echo出一些诡异变量

#!/bin/bash
# weirdvars.sh: Echoing weird variables.

echo

var="'(]\\{}\$\""
echo $var        # '(]\{}$"
echo "$var"      # '(]\{}$"     Doesn't make a difference.

echo

IFS='\'
echo $var        # '(] {}$"     \ converted to space. Why?
echo "$var"      # '(]\{}$"

IFS='$'
echo $var        # '(]\{} "     \ converted to $. Why?
echo "$var"      # '(]\{}$"
# Examples above supplied by Stephane Chazelas.

echo

var2="\\\\\""
echo $var2       #   "
echo "$var2"     # \\"
echo
# But ... var2="\\\\"" is illegal. Why?
var3='\\\\'
echo "$var3"     # \\\\
# Strong quoting works, though.

exit

NO.2

echo "Why can't I write 's between single quotes"

echo

# The roundabout method.
echo 'Why can'\''t I write '"'"'s between single quotes'
#    |-------|  |----------|   |-----------------------|
# Three single-quoted strings, with escaped and quoted single quotes between.

# This example courtesy of St閜hane Chazelas.

N0.3
bash$ echo hello\!
hello!


bash$ echo "hello\!"
hello\!


bash$ echo -e x\ty
xty


bash$ echo -e "x\ty"
x       y