LSCPU(1)

💻 LSCPU(1) — the glow-up guide to your CPU 💅

okay bestie, welcome to lscpu, the user command that tells you literally everything about your CPU architecture. No cap, she's the main character of /proc. Let's go. 🦋

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✨ NAME ✨

lscpu — display information about the CPU architecture. That's it. That's the whole vibe. 🌸

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🎀 SYNOPSIS 🎀

lscpu [options]

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💖 DESCRIPTION 💖

So like, lscpu goes out and gathers CPU architecture info from sysfs, /proc/cpuinfo, and any applicable architecture-specific libraries (for example librtas on Powerpc). Then she curates it. The command output can be optimized either for parsing or for easy readability by humans — your choice, queen. 👑

The info she serves includes, for example, the number of CPUs, threads, cores, sockets, and Non-Uniform Memory Access (NUMA) nodes. She's also got the tea on CPU caches and cache sharing, family, model, bogoMIPS, byte order, stepping, and microcode version. All of it. Not gatekeeping a single crumb. 💅

Now, important: the default output formatting on a terminal is subject to change and may be optimized for better readability. The output for non-terminals (e.g., pipes) is never affected by this optimization and it is always in "Field: data\n" format. So if you want to see the default output without the optimizations, just do:

lscpu | less

Slay. Simple as that. ✨

In virtualized environments, the CPU architecture information displayed reflects the configuration of the guest operating system, which is typically different from the physical (host) system. On architectures that support retrieving physical topology information, lscpu also displays the number of physical sockets, chips, and cores in the host system. So like, she's showing you the guest's outfit, but she'll also tell you about the host's closet. 🫶

Options that produce an output table accept an optional list argument. This list is a comma-separated series of column labels to limit the table to only the specified columns, arranged in the specified order. Use --help to see a list of valid column labels. The labels are case insensitive. Not all columns are supported on all architectures. If an unsupported column is specified, lscpu prints the column but does not provide any data for it — it's giving "invited to the party but didn't show up." 💀

The cache sizes are reported as a summary from all CPUs. The versions before v2.34 reported per-core sizes, but this output was confusing due to complicated CPU topology and the way how caches are shared between CPUs. For more details about caches see --cache. Since version v2.37 lscpu follows cache IDs as provided by the Linux kernel and it does not always start from zero. Noted. 📝

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👑 OPTIONS 👑

• -a, --all — Include lines for online and offline CPUs in the output (this is the default for -e). Heads up though: this option may only be specified together with option -e or -p. She doesn't work alone, she's a duo act. 🎭
• -B, --bytes — Print sizes in bytes rather than in human-readable form. Raw numbers, no filter. By default, sizes are shown in units that are powers of 1024 bytes. The formal abbreviations for these units (KiB, MiB, GiB, ...) are further shortened to just their first letter: K, M, G, .... So cute, so concise. ✨
• -b, --online — Limit the output to online CPUs (default for -p). Same rule as above: this option may only be specified together with option -e or -p. 💫
• -C, --caches[=list] — Display details about CPU caches. For details about available information see the --list-columns output. If the list argument is omitted, all columns for which data is available are included in the command output. When specifying the list argument, the option string plus the equal sign (=) plus the list may not contain any whitespace. Examples: -C=NAME,ONE-SIZE or --caches=NAME,ONE-SIZE. The default list of columns may be extended if list is specified in the format +list (e.g., lscpu -C=+ALLOC-POLICY). 🍓
• -c, --offline — Limit the output to offline CPUs. You guessed it: this option may only be specified together with option -e or -p. 🙈
• -e, --extended[=list] — Display the CPU information in human-readable format. If the list argument is omitted, the default columns are included in the command output. The default output is subject to change — do not get attached, bestie. 😭 When specifying the list argument, the option string plus the equal sign (=) plus the list may not contain any whitespace. Examples: -e=cpu,node or --extended=cpu,node. The default list of columns may be extended if list is specified in the format +list (e.g., lscpu -e=+MHZ). 🔥
• -H, --list-columns — List the columns that can be specified with the --extended, --parse and --caches options. Can be used with --json or --raw to get the list in a machine-readable format. Machine-readable? She ate. 🤖✨
• --hierarchic[=when] — Use subsections in summary output. For backward compatibility, the default is to use subsections only when output is on a terminal, and to use flattened output on a non-terminal. The optional argument when can be never, always, or auto. If the when argument is omitted, it defaults to always. Structure? We love structure. 🏗️
• -J, --json — Use JSON output format for the default summary or extended output (see --extended). For backward compatibility, JSON output follows the default summary behavior for non-terminals (e.g., pipes) where subsections are missing. See also --hierarchic. Curly braces, my beloved. 🎀
• --output-all — Output all available columns. This option must be combined with either --extended, --parse, or --caches. Give me everything, I'm nosy. 👀
• -p, --parse[=list] — Optimize the command output for easy parsing. If the list argument is omitted, the command output is compatible with earlier versions of lscpu. In this compatible format, two commas are used to separate CPU cache columns. If no CPU caches are identified the cache column is omitted. If the list argument is used, cache columns are separated with a colon (:). When specifying the list argument, the option string plus the equal sign (=) plus the list may not contain any whitespace. Examples: -p=cpu,online,mhz or --parse=cpu,online,mhz. The default list of columns may be extended if list is specified in the format +list (e.g., lscpu -p=+MHZ). Scripts, this one's for you. 💜
• -r, --raw — Produce output in its raw format. This option is only applicable for the --extended, --parse, and --caches outputs. No seasoning, just the ingredients. 🧂
• -s, --sysroot directory — Gather CPU data for a Linux instance other than the instance from which the lscpu command is issued. The specified directory is the system root of the Linux instance to be inspected. Peeking into someone else's house, respectfully. 🏠
• -x, --hex — Use hexadecimal masks for CPU sets (for example "ff"). The default is to print the sets in list format (for example 0,1). Note that before version 2.30 the mask has been printed with 0x prefix. Throwback. 💀
• -y, --physical — Display physical IDs for all columns with topology elements (core, socket, etc.). Other than logical IDs, which are assigned by lscpu, physical IDs are platform-specific values that are provided by the kernel. Physical IDs are not necessarily unique and they might not be arranged sequentially. If the kernel could not retrieve a physical ID for an element, lscpu prints the dash (-) character. The CPU logical numbers are not affected by this option. So like, she's giving you the real-world address but the mailbox numbering is chaos. 🌀
• --arm-id[=list] — Print a list of the known ARM core implementers and their human readable names. If an argument is given, print a list of the individual core IDs and their names, for the given implementer. ARM girlies rise. 🌈
• --arm-model id — Print the name for this specific core model. This requires passing --arm-id=id to indicate the implementer id as well. Tag team, fr fr. 🤝
• --annotate[=when] — Adds an annotation to each column header name. Such an annotation can be shown as a tooltip by terminals that support this feature. The optional when argument can be always, never, or auto. If the argument is omitted, it defaults to auto, which means that annotations will only be used when the output goes to a terminal. Little hover secrets. ✨
• -h, --help — Display help text and exit. Our savior when we forget the flags. 🙏
• -V, --version — Display version and exit. 💫

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🌸 ENVIRONMENT 🌸

• LSCPU_COLUMNS= — Specifies a comma-separated list of output columns to print. All columns listed by --list-columns for the options -e and -p can be used. 🌱
• LSCPU_CACHES_COLUMNS= — Same as LSCPU_COLUMNS with the difference that columns only listed for the -C option can be used. Cache-specific, iykyk. 🍓
• LIBSMARTCOLS_DEBUG=all — enables libsmartcols debug output. 🐛
• LIBSMARTCOLS_DEBUG_PADDING=on — use visible padding characters. Now you can see the spacing. 👁️
• LIBSMARTCOLS_JSON=compact|lines — Controls JSON output format when using --json. Supported values are compact for JSON output with minimal whitespace, and lines for JSON Lines format (one JSON object per line). If unset or set to any other value, pretty-printed JSON is used. Aesthetic options, love that for us. 💅

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🧚 COLUMNS 🧚

A list of valid column labels can be viewed with the --list-columns option. Go look, she's not hiding anything. 🔍

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⭐ NOTES ⭐

The default output is subject to change. So whenever possible, you should avoid using default output in your scripts. Write it down, put it on your mirror, tattoo it. 📌

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💀 BUGS 💀

The basic overview of CPU models is based on heuristics, taking into account differences such as CPU model names and implementer IDs. In some (unusual) cases, CPUs may differentiate in flags or BogoMIPS, but these differences are ignored in the lscpu overview. So like, sometimes she's guessing a lil bit. 🫣

Sometimes in Xen Dom0 the kernel reports wrong data. Not her fault, blame the kernel. 😭

On virtual hardware the number of cores per socket, etc. can be wrong. Virtualization lies sometimes, bestie. 🎭

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💜 AUTHORS 💜

Cai Qian <qcai@redhat.com>, Karel Zak <kzak@redhat.com>, Heiko Carstens <heiko.carstens@de.ibm.com>, Christian Goeschel Ndjomouo <cgoesc2@wgu.edu>

Legends, all of them. 👑

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🔥 SEE ALSO 🔥

chcpu(8) — go read that one next, she's the sister. 🫶

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🐛 REPORTING BUGS 🐛

For bug reports, use the issue tracker <https://github.com/util-linux/util-linux/issues>. Tell them everything, they want the full tea. ☕

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🌈 AVAILABILITY 🌈

The lscpu command is part of the util-linux package which can be downloaded from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>. Go get her. 💖

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and that's the whole page, bestie!! this one shipped with util-linux 2.42.4, dated 2026-09-21 — so yeah, fresh off the press. now go run lscpu and flex your cores. mwah 💅✨🎀