.TH GPP 1 GPP
.SH NAME
gpp - Bash-based preprocessor for anything
.PP
gpp: General Preprocessor
.SH SYNOPSIS
.BR gpp
.RI [ OPTION ]...
.SH DESCRIPTION
.B gpp
lets a developer embed directives written in
.B GNU Bash
into any text document. These directives are used
to automate the writting of parts of the document.
.PP
The preprocessing directives start with a symbol (or
text string) specified by the developer. By default
this symbol is \fB@\fP (at).
.PP
Any line starting with \fB@<\fP (where \fB@\fP is
the selected symbol for preprocessing directives)
or \fB@>\fP, or is between a line starting with
\fB@<\fP and a line starting with \fB@>\fP, is parsed
as a line, written in
.BR bash (1),
that is executed during preprocessing. A \fB@<\fP
line must have an associated \fB@>\fP line somewhere
after it, all lines between them are parsed as
preprocessing directives. A \fB@>\fP does however
not need an associated \fB@<\fP line somewhere before
it, making \fB@>\fP suitable for single line directives.
.PP
Preprocessing directives can also be inline. For this,
use
.BI @( COMMAND )
where
.I COMMAND
is the
.BR bash (1)
code to run. Additionally,
.B gpp
supports variable substitution.
.BI @{ VARIABLE }
will be replaces by the value if the variable
(possibility environment variable)
.IR VARIABLE .
.B gpp
supports all modifiers that
.BR bash (1)
supports. For example, if you want the value to be
included but uppercase you can write
.BR @{ \fIVARIABLE\fP ^^} ,
or
.BI @{ VARIABLE ,,}
for lowercase.
.PP
Everything that is not preprocessing directives is
threaded as
.BR echo (1):ed
lines.
.SH OPTIONS
.TP
.BR \-s ,\ \-\-symbol \ \fISYMBOL\fP
Set the prefix symbol for preprocessor directives.
Defaults to @ (at).
.TP
.BR \-e ,\ \-\-encoding \ \fIENCODING\fP
Specifies the encoding of the file.
.TP
.BR \-n ,\ \-\-iterations \ \fIN\fP
Process the file recursively \fIN\fP times. Defaults to 1 time.
.TP
.BR \-u ,\ \-\-unshebang
Clear the shebang line, remove it if this flag
is used twice. If used twice, an empty line
will be inserted after the new first line.
.TP
.BR \-i ,\ \-\-input \ \fIFILE\fP
Select file to process. Defaults to /dev/stdin.
.TP
.BR \-o ,\ \-\-output \ \fIFILE\fP
Select output file. Defaults to /dev/stdout.
.TP
.BR \-f ,\ \-\-file \ \fIFILE\fP
Equivalent to \-i \fIFILE\fP \-o \fIFILE\fP.
.TP
.BR \-D ,\ \-\-export \ \fINAME\fP=\fIVALUE\fP
Set the environment variable \fINAME\fP to hold
the value \fIVALUE\fP.
.TP
.BR \-D ,\ \-\-export \ \fINAME\fP
Set the environment variable \fINAME\fP to hold
the value 1.
.TP
.BR \-v ,\ \-\-version
Print program name and version and exit.
.TP
.BR \-c ,\ \-\-copying
Print copyright notice and exit.
.PP
Short options must be joined. The value of a flag must
be in a separate argument from the flag itself.
.SH RATIONALE
Programmers need more automation when we write software
and documentation. An unrestricted preprocessor lets
you automate just about anything. Of course, it can be
used for anything, must just writing software and
documentation. Preprocessing can be used for more than
automation, it can also be used to increase the flexibility
of the work.
.PP
C is one of the few languages that includes a preprocessor,
some times it is not enough; and all languages need
preprocessors.
.SH "SEE ALSO"
.BR bash (1),
.BR jpp (1),
.BR cpp (1),
.BR env (1)
.PP
Full documentation available locally via: info \(aq(gpp)\(aq
.SH AUTHORS
Principal author, Mattias Andrée. See the COPYING file for the full
list of authors.
.SH LICENSE
Copyright \(co 2013, 2014, 2015, 2017 Mattias Andrée
.br
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>.
.br
This is free software: you are free to change and redistribute it.
.br
There is NO WARRANTY, to the extent permitted by law.
.SH BUGS
Please report bugs to https://github.com/maandree/passcheck/issues or to
maandree@member.fsf.org
