Frozen Fish 1: Amiga/FrozenFish-Apr94.iso/bbs/alib/d5xx/d511/less.lha/Less/ReadMe

Text File | 1991-07-20 | 8KB | 153 lines

This is a revision of a port (by Bob Leivian) of version 73 of the "Less"
pager from Unix (Fred Fish #149).

Less is an Ascii text pager with the following features:

    -Compatible with WB 1.3 and 2.0 on any Amiga
    -Handles NTSC, PAL, overscan, etc. screens
    -Works with pipes (with a consenting shell or pipe: device)
    -Permits multiple file selection, CLI or Workbench
    -Forward & backward movement in a variety of ways
    -Powerful searches, using regular expression patterns
    -Handles alternative fonts
    -Handles international Ascii characters
    -Handles boldface, underline, etc. in ANSI or Unix nroff style
    -Customizable, using environment or command options
    -Residentable

Less is still the only pager I know of on the Amiga that handles pipes
and multiple file selection.  To me, these two features are essential
in a pager.  If your shell supports pipes and expands wildcards (I use
Steve Koren's outstanding SKsh), you can write things like 'ls | less'
or 'less *.readme'.

Less has been around for a long time in the Unix world, and has been
ported to the Amiga before.  Unfortunately, the earlier Amiga port would
not run on Amiga 3000s and was seriously crippled in the areas of support
for non-NTSC or overscan screens and international characters.

The current version opens a full-sized window on your workbench screen
(even PAL or overscan), and displays as much text from the input
files as it can using the standard system font.  It is smart enough to
adjust these values even if you resize the window using the resizing
gadget.  It responds to the standard window close gadget, and of course
front/back, drag bar, and 2.0 zoom gadgets.

You can specify less than a full-sized window from the command line by
a new option, -[N,N,N,N].  The four N's are left-edge position, top-edge
position, width, and height in pixels.  Any may be omitted, defaulting
to 0.  Zeros in the last two positions mean full width or height.  If
numbers at the end of the list are omitted, their preceding commas may
be omitted also.  If any of the Ns are negative, they are taken to be
relative to the bottom right corner of the screen.  Thus, [-200,-100,
200,100] would be a 200 by 100 window in the bottom right corner of the
screen, and [0,12,0,-100] would be a full-width window leaving the title
bar of the screen and the bottom 100 scan lines exposed.  There is a
minimum window size, and if it is violated, or if the window would fall
off the edges of the screen, Less simply forces things to conform.

It recognizes most ANSI commands to set underlining, italics, boldfacing,
or inverse video, in addition to the backspace protocols for boldfacing
and underlining that Less has always recognized (if neither of the two
-u options is set).

This version of Less is more "Amigatised" in its use of the Amiga keyboard.
It allows you to scroll backward in the file by one line using the
backspace key--a sort of logical consequence, IMHO, of the carriage
return key's use for scrolling forward by single lines.  The arrow keys
(cursor up, down, left and right) are active:  up and down move you
through the document by pages; left and right by lines; shifted left
and right by half-pages.  The HELP key displays a help message.  I
have added ^N and ^P for next and previous line, ^V for next page, ^S
for forward search, and '<' and '>' for go to top and bottom of file, in
response to a request from an emacs-type.

Workbench support is expanded to handle multiple selection of files to
be viewed.  You cannot enter -options from workbench like you can from
CLI, but Less *does* act upon whatever options are set in the environment
variable LESS.

Less version 1.4Z recognizes the international character set between
characters 160 and 255 (decimal).

The regular expression pattern matching in searches has been enabled.
These use the powerful Unix 'ed' style patterns.  Any pattern consisting
only of letters, numbers, and spaces will simply search for the given
pattern.  But you can use one or more of the metacharacters [].^$()|*+ to
engineer very sophisticated searches.  The '.' stands for any single
character, and 'x*' stands for 0 or more occurances of x (so 'x.*y'
would match anything that started with x and ended with y).  'x+'
works the same way, for 1 or more occurances of x.  'x?' matches 0 or 1
occurances of x (i.e. 'x' or nothing).  '[abc]' matches any single
occurance of 'a', 'b', or 'c'.  '[^abc]' matches any single character
except 'a', 'b', or 'c'.  '[a-m]' matches any single character in the
range 'a' through 'm' inclusive.  '^x' finds x only at the beginning of
a line; 'x$' only at the end of a line.  'x|y' matches either x or y.  The
various pieces can be combined, of course, and grouped with parentheses.
'([Aa]ny|[Ee]ach) +of you' would find any phrase beginning with 'any'
or 'each' (possibly capitalized) followed by one or more blanks, followed
by 'of you'. ' (can)?not ' matches either 'not' or 'cannot', but not
'nothing' or 'cancel'.  '[^a-zA-Z]i[^a-zA-Z]' finds all occurances of a
variable 'i' in a program, but does not find 'i' embedded in other
variable names or words.  To match a metacharacter literally, precede it
with a backslash; e.g. '\.  \*' would match a period followed by two
spaces and an asterisk.

With resizeable windows, the number of lines to scroll for page-forward
and page-back commands is now recalculated each time the screen is
resized.  The -z command now sets the maximum number of lines that will
be scrolled for full-screen movement.  The space bar, for instance, will
scroll either -z lines, or a full screen, whichever is less.

Half-page moves used to be fixed at 10 lines (although alterable
by prefixing a u or d command with a different number).  With resizable
screens, this didn't seem to make much sense any more, so I also have
Less automatically compute the half-page size on startup and resizing of
the window.

Many bugs or unimplemented features have been fixed; they're generally
small things that casual users will never notice.  The Q and q options
work:  they quiet the visible bell, since there is no audible bell.  The
E and e options have changed meaning slightly:  You can exit a file upon
any attempted forward movement beyond eof (E), or only upon an attempted
full-page movement (e, the default), or you can be barred from exiting
via text movement commands (neither e nor E).  The old business of closing
the window immediately (old E) upon finding eof, before you have time to
read the last page of text, was judged useless in the Amiga environment!
C was made the default for painting screens, for speed.  This version
takes greater pains to assure that the prompt at the bottom of the screen
fits in a single line; it is shortened if necessary.  Some bug fixes have
made it harder (I think!) to crash Less (no pun intended).

Signal handling has been improved:  ^C in the Less window will abort
searches, but is otherwise ignored with a warning message.  A BREAK
signal from the launching CLI (^C in the CLI window, if there is one,
or AmigaDOS "break" command directed at Less) will immediately
terminate the process (with cleanup, of course).  Error handling in
connection with reading the files is much improved, with emphasis on
more informative error messages.

I removed two "features" of the old Amiga port:  Less1.4Z no longer
internally expands wildcarded filenames, and it no longer prints files
on the system printer.  I think both of these functions are better done
by other means; e.g. SKsh or some other shell for wildcard expansion,
and copying to prt: or using one of the many printer utilities to get
printouts.  Less is a good pager; it doesn't need to be bogged down and
fattened up with random other capability.  In any event, since I didn't
need or want these functions, it seemed a lot easier to remove them
than to rewrite them.

The "clean data" option of the original Unix no longer makes sense in
this version, and has been deleted.

Less1.4Z was compiled with SAS-C (formerly Lattice) v5.10a, using the
version 2.0 include files.

--------------------------------------------------------------

Ray Zarling
California State Univ. Stanislaus
Turlock, CA 95380

[e-mail]