LPIC-1 101-500 key terms

Modern firmware interface that replaces the legacy BIOS. It reads boot loaders from files on an EFI System Partition formatted with FAT, and records boot entries in non-volatile memory.

The first 512-byte sector of a BIOS-partitioned disk. It holds boot code plus a four-entry primary partition table, which limits usable disks to about 2 TiB.

GUID Partition Table: the partitioning scheme normally paired with UEFI. It stores primary and backup headers with checksums, allows 128 partitions by default, and supports disks larger than 2 TiB.

The default boot loader on most Linux distributions. It loads a kernel and initramfs from many filesystem types, reading its menu from /boot/grub/grub.cfg, usually generated by grub-mkconfig.

A small compressed archive loaded into memory by the boot loader alongside the kernel. It supplies drivers and scripts needed to locate and mount the real root filesystem.

A configuration file describing something systemd manages, such as a service, socket, mount, or timer. Units live in /usr/lib/systemd/system and can be overridden in /etc/systemd/system.

Command used to read the systemd journal, the binary log collecting kernel and service messages. It can filter by unit, boot, time, or priority, for example journalctl -u sshd -b.

Prints the kernel ring buffer, which records hardware detection, driver loading, and kernel errors during boot. On restricted systems reading it may require root or sudo.

Userspace device manager that receives kernel notifications when hardware appears or disappears and creates matching entries under /dev, applying rules stored in /etc/udev/rules.d.

Object file loaded into the running kernel to add a driver or feature without rebooting. It is managed with lsmod, modprobe, modinfo, and option files in /etc/modprobe.d.

Virtual filesystem mounted at /proc where the kernel exposes runtime information and tunables as files, such as /proc/cpuinfo, /proc/interrupts, and /proc/mounts.

Low-level Debian tool that installs, configures, removes, and queries individual .deb packages. It does not download files or resolve dependencies; higher-level tools do that.

Package front end used on Debian and Ubuntu. Commands such as apt-get and apt download packages from repositories listed in /etc/apt/sources.list, resolve dependencies, and track state with dpkg.

Both a package format and its low-level command on Red Hat style systems. It installs, erases, queries, and verifies individual .rpm files but leaves dependency resolution to other tools.

Package manager for RPM-based distributions and successor to yum. It reads repository metadata, resolves dependencies, and installs, updates, or removes packages; the yum command usually points to it.

A server or directory holding packages together with an index and signatures. Package managers download the index first, then fetch and verify packages from it.

The three default data channels every process inherits: standard input on file descriptor 0, standard output on file descriptor 1, and standard error on file descriptor 2.

Shell syntax that changes where a command's file descriptors point, for example > file for stdout, 2> file for errors, 2>&1 to merge the two, and < file for input.

The | operator that connects the standard output of one command to the standard input of the next, so commands can be chained together as filters.

Searches its input line by line and prints lines matching a regular expression. Useful options include -i for case-insensitivity, -v to invert the match, and -r to recurse through directories.

Stream editor that applies scripted edits, mainly substitutions such as s/old/new/g, to text as it passes through. With -i it rewrites files in place.

Pattern-action language for processing text. It splits each input line into fields ($1, $2, and so on) and runs rules that print reports or compute totals.

Walks directory trees and selects entries by name, type, size, owner, or modification time. Matches can be acted on with -exec or -delete, or simply printed.

Reads items from standard input and builds command lines from them, running the command as often as needed. It is commonly paired with find to avoid overly long argument lists.

Archiver that writes many files into one stream or archive file. -c creates, -x extracts, -t lists, and -f names the archive; compression is added separately with gzip, bzip2, or xz.

Compresses one file at a time into a .gz file and decompresses with -d, by default replacing the original file. It does not combine files, so it is normally used together with tar.

Copies standard input to standard output while also writing that same data to one or more named files, so output can be saved partway through a pipeline.

Sends a signal to a process chosen by PID or job number. SIGTERM (15) requests a clean exit, while SIGKILL (9) forces termination and cannot be caught or ignored.

A contiguous region of a disk defined in the partition table, holding a filesystem or swap area. It is created with tools such as fdisk, gdisk, or parted and named like /dev/sda1.

Command family that creates a fresh filesystem of a chosen type on a partition or logical volume, for example mkfs.ext4 or mkfs.xfs. Existing data on the target is destroyed.

The directory where a filesystem is attached into the single directory tree. While something is mounted there, any files previously stored in that directory are hidden.

Configuration file listing filesystems to mount at boot, one per line, giving the device or UUID, mount point, filesystem type, options, and dump and fsck order values.

A long identifier generated when a filesystem is created. Because it does not depend on device ordering or cabling, it is preferred over /dev/sdX names inside /etc/fstab.

A metadata record on ext-style filesystems holding a file's type, permissions, owner, timestamps, size, and data block locations. Filenames are stored separately in directory entries.

A directory entry that shares an inode with another name for the same file. Both names are equal, and the data is freed only when the last link is removed.

A separate file whose content is a path to another file or directory. The kernel resolves it on access, so it can cross filesystems and becomes dangling if the target disappears.

Disk area used to hold memory pages pushed out of RAM. It is prepared with mkswap, activated with swapon, and usually listed in /etc/fstab so it returns after a reboot.

Program that checks filesystems for inconsistencies and repairs them. It must run on an unmounted filesystem, and each type has its own checker, such as e2fsck for ext4.

A bit mask subtracted from the default permissions when a file (666) or directory (777) is created. A umask of 022 yields 644 for files and 755 for directories.

Filesystem Hierarchy Standard: the convention assigning purposes to directories, such as /etc for configuration, /var for changing data, /usr for shareable programs, and /home for user files.