$ mySite="superuser"
$ readonly mySite
$ unset mySite
bash: unset: mySite: cannot unset: readonly variable
How can we delete mySite, as it is a readonly variable?
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As said below, there is a thread on StackOverflow with answers, with and without GDB.– bufhDec 12, 2019 at 14:12
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3 Answers
You can't delete mySite. The whole point of the readonly command is to make it final and permanent (until the shell process terminates). If you need to change a variable, don't mark it readonly.
answered Oct 27, 2012 at 4:07
Walker Hale IV's solution can be expressed in a much shorter fashion using options available in more recent versions of gdb:
gdb --batch-silent --pid=$$ --eval-command='call unbind_variable("mySite")'
Again, this is dark magic that should be kept well away from production environments.
answered Apr 29, 2019 at 5:22
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Got error:
'unbind_variable' has unknown return type; cast the call to its declared return type. The declared return type isint(github.com). Success after adding(int):gdb --batch-silent --pid=$$ --eval-command='call (int) unbind_variable("mySite")'May 12, 2021 at 19:31
See https://stackoverflow.com/a/21294582/642372
This is dark magic. It uses gdb to tell the bash process to clear the variable by calling an internal C function.
mySite="superuser"
readonly mySite
gdb -n <<EOF >>/dev/null 2>&1
attach $$
call unbind_variable("mySite")
detach
quit
EOF
You should never have this in production. I have it in my .bashrc. 😉
