6.2.3 GNU troff Output Examples

This section presents the output GNU troff generates from the same input formatted for three different devices. The input is the phrase ‘hell world’ piped to GNU troff on the command line.

High-resolution device ps

We depict the standard output stream of GNU troff in its default build configuration and in the absence of an explicit -T option.

shell> echo "hell world" | groff -Z -T ps

x T ps
x res 72000 1 1
x init

p1
x font 5 TR
f5
s10000
V12000
H72000
thell
wh2500
tw
H96620
torld
n12000 0

x trailer
V792000
x stop

This output can be placed onto the standard input stream of grops to produce its representation as a PostScript file.

Low-resolution device latin1

This is similar to the high-resolution device except that the positioning is done at a minor scale. Some comments (lines starting with ‘#’) were added for clarification; they were not generated by the formatter.

shell> echo "hell world" | groff -Z -T latin1

# header
x T latin1
x res 240 24 40
x init

# begin a new page
p1
# font setup
x font 1 R
f1
s10
# initial positioning on the page
V40
H0
# write text 'hell'
thell
# inform about space, and issue a horizontal jump
wh24
# write text 'world'
tworld
# announce line break, but do nothing because...
n40 0

# ...the end of the document has been reached
x trailer
V2640
x stop

This output can be placed onto the standard input stream of grotty to produce its representation as text file.

AT&T troff output

Since a video display has lower resolution than modern printers, GNU troff’s output for X11 devices can use the legacy compressed encoding.

shell> echo "hell world" | groff -Z -T X100

x T X100
x res 100 1 1
x init

p1
x font 5 TR
f5
s10
V16
H100
# write text in legacy compressed encoding
ch07e07l03lw06w11o07r05l03dh7
n16 0

x trailer
V1100
x stop

Place the foregoing into the standard input stream of xditview or gxditview to display it in an X11 window.

The legacy compressed encoding makes the content of formatted text in AT&T troff output almost incomprehenible.