#   This program is free software: you can redistribute it and/or modify
#   it under the terms of the GNU General Public License as published by
#   the Free Software Foundation, either version 3 of the License, or
#   (at your option) any later version.
#
#   This program is distributed in the hope that it will be useful,
#   but WITHOUT ANY WARRANTY; without even the implied warranty of
#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#   GNU General Public License for more details.
#
#   You should have received a copy of the GNU General Public License
#   along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
# expansions involving patterns
var='[hello'
echo "${var//[/}"

red='\[\e[0;31m\]'
printf "%s\n" "${red//\\[\\e/}"

foo="${red//\\[\\e/}"

# foo == [0;31m\]
printf "%s\n" "${foo//[0;31m\\/}"

echo "${var//[]/}"
echo "${red//[]/}"

v=hello
foo='[:alpha:]'

echo ${v//[[:alpha:]]/}
echo ${v//[[:alpha]]/}
echo ${v//[[:alpha]/}