Self-replicating program
This shell quine prints an exact copy of itself. This means that cat quine.sh and ./quine.sh are equivalent:
#!/bin/sh
# https://github.com/tingstad/quine
b='\'
s=\'
top='#!/bin/sh
# https://github.com/tingstad/quine
'
src='
echo "$top
b=$s$b$s
s=$b$s
top=$s$top$s
src=$s$src$s
$src"
'
echo "$top
b=$s$b$s
s=$b$s
top=$s$top$s
src=$s$src$s
$src"
It's therefore also equivalent to running sh <(sh <(./quine.sh)) or ./quine.sh > 1 ; sh 1 > 2 ; sh 2.
I did not want to use printf %s for this quine. The trick was to get the quoting right on the "recursion line", #14 (which has to match #9), I found the solution here.
In quine2.sh I wanted to avoid variable assignments and minimize string interpretation (no % and $) and just use simple printf and subroutines (parameter less functions).