#   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/>.
#
t() {
    printf '%s  |  %s\n' "$1" "$2"
  }
  v="'"       # v <- '

  #--
  t "${v/$'\''/$'\''}"        "'"
  t  ${v/$'\''/$'\''}         "'"
  t "${v/$'\''/x}"            "x"
  t  ${v/$'\''/x}             "x"
  t "${v/x/$'\''}"            "'"
  t  ${v/x/$'\''}             "'"
  t "${v/x/$'\x5c\''}"        "'" 
  t  ${v/x/$'\x5c\''}         "'" 
  t "${v/\'/\'}"              "'"
  t  ${v/\'/\'}               "'"
  t  ${v/\'/x}               "x"

echo "'"
echo "$'\''"

echo $'\''

echo $'\'abcd\''
echo "$'\'abcd\''"

v=1
echo ${v/1/\'}
echo ${v/\'/2}