.TH PROOF 1
.SH NAME
proof \- troff output interpreter
.SH SYNOPSIS
.B proof
[
.BI -m mag
]
[
.BI -/ nview
]
[
.B -F
.I dir
]
[
.B -d
]
[
.I file
]
.SH DESCRIPTION
.I Proof
reads
.IR troff (1)
intermediate language from
.I file
or standard input
and simulates the resulting pages on the screen.
.PP
After a page of text is displayed,
.I proof
pauses for a command from the keyboard.
The typed commands are:
.TP \w'newline\ \ \ 'u
newline
Go on to next page of text.
.TP
.B -
Go back to the previous page.
.TP
.B q
Quit.
.TP
.BI p n
Print page
.IR n .
An out-of-bounds page number means the end nearer to that number;
a missing number means the current page;
a signed number means an offset to the current page.
.TP
.I n
Same as
.BI p n\f1.
.TP
.B c
Clear the screen, then wait for another command.
.TP
.BI m mag
Change the magnification at which the output is printed.
Normally it is printed with magnification .9;
.IR mag "=.5"
shrinks it to half size;
.IR mag "=2"
doubles the size.
.TP
.BI x val
Move everything
.I val
screen pixels to the right (left, if
.I val
is negative).
.TP
.BI y val
Move everything
.I val
screen pixels down (up, if
.I val
is negative).
.TP
.BI / nview
Split the window into
.I nview
pieces.  The current page goes into the rightmost, bottommost piece,
and previous pages are shown in the other pieces.
.TP
.BI "-F " dir
Use
.I dir
for fonts instead of
.BR /lib/font/bit .
.TP
.B d
Toggle the debug flag.
.PD
.PP
These commands are also available, under slightly different form,
from a menu on button 3.  The
.B pan
menu item allows arbitrary positioning of the page:
after selecting
.BR pan ,
press the mouse button again and hold it down while moving
the page to the desired location.  The page will be redisplayed
in its entirety when the button is released.
Mouse button 1 also pans, without the need for selecting from a menu.
.PP
The
.BR m ,
.BR x ,
.BR y ,
.BR F ,
.BR / ,
and
.B d
commands are also available as command line options.
.SH FILES
.TF /lib/font/bit/MAP
.TP
.B /lib/font/bit/*
fonts
.TP
.B /lib/font/bit/MAP
how to convert troff output fonts and character names
into screen fonts and character numbers
.SH SOURCE
.B /sys/src/cmd/proof
.SH SEE ALSO
.IR lp (1), 
.IR gs (1),
.IR page (1)
.br
J. F. Ossanna and B. W. Kernighan,
``Troff User's Manual''