.\"	$Id$
.\"
.\" Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
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.Dd $Mdocdate$
.Dt APROPOS 1
.Os
.Sh NAME
.Nm apropos
.Nd search manual page databases
.Sh SYNOPSIS
.Nm
.Op Fl C Ar file
.Op Fl M Ar path
.Op Fl m Ar path
.Op Fl S Ar arch
.Op Fl s Ar section
.Ar expression ...
.Sh DESCRIPTION
The
.Nm
utility queries manual page databases generated by
.Xr mandocdb 8 ,
evaluating on
.Ar expression
for each file in each database.
.Pp
By default,
.Nm
searches for
.Xr mandocdb 8
databases in the default paths stipulated by
.Xr man 1 ,
parses terms as case-sensitive regular expressions
.Pq the Li \&~ operator
over manual names and descriptions
.Pq the Li \&Nm No and Li \&Nd No macro keys .
Multiple terms imply pairwise
.Fl o .
.Pp
Its arguments are as follows:
.Bl -tag -width Ds
.It Fl C Ar file
Specify an alternative configuration
.Ar file
in
.Xr man.conf 5
format.
.It Fl M Ar path
Use the colon-separated path instead of the default list of paths
searched for
.Xr mandocdb 8
databases.
Invalid paths, or paths without manual databases, are ignored.
.It Fl m Ar path
Prepend the colon-separated paths to the list of paths searched
for
.Xr mandocdb 8
databases.
Invalid paths, or paths without manual databases, are ignored.
.It Fl S Ar arch
Search only for a particular architecture.
.It Fl s Ar cat
Search only for a manual section.
See
.Xr man 1
for a listing of manual sections.
.El
.Pp
An
.Ar expression
consists of search terms joined by logical operators
.Fl a
.Pq and
and
.Fl o
.Pq or .
The
.Fl a
operator has precedence over
.Fl o
and both are evaluated left-to-right.
.Bl -tag -width Ds
.It \&( Ar expr No \&)
True if the subexpression
.Ar expr
is true.
.It Ar expr1 Fl a Ar expr2
True if both
.Ar expr1
and
.Ar expr2
are true (logical
.Qq and ) .
.It Ar expr1 Oo Fl o Oc Ar expr2
True if
.Ar expr1
and/or
.Ar expr2
evaluate to true (logical
.Qq or ) .
.It Ar term
True if
.Ar term
is satisfied.
This has syntax
.Li [key[,key]*(=~)]?val ,
where operand
.Cm key
is an
.Xr mdoc 7
macro to query and
.Cm val
is its value.
See
.Sx Macro Keys
for a list of available keys.
Operator
.Li \&=
evaluates a substring, while
.Li \&~
evaluates a regular expression.
.It Fl i Ar term
If
.Ar term
is a regular expression, it
is evaluated case-insensitively.
Has no effect on substring terms.
.El
.Pp
Results are sorted by manual title, with output formatted as
.Pp
.D1 title(sec) \- description
.Pp
Where
.Qq title
is the manual's title (note multiple manual names may exist for one
title),
.Qq sec
is the manual section, and
.Qq description
is the manual's short description.
If an architecture is specified for the manual, it is displayed as
.Pp
.D1 title(cat/arch) \- description
.Pp
Resulting manuals may be accessed as
.Pp
.Dl $ man \-s sec title
.Pp
If an architecture is specified in the output, use
.Pp
.Dl $ man \-s sec \-S arch title
.Ss Macro Keys
Queries evaluate over a subset of
.Xr mdoc 7
macros indexed by
.Xr mandocdb 8 .
In addition to the macro keys listed below, the special key
.Cm any
may be used to match any available macro key.
.Pp
Names and description:
.Bl -column "xLix" description -offset indent -compact
.It Li \&Nm Ta manual name
.It Li \&Nd Ta one-line manual description
.El
.Pp
Sections and cross references:
.Bl -column "xLix" description -offset indent -compact
.It Li \&Sh Ta section header (excluding standard sections)
.It Li \&Ss Ta subsection header
.It Li \&Xr Ta cross reference to another manual page
.It Li \&Rs Ta bibliographic reference
.El
.Pp
Semantic markup for command line utilities:
.Bl -column "xLix" description -offset indent -compact
.It Li \&Fl Ta command line options (flags)
.It Li \&Cm Ta command modifier
.It Li \&Ar Ta command argument
.It Li \&Ic Ta internal or interactive command
.It Li \&Ev Ta environmental variable
.It Li \&Pa Ta file system path
.El
.Pp
Semantic markup for function libraries:
.Bl -column "xLix" description -offset indent -compact
.It Li \&Lb Ta function library name
.It Li \&In Ta include file
.It Li \&Ft Ta function return type
.It Li \&Fn Ta function name
.It Li \&Fa Ta function argument type and name
.It Li \&Vt Ta variable type
.It Li \&Va Ta variable name
.It Li \&Dv Ta defined variable or preprocessor constant
.It Li \&Er Ta error constant
.It Li \&Ev Ta environmental variable
.El
.Pp
Various semantic markup:
.Bl -column "xLix" description -offset indent -compact
.It Li \&An Ta author name
.It Li \&Lk Ta hyperlink
.It Li \&Mt Ta Do mailto Dc hyperlink
.It Li \&Cd Ta kernel configuration declaration
.It Li \&Ms Ta mathematical symbol
.It Li \&Tn Ta tradename
.El
.Pp
Physical markup:
.Bl -column "xLix" description -offset indent -compact
.It Li \&Em Ta italic font or underline
.It Li \&Sy Ta boldface font
.It Li \&Li Ta typewriter font
.El
.Pp
Text production:
.Bl -column "xLix" description -offset indent -compact
.It Li \&St Ta reference to a standards document
.It Li \&At Ta At No version reference
.It Li \&Bx Ta Bx No version reference
.It Li \&Bsx Ta Bsx No version reference
.It Li \&Nx Ta Nx No version reference
.It Li \&Fx Ta Fx No version reference
.It Li \&Ox Ta Ox No version reference
.It Li \&Dx Ta Dx No version reference
.El
.Sh ENVIRONMENT
.Bl -tag -width Ds
.It Ev MANPATH
Colon-separated paths modifying the default list of paths searched for
manual databases.
Invalid paths, or paths without manual databases, are ignored.
Overridden by
.Fl M .
If
.Ev MANPATH
begins with a
.Sq \&: ,
it is appended to the default list;
else if it ends with
.Sq \&: ,
it is prepended to the default list; else if it contains
.Sq \&:: ,
the default list is inserted between the colons.
If none of these conditions are met, it overrides the default list.
.El
.Sh FILES
.Bl -tag -width "/etc/man.conf" -compact
.It Pa whatis.db
name of the
.Xr mandocdb 8
keyword database
.It Pa whatis.index
name of the
.Xr mandocdb 8
filename database
.It Pa /etc/man.conf
default
.Xr man 1
configuration file
.El
.Sh EXIT STATUS
.Ex -std
.Sh EXAMPLES
Search for
.Qq mdoc
as a substring and regular expression
within each manual name and description:
.Pp
.Dl $ apropos mdoc
.Dl $ apropos ~^mdoc$
.Pp
Include matches for
.Qq roff
and
.Qq man
for the regular expression case:
.Pp
.Dl $ apropos ~^mdoc$ roff man
.Dl $ apropos ~^mdoc$ \-o roff \-o man
.Pp
Search for
.Qq optind
and
.Qq optarg
as variable names in the library category:
.Pp
.Dl $ apropos \-s 3 Va~^optind \-a Va~^optarg$
.Sh SEE ALSO
.Xr man 1 ,
.Xr re_format 7 ,
.Xr mandocdb 8
.Sh AUTHORS
The
.Nm
utility was written by
.An Kristaps Dzonsons Aq Mt kristaps@bsd.lv .