.Dd $Mdocdate: May 21 2023 $
.Dt HDOC 1
.Os Cytoplasm
.Sh NAME
.Nm hdoc
.Nd Generate documentation from a C header file.
.Sh SYNOPSIS
.Nm
.Op Fl i Ar file
.Op Fl o Ar file
.Op Fl D Ar key=value
.Sh DESCRIPTION
.Nm
is an extremely simple documentation generator that generates
a BSD man page from a specially-formatted C header file.
See
.Xr hdoc 5
for details on the format of this header file.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl i Ar file
The input C header file to read from. If this option is omitted,
then the standard input is read.
.It Fl o Ar file
The output BSD man page file to write. If this option is omitted,
then the standard output is written.
.It Fl D Ar key=value
Set the register
.Ar key
to
.Ar value .
.Nm
registers are used in various places, and can be set in either
the header file, or on the command line. Setting registers that
should be the same in all headers is best done from the command
line for maintainability purposes, but header-specific values
should be set in the header file itself.
.Pp
Registers are explained in more detail in
.Xr hdoc 5 .
.El
.Sh RETURN VALUE
.Pp
.Nm
returns a success value if the header is well-formed and the
man page is successfully generated. It returns an error code in
all other scenarios.
.Sh SEE ALSO
.Xr hdoc 5 ,
.Xr HeaderParser 3