a script that will compile a configuration for software based on your system.
make command
Once you make a configuration file with the ./configure script, this command will actually build the software from that configuration file.
make install command
After using the ./configure and make command to configure and build out the software, the make install command will install these binaries to their appropriate locations.
file storage
Organizes data into files and directories.
Block storage
Divides data into fixed-size blocks that are accessed by their unique addresses.
Object storage
Treats data as objects with unique identifiers, metadata, and content.
Master Boot Record(MBR)
The sector that the BIOS reads in and starts when the machine is first booted
GUID Partition Table (GPT)
Partition structure with a more modern design and is part of the UEFI standard.
Filesystem in Userspace(FUSE)
This lets non-privileged users create their own file systems without editing the underlying kernel code.
lspsi command
Displays info about devices connected to the system’s PCI/PCIE buses.
lsusb command
Used to list info about devices connected to usb.
-v flag —– device info
bus -s —— filter result
-d —- Vendor/product
dmidecode command
Dumps the system’s Desktop Management Interface table and presents it in a readable format.
