Linux Knowledge Base and Tutorial

SYNOPSIS

man [-c|-w|-tZHT device] [-adhu7V] [-i|-I] [-m sys tem[,...]] [-L locale] [-p string] [-M path] [-P pager] [-r prompt] [-S list] [-e extension] [[section] page ...] ... man -l [-7] [-tZHT device] [-p string] [-P pager] [-r prompt] file ... man -k [apropos options] regexp ... man -f [whatis 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 func tion. The manual page associated with each of these argu ments is then found and displayed. A section, if provided, will direct man to look only in that section of the man ual. The default action is to search in all of the avail able sections, following a pre-defined order 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 eg /etc/passwd 6 Games 7 Miscellaneous (including macro packages and conven tions), e.g. man(7), groff(7) 8 System administration commands (usually only for root) 9 Kernel routines [Non standard] A manual page consists of several parts. They may be labelled NAME, SYNOPSIS, DESCRIPTION, OPTIONS, FILES, SEE ALSO, BUGS, and AUTHOR. 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. The command or function illustration is a pattern that should match all possible invocations. In some cases it Format the manual page referenced by `alias', usually a shell manual page, 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 indepen dent (dvi) file. The redirection 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 -r printf. man -f smail Lookup the manual pages referenced by smail and print out the short descriptions of any found. Equivalent to whatis -r 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, section order, output processor, and other behaviours and operations detailed 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 (preceded by a back slash). 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 options 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. The manual pager utilities packaged as man-db make exten sive use of index database caches. These caches contain information such as where each manual page can be found on the filesystem and what its whatis (short one line description of the man page) contains, and allow man to run faster than if it had to search the filesystem each time to find the appropriate manual page. If requested information must be known at compile time. Also, by default, any cat pages produced are compressed using gzip. Each `global' manual page hierarchy such as /usr/share/man or /usr/X11R6/man may have any directory as its cat page hierarchy. Traditionally the cat pages are stored under the same hierarchy as the man pages, but for reasons such as those specified in the File Hierarchy Standard (FHS), it may be better to store them elsewhere. For details on how to do this, please read manpath(5). For details on why to do this, read the standard. International support is available with this package. Native language manual pages are accessible (if available on your system) via use of locale functions. To activate such support, it is necessary to set either $LC_MESSAGES, $LANG or another system dependent environment variable to your language locale, usually specified in the POSIX 1003.1 based 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. Support for international message catalogues is also fea tured in this package and can be activated in the same way, again if available. If you find that the manual pages and message catalogues 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. For information regarding other features and extensions available with this manual pager, please read the docu ments supplied with the package.

DEFAULTS

man will search for the desired manual pages within the index database caches. If the -u option is given, a cache consistency check is performed to ensure the databases accurately reflect the filesystem. If this option is always given, it is not generally necessary to run mandb after the caches are initially created, unless a cache becomes corrupt. However, the cache consistency check can be slow on systems with many manual pages installed, so it is not performed by default, and system administrators may wish to run mandb every week or so to keep the database caches fresh. To forestall problems caused by outdated caches, man will fall back to file globbing if a cache lookup fails, just as it would if no cache was present. 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 initial line of the nroff file is parsed for a preprocessor string. To con tain 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 informa tion, a default set is used. A formatting pipeline is formed from the filters and the primary formatter (nroff or [tg]roff with -t) and exe cuted. 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 speci fied 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 argument, each duplication will override the previous argument value. -l, --local-file Activate `local' mode. Format and display local manual files instead of searching through the sys tem'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 required, 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. -L locale, --locale=locale man will normally determine your current locale by a call to the C function setlocale(3) which inter rogates various environment variables, possibly including $LC_MESSAGES and $LANG. To temporarily override the determined value, use this option to supply a locale string directly to man. Note that it will not take effect until the search for pages actually begins. Output such as the help message 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. -P pager, --pager=pager Specify which output pager to use. By default, man uses exec /usr/bin/less -s. This option overrides the $PAGER environment variable and is not used in conjunction with -f or -k. -r prompt, --prompt=prompt If a recent version of less is used as the pager, man will attempt to set its prompt and some sensi ble 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 surrounded 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\\%.. It is broken into two 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 pre ceding 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. If you want to override man's prompt string pro cessing completely, use the $MANLESS environment variable described below. -7, --ascii When viewing a pure ascii(7) manual page on a 7 bit If the latin1 column displays correctly, your ter minal 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 using 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. -S list, --sections=list List is a colon-separated list of `order specific' manual sections to search. This option overrides the $MANSECT environment variable. -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. -c, --catman This option is not for general use and should only be used by the catman program. -d, --debug Don't actually display any manual pages, but do print lots of debugging information. -e sub-extension, --extension=sub-extension Some systems incorporate large packages of manual pages, such as those that accompany the Tcl pack age, 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 situa tion and to avoid having to know which section the page you require resides in, it is now possible to give man a string indicating which package the page must belong to. Using the above example, supplying the option -e tcl to man will restrict the search to pages having an extension of *tcl. -k, --apropos Equivalent to apropos. Search the short manual page descriptions for keywords and display any matches. See apropos(1) for details. -m system[,...], --systems=system[,...] If this system has access to other operating sys tem's 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 operating system names. To include a search of the native operating system's manual pages, include the system name man in the argument string. This option will override the $SYSTEM environment variable. -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 preprocessors. Some of the pre processors and the letters used to designate them are: eqn (e), grap (g), pic (p), tbl (t), vgrind (v), refer (r). This option overrides the $MAN ROFFSEQ environment variable. zsoelim is always run as the very first preprocessor. -u, --update This option causes man to perform an `inode level' consistency check on its database caches to ensure that they are an accurate representation of the filesystem. It will only have a useful effect if man is installed with the setuid bit set. -t, --troff Use /usr/bin/groff -mandoc to format the manual page to stdout. This option 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 (pro vided with Groff-1.17) include dvi, latin1, ps, utf8, X75 and X100. -Z, --ditroff groff will run troff and then use an appropriate post-processor to produce output suitable for the chosen device. If /usr/bin/groff -mandoc is groff, designed, the argument to this function must be an nroff device such as ascii, latin1, or utf8. -w, --where, --location Don't actually display the manual pages, but do print the location(s) of the source nroff files that would be formatted. -W, --where-cat, --location-cat Don't actually display the manual pages, but do print the location(s) of the cat files that would be displayed. If -w and -W are both specified, print both separated by a space. -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. MANROFFSEQ If $MANROFFSEQ is set, its value is used to deter mine 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 sections and it is used to determine which manual sections to search and in what order. PAGER If $PAGER is set, its value is used as the name of the program used to display the manual page. By default, exec /usr/bin/less -s is used. MANLESS If $MANLESS is set, man will not perform any of its usual processing to set up a prompt string for the SYSTEM If $SYSTEM is set, it will have the same effect as option -m string where string will be taken as $SYSTEM's contents. 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 environ ment 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 inter preted as part of an option's argument 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, manual pages will be formatted with a line length appropriate to the current ter minal (using an ioctl(2) if available, the value of $COLUMNS, or falling back to 80 characters if nei ther is available). Cat pages will only be saved when the default formatting can be used, that is when the terminal line length is between 66 and 80 characters. 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 available). See setlocale(3) for precise details.

FILES

/etc/manpath.config man-db configuration file. /usr/share/man A global manual page hierarchy. /usr/share/man/index.(bt|db|dir|pag) A traditional global index database cache. /var/cache/man/index.(bt|db|dir|pag) An alternate or FHS compliant global index database cache.

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