Unset a readonly variable in bash. ITS JUST A PROOF OF CONCEPT! DONT USE THIS FOR REAL, ITS NASTY!!!

bash_unset_readonly_variable_poc.sh

#!/bin/bash
# Dennis Ullrich
# [email protected]
# 2017-06-17
# Unset readonly variable in bash
# ITS JUST A PROOF OF CONCEPT! DONT USE THIS FOR REAL, ITS NASTY!!!

readonly testvar="Bla bla"

unset testvar
#./test.sh: line 5: unset: testvar: cannot unset: readonly variable
echo "Content of testvar: \"$testvar\""

# Call the bash internal function via GNU Debugger
# Source definition at line 3168 of file variables.c.:
# int unbind_variable   (       char *  name    )       const
# {
#   SHELL_VAR *v, *nv;
#   int r;
#
#   v = var_lookup (name, shell_variables);
#   nv = (v && nameref_p (v)) ? find_variable_nameref (v) : (SHELL_VAR *)NULL;
#
#   r = nv ? makunbound (nv->name, shell_variables) : makunbound (name, shell_variables);
#   return r;
# }

# Let's use the knowledge (root user only or add sudo)
_unset(){
        type gdb >/dev/null || return false
        cat << EOH| gdb >/dev/null
                attach $$
                call unbind_variable("${1}")
                detach
EOH
# End of Hack ;)
}

_unset testvar

echo "Content of testvar: \"$testvar\""