LPI BSD Specialist key terms

A partition table format used on BSD systems, especially FreeBSD and OpenBSD, stored in a disk sector near the start of the device. It defines named slices and their sizes and types.

A BSD term for a primary partition entry inside a disk label, numbered 1 through 4 on FreeBSD. A slice can be further divided into partitions or used directly as a filesystem.

GUID Partition Table, the modern partition scheme that replaces MBR on large disks. BSD tools such as gpart and installers create GPT entries and may still use BSD labels inside them.

A FreeBSD command for creating, modifying, and inspecting partition tables, including GPT and MBR schemes. Subcommands such as create, add, show, and destroy operate on named schemes and entries.

A BSD utility that builds a new filesystem on a device or partition, typically UFS. It writes superblock and cylinder group metadata, erasing prior contents, so it is run only on intended targets.

The Unix File System, the traditional native filesystem on BSD systems. It stores data in blocks and inodes with superblock metadata, and variants add soft updates or journaling for crash consistency.

A technique that orders metadata writes so the on-disk filesystem stays consistent after a crash without full journaling. It is commonly enabled on UFS and reduces fsck repair work.

The filesystem consistency checker. It scans metadata such as inodes and block maps, reports inconsistencies, and can repair them interactively or automatically, usually at boot after an unclean shutdown.

A fixed-size metadata record on a Unix filesystem that describes one file: its type, permissions, owner, size, timestamps, link count, and pointers to data blocks. Names live in directories, not inodes.

The operation and command that attaches a filesystem on a device to a directory in the existing hierarchy. Options control read-only access, noexec, nosuid, and other behavior.

A configuration file, usually /etc/fstab, listing filesystems to mount at boot with their mount points, types, and options. Entries can be referenced by device name, label, or UUID.

Disk space used as virtual memory when RAM is full. BSD systems enable it with a swap partition or file configured in fstab or with tools such as swapon, and monitor it with swapinfo or top.

A combined filesystem and volume manager offering pooled storage, checksums, snapshots, clones, and RAID-like redundancy. It is native on FreeBSD and available on other BSDs, administered with zpool and zfs.

A ZFS storage pool built from one or more virtual devices such as disks, mirrors, or RAID-Z groups. Commands like zpool create, status, and scrub manage its health and layout.

A read-only point-in-time copy of a filesystem or ZFS dataset that consumes little space until data changes. Snapshots support fast rollback, backup, and cloning without copying all data.

A FreeBSD disk encryption framework that provides transparent encryption of block devices using providers attached to partitions. It supports keys stored in files or entered at boot.

The FreeBSD binary package manager. It installs, upgrades, and removes prebuilt packages, queries metadata, and resolves dependencies, using repositories configured in files under /etc/pkg.

The FreeBSD Ports Collection: a tree of makefiles and patches that builds software from source. Each port directory supports targets such as install, clean, and config for options.

The FreeBSD command that installs the pkg tool itself on a system that lacks it. It fetches the package manager from the configured repository before other packages can be installed.

A remote or local collection of package files and metadata that a package manager queries. FreeBSD pkg uses a configured URL and a signed catalog to resolve and download packages.

A FreeBSD pkg subcommand that checks installed packages against a vulnerability database and reports known security issues. It helps administrators decide which packages to update promptly.

The FreeBSD tool for fetching and applying binary security patches and minor version upgrades to the base system. It tracks release branches and can merge configuration file changes.

The main FreeBSD configuration file for system services and startup settings. Variables such as sshd_enable and ifconfig_em0 control which daemons and network interfaces start at boot.

A shell script in /etc/rc.d or /usr/local/etc/rc.d that starts, stops, or reports status of a service. It reads rc.conf variables and responds to arguments like start and stop.

A FreeBSD utility that safely reads and edits rc.conf variables from the command line. It validates names, avoids duplicates, and can target alternate configuration files.

A FreeBSD command that invokes an rc.d script with a given action, such as start, stop, restart, or status. It locates scripts in the standard rc directories.

A daemon that runs scheduled commands defined in crontab files. Each user can have a crontab with five time fields plus a command, and system-wide jobs live in /etc/crontab.

Both the file format and the command used to edit per-user scheduled jobs. The -e option edits, -l lists, and -r removes the current user's table, which cron then executes.

The system logging facility. A daemon such as syslogd receives messages from programs and the kernel and writes them to files or remote hosts according to rules in syslog.conf or newsyslog.

The FreeBSD framework that runs daily, weekly, and monthly maintenance scripts from /etc/periodic. Output is usually mailed to root, and scripts can be enabled or disabled individually.

A command that displays the kernel message buffer, showing hardware detection, device attachment, and boot-time errors. It is often the first place to look when a device is not recognized.

A command that configures and displays network interfaces, including addresses, netmasks, media settings, and link state. On BSD it also creates and destroys interface aliases and clones.

A command that displays and modifies the kernel routing table. Entries decide where packets go, and a default route sends traffic with no more specific match to a gateway.

A file listing DNS name servers and search domains used by the resolver library. It is usually written by DHCP clients or manually, and incorrect entries break name resolution.

A command that reports network statistics: active sockets, routing table entries, and interface counters. Options such as -r, -i, and -a select routing, interface, and socket details.

A FreeBSD command that lists open sockets and the processes owning them. It helps identify which daemon is listening on a port, similar in purpose to lsof for network sockets.

A directory entry that points to an existing inode, giving one file multiple names. Links share the same data and permissions, and the inode is freed only when the last link is removed.

A special file containing a path to another file or directory. Following it resolves to the target, and it can cross filesystems or dangle if the target is removed.

A command that changes file permission bits for owner, group, and others using octal or symbolic notation. It also sets special bits such as setuid, setgid, and sticky.

A value that masks permission bits when new files and directories are created. A typical umask of 022 yields files readable by all but writable only by their owner.

A command that changes the owner and optionally the group of files. Only root can generally give files to another user, and the -R option applies changes recursively.