From Bash manual, a parameter is set if it has been assigned a value.
In bash, are the following two different concepts:
- a variable exists
- a variable has been assigned a value, i.e. is set?
unsetremoves a variable or function. Does
unsetmake a variable
- become non-existent, or
- still exists but become not assigned any value?
b=assign a value to variable
declarea variable creates a variable i.e. make a variable become exist?