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MAN(1) Manual pager utils MAN(1) NAME man - an interface to the system reference manuals SYNOPSIS man [man options] [[section] page ...] ... man -k [apropos options] regexp ... man -K [man options] [section] term ... man -f [whatis options] page ... man -l [man options] file ... man -w|-W [man options] page ... DESCRIPTION man is the system's manual pager. Each page argument given to man is normally the name of a program, utility or function. The manual page associated with each of these arguments is then found and displayed. A section, if provided, will direct man to look only in that section of the manual. The default action is to search in all of the available sections following a pre-defined order (see DEFAULTS), and to show only the first page found, even if page exists in several sections. The table below shows the section numbers of the manual followed by the types of pages they contain. 1 Executable programs or shell commands 2 System calls (functions provided by the kernel) 3 Library calls (functions within program libraries) 4 Special files (usually found in /dev) 5 File formats and conventions, e.g. /etc/passwd 6 Games 7 Miscellaneous (including macro packages and conventions), e.g. man(7), groff(7), man-pages(7) 8 System administration commands (usually only for root) 9 Kernel routines [Non standard] A manual page consists of several sections. Conventional section names include NAME, SYNOPSIS, CONFIGURATION, DE- SCRIPTION, OPTIONS, EXIT STATUS, RETURN VALUE, ERRORS, ENVIRONMENT, FILES, VERSIONS, CONFORMING TO, NOTES, BUGS, EXAMPLE, AUTHORS, and SEE ALSO. The following conventions apply to the SYNOPSIS section and can be used as a guide in other sections. bold text type exactly as shown. italic text replace with appropriate argument. [-abc] any or all arguments within [ ] are optional. -a|-b options delimited by | cannot be used together. argument ... argument is repeatable. [expression] ... entire expression within [ ] is repeatable. Exact rendering may vary depending on the output device. For instance, man will usually not be able to render italics when running in a termi- nal, and will typically use underlined or coloured text instead. The command or function illustration is a pattern that should match all possible invocations. In some cases it is advisable to illustrate sev- eral exclusive invocations as is shown in the SYNOPSIS section of this manual page. EXAMPLES man ls Display the manual page for the item (program) ls. man man.7 Display the manual page for macro package man from section 7. (This is an alternative spelling of "man 7 man".) man 'man(7)' Display the manual page for macro package man from section 7. (This is another alternative spelling of "man 7 man". It may be more convenient when copying and pasting cross-references to manual pages. Note that the parentheses must normally be quoted to pro- tect them from the shell.) man -a intro Display, in succession, all of the available intro manual pages contained within the manual. It is possible to quit between suc- cessive displays or skip any of them. man -t bash | lpr -Pps Format the manual page for bash into the default troff or groff format and pipe it to the printer named ps. The default output for groff is usually PostScript. man --help should advise as to which processor is bound to the -t option. man -l -Tdvi ./foo.1x.gz > ./foo.1x.dvi This command will decompress and format the nroff source manual page ./foo.1x.gz into a device independent (dvi) file. The redi- rection is necessary as the -T flag causes output to be directed to stdout with no pager. The output could be viewed with a program such as xdvi or further processed into PostScript using a program such as dvips. man -k printf Search the short descriptions and manual page names for the keyword printf as regular expression. Print out any matches. Equivalent to apropos printf. man -f smail Lookup the manual pages referenced by smail and print out the short descriptions of any found. Equivalent to whatis smail. OVERVIEW Many options are available to man in order to give as much flexibility as possible to the user. Changes can be made to the search path, sec- tion order, output processor, and other behaviours and operations de- tailed below. If set, various environment variables are interrogated to determine the operation of man. It is possible to set the "catch-all" variable $MANOPT to any string in command line format, with the exception that any spaces used as part of an option's argument must be escaped (pre- ceded by a backslash). man will parse $MANOPT prior to parsing its own command line. Those options requiring an argument will be overridden by the same options found on the command line. To reset all of the op- tions set in $MANOPT, -D can be specified as the initial command line option. This will allow man to "forget" about the options specified in $MANOPT, although they must still have been valid. Manual pages are normally stored in nroff(1) format under a directory such as /usr/share/man. In some installations, there may also be pre- formatted cat pages to improve performance. See manpath(5) for details of where these files are stored. This package supports manual pages in multiple languages, controlled by your locale. If your system did not set this up for you automatically, then you may need to set $LC_MESSAGES, $LANG, or another system-depen- dent environment variable to indicate your preferred locale, usually specified in the POSIX format: <language>[_<territory>[.<character-set>[,<version>]]] If the desired page is available in your locale, it will be displayed in lieu of the standard (usually American English) page. If you find that the translations supplied with this package are not available in your native language and you would like to supply them, please contact the maintainer who will be coordinating such activity. Individual manual pages are normally written and maintained by the maintainers of the program, function, or other topic that they docu- ment, and are not included with this package. If you find that a man- ual page is missing or inadequate, please report that to the maintain- ers of the package in question. For information regarding other features and extensions available with this manual pager, please read the documents supplied with the package. DEFAULTS The order of sections to search may be overridden by the environment variable $MANSECT or by the SECTION directive in /etc/manpath.config. By default it is as follows: 1 n l 8 3 0 2 3posix 3pm 3perl 3am 5 4 9 6 7 The formatted manual page is displayed using a pager. This can be specified in a number of ways, or else will fall back to a default (see option -P for details). The filters are deciphered by a number of means. Firstly, the command line option -p or the environment variable $MANROFFSEQ is interrogated. If -p was not used and the environment variable was not set, the ini- tial line of the nroff file is parsed for a preprocessor string. To contain a valid preprocessor string, the first line must resemble '\" <string> where string can be any combination of letters described by option -p below. If none of the above methods provide any filter information, a default set is used. A formatting pipeline is formed from the filters and the primary for- matter (nroff or [tg]roff with -t) and executed. Alternatively, if an executable program mandb_nfmt (or mandb_tfmt with -t) exists in the man tree root, it is executed instead. It gets passed the manual source file, the preprocessor string, and optionally the device specified with -T or -E as arguments. OPTIONS Non-argument options that are duplicated either on the command line, in $MANOPT, or both, are not harmful. For options that require an argu- ment, each duplication will override the previous argument value. General options -C file, --config-file=file Use this user configuration file rather than the default of ~/.manpath. -d, --debug Print debugging information. -D, --default This option is normally issued as the very first option and re- sets man's behaviour to its default. Its use is to reset those options that may have been set in $MANOPT. Any options that follow -D will have their usual effect. --warnings[=warnings] Enable warnings from groff. This may be used to perform sanity checks on the source text of manual pages. warnings is a comma- separated list of warning names; if it is not supplied, the de- fault is "mac". See the "Warnings" node in info groff for a list of available warning names. Main modes of operation -f, --whatis Equivalent to whatis. Display a short description from the man- ual page, if available. See whatis(1) for details. -k, --apropos Equivalent to apropos. Search the short manual page descrip- tions for keywords and display any matches. See apropos(1) for details. -K, --global-apropos Search for text in all manual pages. This is a brute-force search, and is likely to take some time; if you can, you should specify a section to reduce the number of pages that need to be searched. Search terms may be simple strings (the default), or regular expressions if the --regex option is used. Note that this searches the sources of the manual pages, not the rendered text, and so may include false positives due to things like comments in source files. Searching the rendered text would be much slower. -l, --local-file Activate "local" mode. Format and display local manual files instead of searching through the system's manual collection. Each manual page argument will be interpreted as an nroff source file in the correct format. No cat file is produced. If '-' is listed as one of the arguments, input will be taken from stdin. When this option is not used, and man fails to find the page re- quired, before displaying the error message, it attempts to act as if this option was supplied, using the name as a filename and looking for an exact match. -w, --where, --path, --location Don't actually display the manual page, but do print the loca- tion of the source nroff file that would be formatted. If the -a option is also used, then print the locations of all source files that match the search criteria. -W, --where-cat, --location-cat Don't actually display the manual page, but do print the loca- tion of the preformatted cat file that would be displayed. If the -a option is also used, then print the locations of all pre- formatted cat files that match the search criteria. If -w and -W are both used, then print both source file and cat file separated by a space. If all of -w, -W, and -a are used, then do this for each possible match. -c, --catman This option is not for general use and should only be used by the catman program. -R encoding, --recode=encoding Instead of formatting the manual page in the usual way, output its source converted to the specified encoding. If you already know the encoding of the source file, you can also use man- conv(1) directly. However, this option allows you to convert several manual pages to a single encoding without having to ex- plicitly state the encoding of each, provided that they were al- ready installed in a structure similar to a manual page hierar- chy. Consider using man-recode(1) instead for converting multiple manual pages, since it has an interface designed for bulk con- version and so can be much faster. Finding manual pages -L locale, --locale=locale man will normally determine your current locale by a call to the C function setlocale(3) which interrogates various environment variables, possibly including $LC_MESSAGES and $LANG. To tempo- rarily override the determined value, use this option to supply a locale string directly to man. Note that it will not take ef- fect until the search for pages actually begins. Output such as the help message will always be displayed in the initially de- termined locale. -m system[,...], --systems=system[,...] If this system has access to other operating systems' manual pages, they can be accessed using this option. To search for a manual page from NewOS's manual page collection, use the option -m NewOS. The system specified can be a combination of comma delimited op- erating system names. To include a search of the native operat- ing system's manual pages, include the system name man in the argument string. This option will override the $SYSTEM environ- ment variable. -M path, --manpath=path Specify an alternate manpath to use. By default, man uses man- path derived code to determine the path to search. This option overrides the $MANPATH environment variable and causes option -m to be ignored. A path specified as a manpath must be the root of a manual page hierarchy structured into sections as described in the man-db manual (under "The manual page system"). To view manual pages outside such hierarchies, see the -l option. -S list, -s list, --sections=list The given list is a colon- or comma-separated list of sections, used to determine which manual sections to search and in what order. This option overrides the $MANSECT environment variable. (The -s spelling is for compatibility with System V.) -e sub-extension, --extension=sub-extension Some systems incorporate large packages of manual pages, such as those that accompany the Tcl package, into the main manual page hierarchy. To get around the problem of having two manual pages with the same name such as exit(3), the Tcl pages were usually all assigned to section l. As this is unfortunate, it is now possible to put the pages in the correct section, and to assign a specific "extension" to them, in this case, exit(3tcl). Under normal operation, man will display exit(3) in preference to exit(3tcl). To negotiate this situation and to avoid having to know which section the page you require resides in, it is now possible to give man a sub-extension string indicating which package the page must belong to. Using the above example, sup- plying the option -e tcl to man will restrict the search to pages having an extension of *tcl. -i, --ignore-case Ignore case when searching for manual pages. This is the de- fault. -I, --match-case Search for manual pages case-sensitively. --regex Show all pages with any part of either their names or their de- scriptions matching each page argument as a regular expression, as with apropos(1). Since there is usually no reasonable way to pick a "best" page when searching for a regular expression, this option implies -a. --wildcard Show all pages with any part of either their names or their de- scriptions matching each page argument using shell-style wild- cards, as with apropos(1) --wildcard. The page argument must match the entire name or description, or match on word bound- aries in the description. Since there is usually no reasonable way to pick a "best" page when searching for a wildcard, this option implies -a. --names-only If the --regex or --wildcard option is used, match only page names, not page descriptions, as with whatis(1). Otherwise, no effect. -a, --all By default, man will exit after displaying the most suitable manual page it finds. Using this option forces man to display all the manual pages with names that match the search criteria. -u, --update This option causes man to update its database caches of in- stalled manual pages. This is only needed in rare situations, and it is normally better to run mandb(8) instead. --no-subpages By default, man will try to interpret pairs of manual page names given on the command line as equivalent to a single manual page name containing a hyphen or an underscore. This supports the common pattern of programs that implement a number of subcom- mands, allowing them to provide manual pages for each that can be accessed using similar syntax as would be used to invoke the subcommands themselves. For example: $ man -aw git diff /usr/share/man/man1/git-diff.1.gz To disable this behaviour, use the --no-subpages option. $ man -aw --no-subpages git diff /usr/share/man/man1/git.1.gz /usr/share/man/man3/Git.3pm.gz /usr/share/man/man1/diff.1.gz Controlling formatted output -P pager, --pager=pager Specify which output pager to use. By default, man uses pager, falling back to cat if pager is not found or is not executable. This option overrides the $MANPAGER environment variable, which in turn overrides the $PAGER environment variable. It is not used in conjunction with -f or -k. The value may be a simple command name or a command with argu- ments, and may use shell quoting (backslashes, single quotes, or double quotes). It may not use pipes to connect multiple com- mands; if you need that, use a wrapper script, which may take the file to display either as an argument or on standard input. -r prompt, --prompt=prompt If a recent version of less is used as the pager, man will at- tempt to set its prompt and some sensible options. The default prompt looks like Manual page name(sec) line x where name denotes the manual page name, sec denotes the section it was found under and x the current line number. This is achieved by using the $LESS environment variable. Supplying -r with a string will override this default. The string may contain the text $MAN_PN which will be expanded to the name of the current manual page and its section name sur- rounded by "(" and ")". The string used to produce the default could be expressed as \ Manual\ page\ \$MAN_PN\ ?ltline\ %lt?L/%L.: byte\ %bB?s/%s..?\ (END):?pB\ %pB\\%.. (press h for help or q to quit) It is broken into three lines here for the sake of readability only. For its meaning see the less(1) manual page. The prompt string is first evaluated by the shell. All double quotes, back-quotes and backslashes in the prompt must be escaped by a preceding backslash. The prompt string may end in an escaped $ which may be followed by further options for less. By default man sets the -ix8 options. The $MANLESS environment variable described below may be used to set a default prompt string if none is supplied on the command line. -7, --ascii When viewing a pure ascii(7) manual page on a 7 bit terminal or terminal emulator, some characters may not display correctly when using the latin1(7) device description with GNU nroff. This option allows pure ascii manual pages to be displayed in ascii with the latin1 device. It will not translate any latin1 text. The following table shows the translations performed: some parts of it may only be displayed properly when using GNU nroff's latin1(7) device. Description Octal latin1 ascii continuation hy- 255 - - phen bullet (middle 267 o o dot) acute accent 264 ' ' multiplication 327 x x sign If the latin1 column displays correctly, your terminal may be set up for latin1 characters and this option is not necessary. If the latin1 and ascii columns are identical, you are reading this page using this option or man did not format this page us- ing the latin1 device description. If the latin1 column is missing or corrupt, you may need to view manual pages with this option. This option is ignored when using options -t, -H, -T, or -Z and may be useless for nroff other than GNU's. -E encoding, --encoding=encoding Generate output for a character encoding other than the default. For backward compatibility, encoding may be an nroff device such as ascii, latin1, or utf8 as well as a true character encoding such as UTF-8. --no-hyphenation, --nh Normally, nroff will automatically hyphenate text at line breaks even in words that do not contain hyphens, if it is necessary to do so to lay out words on a line without excessive spacing. This option disables automatic hyphenation, so words will only be hyphenated if they already contain hyphens. If you are writing a manual page and simply want to prevent nroff from hyphenating a word at an inappropriate point, do not use this option, but consult the nroff documentation instead; for instance, you can put "\%" inside a word to indicate that it may be hyphenated at that point, or put "\%" at the start of a word to prevent it from being hyphenated. --no-justification, --nj Normally, nroff will automatically justify text to both margins. This option disables full justification, leaving justified only to the left margin, sometimes called "ragged-right" text. If you are writing a manual page and simply want to prevent nroff from justifying certain paragraphs, do not use this op- tion, but consult the nroff documentation instead; for instance, you can use the ".na", ".nf", ".fi", and ".ad" requests to tem- porarily disable adjusting and filling. -p string, --preprocessor=string Specify the sequence of preprocessors to run before nroff or troff/groff. Not all installations will have a full set of pre- processors. Some of the preprocessors and the letters used to designate them are: eqn (e), grap (g), pic (p), tbl (t), vgrind (v), refer (r). This option overrides the $MANROFFSEQ environ- ment variable. zsoelim is always run as the very first pre- processor. -t, --troff Use groff -mandoc to format the manual page to stdout. This op- tion is not required in conjunction with -H, -T, or -Z. -T[device], --troff-device[=device] This option is used to change groff (or possibly troff's) output to be suitable for a device other than the default. It implies -t. Examples (provided with Groff-1.17) include dvi, latin1, ps, utf8, X75 and X100. -H[browser], --html[=browser] This option will cause groff to produce HTML output, and will display that output in a web browser. The choice of browser is determined by the optional browser argument if one is provided, by the $BROWSER environment variable, or by a compile-time de- fault if that is unset (usually lynx). This option implies -t, and will only work with GNU troff. -X[dpi], --gxditview[=dpi] This option displays the output of groff in a graphical window using the gxditview program. The dpi (dots per inch) may be 75, 75-12, 100, or 100-12, defaulting to 75; the -12 variants use a 12-point base font. This option implies -T with the X75, X75-12, X100, or X100-12 device respectively. -Z, --ditroff groff will run troff and then use an appropriate post-processor to produce output suitable for the chosen device. If groff -mandoc is groff, this option is passed to groff and will sup- press the use of a post-processor. It implies -t. Getting help -?, --help Print a help message and exit. --usage Print a short usage message and exit. -V, --version Display version information. EXIT STATUS 0 Successful program execution. 1 Usage, syntax or configuration file error. 2 Operational error. 3 A child process returned a non-zero exit status. 16 At least one of the pages/files/keywords didn't exist or wasn't matched. ENVIRONMENT MANPATH If $MANPATH is set, its value is used as the path to search for manual pages. See the SEARCH PATH section of manpath(5) for the default behav- iour and details of how this environment variable is handled. MANROFFOPT Every time man invokes the formatter (nroff, troff, or groff), it adds the contents of $MANROFFOPT to the formatter's command line. MANROFFSEQ If $MANROFFSEQ is set, its value is used to determine the set of preprocessors to pass each manual page through. The default preprocessor list is system dependent. MANSECT If $MANSECT is set, its value is a colon-delimited list of sec- tions and it is used to determine which manual sections to search and in what order. The default is "1 n l 8 3 0 2 3posix 3pm 3perl 3am 5 4 9 6 7", unless overridden by the SECTION di- rective in /etc/manpath.config. MANPAGER, PAGER If $MANPAGER or $PAGER is set ($MANPAGER is used in preference), its value is used as the name of the program used to display the manual page. By default, pager is used, falling back to cat if pager is not found or is not executable. The value may be a simple command name or a command with argu- ments, and may use shell quoting (backslashes, single quotes, or double quotes). It may not use pipes to connect multiple com- mands; if you need that, use a wrapper script, which may take the file to display either as an argument or on standard input. MANLESS If $MANLESS is set, its value will be used as the default prompt string for the less pager, as if it had been passed using the -r option (so any occurrences of the text $MAN_PN will be expanded in the same way). For example, if you want to set the prompt string unconditionally to "my prompt string", set $MANLESS to '-Psmy prompt string'. Using the -r option overrides this envi- ronment variable. BROWSER If $BROWSER is set, its value is a colon-delimited list of com- mands, each of which in turn is used to try to start a web browser for man --html. In each command, %s is replaced by a filename containing the HTML output from groff, %% is replaced by a single percent sign (%), and %c is replaced by a colon (:). SYSTEM If $SYSTEM is set, it will have the same effect as if it had been specified as the argument to the -m option. MANOPT If $MANOPT is set, it will be parsed prior to man's command line and is expected to be in a similar format. As all of the other man specific environment variables can be expressed as command line options, and are thus candidates for being included in $MANOPT it is expected that they will become obsolete. N.B. All spaces that should be interpreted as part of an option's ar- gument must be escaped. MANWIDTH If $MANWIDTH is set, its value is used as the line length for which manual pages should be formatted. If it is not set, man- ual pages will be formatted with a line length appropriate to the current terminal (using the value of $COLUMNS, and ioctl(2) if available, or falling back to 80 characters if neither is available). Cat pages will only be saved when the default for- matting can be used, that is when the terminal line length is between 66 and 80 characters. MAN_KEEP_FORMATTING Normally, when output is not being directed to a terminal (such as to a file or a pipe), formatting characters are discarded to make it easier to read the result without special tools. How- ever, if $MAN_KEEP_FORMATTING is set to any non-empty value, these formatting characters are retained. This may be useful for wrappers around man that can interpret formatting charac- ters. MAN_KEEP_STDERR Normally, when output is being directed to a terminal (usually to a pager), any error output from the command used to produce formatted versions of manual pages is discarded to avoid inter- fering with the pager's display. Programs such as groff often produce relatively minor error messages about typographical problems such as poor alignment, which are unsightly and gener- ally confusing when displayed along with the manual page. How- ever, some users want to see them anyway, so, if $MAN_KEEP_STDERR is set to any non-empty value, error output will be displayed as usual. MAN_DISABLE_SECCOMP On Linux, man normally confines subprocesses that handle un- trusted data using a seccomp(2) sandbox. This makes it safer to run complex parsing code over arbitrary manual pages. If this goes wrong for some reason unrelated to the content of the page being displayed, you can set $MAN_DISABLE_SECCOMP to any non- empty value to disable the sandbox. PIPELINE_DEBUG If the $PIPELINE_DEBUG environment variable is set to "1", then man will print debugging messages to standard error describing each subprocess it runs. LANG, LC_MESSAGES Depending on system and implementation, either or both of $LANG and $LC_MESSAGES will be interrogated for the current message locale. man will display its messages in that locale (if avail- able). See setlocale(3) for precise details. FILES /etc/manpath.config man-db configuration file. /usr/share/man A global manual page hierarchy. SEE ALSO apropos(1), groff(1), less(1), manpath(1), nroff(1), troff(1), whatis(1), zsoelim(1), manpath(5), man(7), catman(8), mandb(8) Documentation for some packages may be available in other formats, such as info(1) or HTML. HISTORY 1990, 1991 - Originally written by John W. Eaton (jwe AT che.edu). Dec 23 1992: Rik Faith (faith AT cs.edu) applied bug fixes supplied by Willem Kasdorp (wkasdo AT nikhefk.nl). 30th April 1994 - 23rd February 2000: Wilf. (G.Wilford AT ee.uk) has been developing and maintaining this package with the help of a few dedicated people. 30th October 1996 - 30th March 2001: Fabrizio Polacco <fpolacco@de- bian.org> maintained and enhanced this package for the Debian project, with the help of all the community. 31st March 2001 - present day: Colin Watson <cjwatson AT debian.org> is now developing and maintaining man-db. BUGS https://gitlab.com/cjwatson/man-db/-/issues https://savannah.nongnu.org/bugs/?group=man-db 2.10.2 2022-03-17 MAN(1) MAN(7) Linux Programmer's Manual MAN(7) NAME man - macros to format man pages SYNOPSIS groff -Tascii -man file ... groff -Tps -man file ... man [section] title DESCRIPTION This manual page explains the groff an.tmac macro package (often called the man macro package). This macro package should be used by develop- ers when writing or porting man pages for Linux. It is fairly compati- ble with other versions of this macro package, so porting man pages should not be a major problem (exceptions include the NET-2 BSD re- lease, which uses a totally different macro package called mdoc; see mdoc(7)). Note that NET-2 BSD mdoc man pages can be used with groff simply by specifying the -mdoc option instead of the -man option. Using the -mandoc option is, however, recommended, since this will automatically detect which macro package is in use. For conventions that should be employed when writing man pages for the Linux man-pages package, see man-pages(7). Title line The first command in a man page (after comment lines, that is, lines that start with .\") should be .TH title section date source manual For details of the arguments that should be supplied to the TH command, see man-pages(7). Note that BSD mdoc-formatted pages begin with the Dd command, not the TH command. Sections Sections are started with .SH followed by the heading name. The only mandatory heading is NAME, which should be the first section and be followed on the next line by a one-line description of the pro- gram: .SH NAME item \- description It is extremely important that this format is followed, and that there is a backslash before the single dash which follows the item name. This syntax is used by the mandb(8) program to create a database of short descriptions for the whatis(1) and apropos(1) commands. (See lexgrog(1) for further details on the syntax of the NAME section.) For a list of other sections that might appear in a manual page, see man-pages(7). Fonts The commands to select the type face are: .B Bold .BI Bold alternating with italics (especially useful for function spec- ifications) .BR Bold alternating with Roman (especially useful for referring to other manual pages) .I Italics .IB Italics alternating with bold .IR Italics alternating with Roman .RB Roman alternating with bold .RI Roman alternating with italics .SB Small alternating with bold .SM Small (useful for acronyms) Traditionally, each command can have up to six arguments, but the GNU implementation removes this limitation (you might still want to limit yourself to 6 arguments for portability's sake). Arguments are delim- ited by spaces. Double quotes can be used to specify an argument which contains spaces. For the macros that produce alternating type faces, the arguments will be printed next to each other without intervening spaces, so that the .BR command can be used to specify a word in bold followed by a mark of punctuation in Roman. If no arguments are given, the command is applied to the following line of text. Other macros and strings Below are other relevant macros and predefined strings. Unless noted otherwise, all macros cause a break (end the current line of text). Many of these macros set or use the "prevailing indent." The "prevail- ing indent" value is set by any macro with the parameter i below; macros may omit i in which case the current prevailing indent will be used. As a result, successive indented paragraphs can use the same in- dent without respecifying the indent value. A normal (nonindented) paragraph resets the prevailing indent value to its default value (0.5 inches). By default, a given indent is measured in ens; try to use ens or ems as units for indents, since these will automatically adjust to font size changes. The other key macro definitions are: Normal paragraphs .LP Same as .PP (begin a new paragraph). .P Same as .PP (begin a new paragraph). .PP Begin a new paragraph and reset prevailing indent. Relative margin indent .RS i Start relative margin indent: moves the left margin i to the right (if i is omitted, the prevailing indent value is used). A new prevailing indent is set to 0.5 inches. As a result, all following paragraph(s) will be indented until the corre- sponding .RE. .RE End relative margin indent and restores the previous value of the prevailing indent. Indented paragraph macros .HP i Begin paragraph with a hanging indent (the first line of the paragraph is at the left margin of normal paragraphs, and the rest of the paragraph's lines are indented). .IP x i Indented paragraph with optional hanging tag. If the tag x is omitted, the entire following paragraph is indented by i. If the tag x is provided, it is hung at the left margin before the following indented paragraph (this is just like .TP except the tag is included with the command instead of being on the following line). If the tag is too long, the text after the tag will be moved down to the next line (text will not be lost or garbled). For bulleted lists, use this macro with \(bu (bullet) or \(em (em dash) as the tag, and for numbered lists, use the number or letter followed by a period as the tag; this simplifies translation to other formats. .TP i Begin paragraph with hanging tag. The tag is given on the next line, but its results are like those of the .IP command. Hypertext link macros .UR url Insert a hypertext link to the URI (URL) url, with all text up to the following .UE macro as the link text. .UE [trailer] Terminate the link text of the preceding .UR macro, with the op- tional trailer (if present, usually a closing parenthesis and/or end-of-sentence punctuation) immediately following. For non- HTML output devices (e.g., man -Tutf8), the link text is fol- lowed by the URL in angle brackets; if there is no link text, the URL is printed as its own link text, surrounded by angle brackets. (Angle brackets may not be available on all output devices.) For the HTML output device, the link text is hyper- linked to the URL; if there is no link text, the URL is printed as its own link text. These macros have been supported since GNU Troff 1.20 (2009-01-05) and Heirloom Doctools Troff since 160217 (2016-02-17). Miscellaneous macros .DT Reset tabs to default tab values (every 0.5 inches); does not cause a break. .PD d Set inter-paragraph vertical distance to d (if omitted, d=0.4v); does not cause a break. .SS t Subheading t (like .SH, but used for a subsection inside a section). Predefined strings The man package has the following predefined strings: \*R Registration Symbol: (R) \*S Change to default font size \*(Tm Trademark Symbol: tm \*(lq Left angled double quote: " \*(rq Right angled double quote: " Safe subset Although technically man is a troff macro package, in reality a large number of other tools process man page files that don't implement all of troff's abilities. Thus, it's best to avoid some of troff's more exotic abilities where possible to permit these other tools to work correctly. Avoid using the various troff preprocessors (if you must, go ahead and use tbl(1), but try to use the IP and TP commands instead for two-column tables). Avoid using computations; most other tools can't process them. Use simple commands that are easy to translate to other formats. The following troff macros are believed to be safe (though in many cases they will be ignored by translators): \", ., ad, bp, br, ce, de, ds, el, ie, if, fi, ft, hy, ig, in, na, ne, nf, nh, ps, so, sp, ti, tr. You may also use many troff escape sequences (those sequences beginning with \). When you need to include the backslash character as normal text, use \e. Other sequences you may use, where x or xx are any char- acters and N is any digit, include: \', \`, \-, \., \", \%, \*x, \*(xx, \(xx, \$N, \nx, \n(xx, \fx, and \f(xx. Avoid using the escape se- quences for drawing graphics. Do not use the optional parameter for bp (break page). Use only posi- tive values for sp (vertical space). Don't define a macro (de) with the same name as a macro in this or the mdoc macro package with a dif- ferent meaning; it's likely that such redefinitions will be ignored. Every positive indent (in) should be paired with a matching negative indent (although you should be using the RS and RE macros instead). The condition test (if,ie) should only have 't' or 'n' as the condi- tion. Only translations (tr) that can be ignored should be used. Font changes (ft and the \f escape sequence) should only have the values 1, 2, 3, 4, R, I, B, P, or CW (the ft command may also have no parame- ters). If you use capabilities beyond these, check the results carefully on several tools. Once you've confirmed that the additional capability is safe, let the maintainer of this document know about the safe command or sequence that should be added to this list. FILES /usr/share/groff/[*/]tmac/an.tmac /usr/man/whatis NOTES By all means include full URLs (or URIs) in the text itself; some tools such as man2html(1) can automatically turn them into hypertext links. You can also use the UR and UE macros to identify links to related in- formation. If you include URLs, use the full URL (e.g., <http://www.kernel.org>) to ensure that tools can automatically find the URLs. Tools processing these files should open the file and examine the first nonwhitespace character. A period (.) or single quote (') at the be- ginning of a line indicates a troff-based file (such as man or mdoc). A left angle bracket (<) indicates an SGML/XML-based file (such as HTML or Docbook). Anything else suggests simple ASCII text (e.g., a "cat- man" result). Many man pages begin with '\" followed by a space and a list of charac- ters, indicating how the page is to be preprocessed. For portability's sake to non-troff translators we recommend that you avoid using any- thing other than tbl(1), and Linux can detect that automatically. How- ever, you might want to include this information so your man page can be handled by other (less capable) systems. Here are the definitions of the preprocessors invoked by these characters: e eqn(1) g grap(1) p pic(1) r refer(1) t tbl(1) v vgrind(1) BUGS Most of the macros describe formatting (e.g., font type and spacing) instead of marking semantic content (e.g., this text is a reference to another page), compared to formats like mdoc and DocBook (even HTML has more semantic markings). This situation makes it harder to vary the man format for different media, to make the formatting consistent for a given media, and to automatically insert cross-references. By sticking to the safe subset described above, it should be easier to automate transitioning to a different reference page format in the future. The Sun macro TX is not implemented. SEE ALSO apropos(1), groff(1), lexgrog(1), man(1), man2html(1), groff_mdoc(7), whatis(1), groff_man(7), groff_www(7), man-pages(7), mdoc(7) COLOPHON This page is part of release 5.10 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/. Linux 2020-11-01 MAN(7)
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