{ "content": [ { "type": "text", "text": "# units(7) (man)\n\n## TLDR\n\n> Convert between two units of measure.\n\n- Run in interactive mode:\n `units`\n- List all units containing a specific string in interactive mode:\n `search {{string}}`\n- Show the conversion between two simple units:\n `units {{quarts}} {{tablespoons}}`\n- Convert between units with quantities:\n `units \"{{15 pounds}}\" {{kilograms}}`\n- Show the conversion between two compound units:\n `units \"{{meters / second}}\" \"{{inches / hour}}\"`\n- Show the conversion between units with different dimensions:\n `units \"{{acres}}\" \"{{ft^2}}\"`\n- Show the conversion of byte multipliers:\n `units \"{{15 megabytes}}\" {{bytes}}`\n\n*Source: tldr-pages*\n\n---\n\n**Summary:** units - decimal and binary prefixes\n\n## Section Outline\n\n- **NAME** (2 lines)\n- **DESCRIPTION** (1 lines) — 3 subsections\n - Decimal prefixes (30 lines)\n - Binary prefixes (16 lines)\n - Discussion (25 lines)\n- **COLOPHON** (7 lines)\n\n## Full Content\n\n### NAME\n\nunits - decimal and binary prefixes\n\n### DESCRIPTION\n\n#### Decimal prefixes\n\nThe SI system of units uses prefixes that indicate powers of ten. A kilometer is 1000 meter,\nand a megawatt is 1000000 watt. Below the standard prefixes.\n\nPrefix Name Value\ny yocto 10^-24 = 0.000000000000000000000001\nz zepto 10^-21 = 0.000000000000000000001\na atto 10^-18 = 0.000000000000000001\nf femto 10^-15 = 0.000000000000001\np pico 10^-12 = 0.000000000001\nn nano 10^-9 = 0.000000001\nµ micro 10^-6 = 0.000001\nm milli 10^-3 = 0.001\nc centi 10^-2 = 0.01\nd deci 10^-1 = 0.1\nda deka 10^ 1 = 10\nh hecto 10^ 2 = 100\nk kilo 10^ 3 = 1000\nM mega 10^ 6 = 1000000\nG giga 10^ 9 = 1000000000\nT tera 10^12 = 1000000000000\nP peta 10^15 = 1000000000000000\nE exa 10^18 = 1000000000000000000\nZ zetta 10^21 = 1000000000000000000000\nY yotta 10^24 = 1000000000000000000000000\n\nThe symbol for micro is the Greek letter mu, often written u in an ASCII context where this\nGreek letter is not available. See also\n\n⟨http://physics.nist.gov/cuu/Units/prefixes.html⟩\n\n#### Binary prefixes\n\nThe binary prefixes resemble the decimal ones, but have an additional 'i' (and \"Ki\" starts\nwith a capital 'K'). The names are formed by taking the first syllable of the names of the\ndecimal prefix with roughly the same size, followed by \"bi\" for \"binary\".\n\nPrefix Name Value\nKi kibi 2^10 = 1024\nMi mebi 2^20 = 1048576\nGi gibi 2^30 = 1073741824\nTi tebi 2^40 = 1099511627776\nPi pebi 2^50 = 1125899906842624\nEi exbi 2^60 = 1152921504606846976\n\nSee also\n\n⟨http://physics.nist.gov/cuu/Units/binary.html⟩\n\n#### Discussion\n\nBefore these binary prefixes were introduced, it was fairly common to use k=1000 and K=1024,\njust like b=bit, B=byte. Unfortunately, the M is capital already, and cannot be capitalized\nto indicate binary-ness.\n\nAt first that didn't matter too much, since memory modules and disks came in sizes that were\npowers of two, so everyone knew that in such contexts \"kilobyte\" and \"megabyte\" meant 1024\nand 1048576 bytes, respectively. What originally was a sloppy use of the prefixes \"kilo\" and\n\"mega\" started to become regarded as the \"real true meaning\" when computers were involved.\nBut then disk technology changed, and disk sizes became arbitrary numbers. After a period of\nuncertainty all disk manufacturers settled on the standard, namely k=1000, M=1000 k,\nG=1000 M.\n\nThe situation was messy: in the 14k4 modems, k=1000; in the 1.44 MB diskettes, M=1024000; and\nso on. In 1998 the IEC approved the standard that defines the binary prefixes given above,\nenabling people to be precise and unambiguous.\n\nThus, today, MB = 1000000 B and MiB = 1048576 B.\n\nIn the free software world programs are slowly being changed to conform. When the Linux ker‐\nnel boots and says\n\nhda: 120064896 sectors (61473 MB) w/2048KiB Cache\n\nthe MB are megabytes and the KiB are kibibytes.\n\n### COLOPHON\n\nThis page is part of release 5.10 of the Linux man-pages project. A description of the\nproject, information about reporting bugs, and the latest version of this page, can be found\nat https://www.kernel.org/doc/man-pages/.\n\n\n\nLinux 2020-08-13 UNITS(7)\n\n" } ], "structuredContent": { "command": "units", "section": "7", "mode": "man", "summary": "units - decimal and binary prefixes", "synopsis": null, "tldr_summary": "Convert between two units of measure.", "tldr_examples": [ { "description": "Run in interactive mode", "command": "units" }, { "description": "List all units containing a specific string in interactive mode", "command": "search {{string}}" }, { "description": "Show the conversion between two simple units", "command": "units {{quarts}} {{tablespoons}}" }, { "description": "Convert between units with quantities", "command": "units \"{{15 pounds}}\" {{kilograms}}" }, { "description": "Show the conversion between two compound units", "command": "units \"{{meters / second}}\" \"{{inches / hour}}\"" }, { "description": "Show the conversion between units with different dimensions", "command": "units \"{{acres}}\" \"{{ft^2}}\"" }, { "description": "Show the conversion of byte multipliers", "command": "units \"{{15 megabytes}}\" {{bytes}}" } ], "tldr_source": "official", "flags": [], "examples": [], "see_also": [], "section_outline": [ { "name": "NAME", "lines": 2, "subsections": [] }, { "name": "DESCRIPTION", "lines": 1, "subsections": [ { "name": "Decimal prefixes", "lines": 30 }, { "name": "Binary prefixes", "lines": 16 }, { "name": "Discussion", "lines": 25 } ] }, { "name": "COLOPHON", "lines": 7, "subsections": [] } ] } }