espdiff.sh

A contemporary take on diff, the terminal control sequence and shell scripting in color

operate in situ on limited resource systems or within restrictive environments

need to know when it's time to wrap it up and archive an interim version?

something amiss? quickly see which file contains spurious punctuation

simply want to check whether your terminal supports 24bit direct-color?

• project-based and standalone modality

• visually assess progress on small projects or changes in files and directories

• persistently remembers the most recent project registration

• each project register may specify a custom palette

• 256color and 24bit direct-color support

• ECMA-48 conformance

• side-by-side human oriented output

• script includes help, a man page and footnote

• tested with xterm, lxterminal, rxvt, screen, tmux

getting started

extract example tarball:

tar -xf sample.tar

test basic function:

bash espdiff.sh example/previous/version-2/fileA example/previous/version-1/fileA

( type 'q' to exit less...)

make script executable:

chmod u+x espdiff.sh

./espdiff.sh

to include color name index:

cp .espdiffrc ~/

if terminal supports 24-bit direct-color:

echo "testdirect='true'" >> .esprj

view the register:

./espdiff.sh make

color swatch and ramp:

./espdiff.sh colors

  footnote

  xterm
    TERM='xterm-256color'
    menus C-left/right mouse

  tmux
    TERM='screen-256color' or 'tmux-256color'
    scrollback C-b [

  screen
    24bit direct-color in master branch (at least since 4.99)
    TERM='screen-256color'
    bce is not enabled by default
    C-a : bce on, or insert 'bce on' line into screenrc file

  less
    fast - files do not have to load completely before display begins
    caveat: no color buffer for hidden lines
    (scroll-back coloring is reversed)

  256color index
    lookup tables shipped onboard a vga graphics card eprom
    rgb levels were originally preconfigured to suit crt display hardware
    variation today can result from algorithm discrepancy or preference
   0-7 first 8 - ANSI color names, linux kernel system palette
    color selection was limited to this range initially
   8-15 next 8 - bright versions of first 8 colors, or may be bold font
    terminal themes are implemented in the first sixteen colors
   16-231 color cube - six intensity levels for  r, g, b  coordinates
    decimal  0, 95, 135, 175, 215, 255  (00, 5f, 87, af, d7, ff hex)
   232-255 greyscale - 24 shades,  8+(10*shade)
    8, 8, 8  -  238, 238, 238

  busybox
    if busybox is the default system shell:
     change shebang to !/bin/sh
     install full version of diff, builtin does not have '-y' option
    distribution binary does not pass unit test B:
     compile busybox-1.32.1 (latest stable)
      make defconfig
      make

  unit test - first line describes correct result

    B) displays 'qwe'
    a='asdfqwerty'; echo ${a:4:-3}
      error:
      sh: Illegal number: -3
    ${ substring expansion variable : offset parameter : -length is negative }
      in Bash since 4.2-alpha, busybox?

screenshot font is IBM Plex Mono Text