apropos - search the manual page names and descriptions
(1) Does apropos always come up with nothing, or show you so many TCL functions you can't find the Unix commands? You can use the /usr/sbin/makewhatis script to create or modify the database that apropos reads. See MakeWhatIs.
(\b is the grep symbol for "word boundary". The single quotes prevent the shell from misinterpreting any grep symbols as commands to it.)
Each manual page has a short description available within it. apropos searches the descriptions for instances of keyword.
keyword is usually a regular expression, as if (-r) was used, or may contain wildcards (-w) , or match the exact keyword (-e) . Using these options, it may be necessary to quote the keyword or escape () the special characters to stop the shell from interpreting them.
Print debugging information.
Interpret each keyword as a regular expression. This is the default behaviour. Each keyword will be matched against the page names and the descriptions independently. It can match any part of either. The match is not limited to word boundaries.
Interpret each keyword as a pattern containing shell style wildcards. Each keyword will be matched against the page names and the descriptions independently. A match will only be found if an expanded keyword matches an entire description or page name.
Each keyword will be exactly matched against the page names and the descriptions.
If this system has access to other operating system's manual page descriptions, they can be searched using this option. To search NewOS's manual page descriptions, 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 whatis descriptions, include the system name man in the argument string. This option will override the $SYSTEM environment variable.
-M path, --manpath=path
Specify an alternate set of colon-delimited manual page hierarchies to search. By default, apropos uses the $MANPATH environment variable, unless it is empty or unset, in which case it will determine an appropriate manpath based on your $PATH environment variable. This option overrides the contents of $MANPATH.
Print a help message and exit.
Successful program execution.
Usage, syntax or configuration file error.
If $SYSTEM is set, it will have the same effect as if it had been specified as the argument to the -m option.
If $MANPATH is set, its value is interpreted as the colon-delimited manual page hierarchy search path to use.
A traditional global index database cache.
An alternate or FHS compliant global index database cache.