Readonly

The unix readonly command is used for writing a unix Shell script that uses variables. This command allows the programmer to set a variable stored in The Shell (computing)'s variable list. This command sets a specified shell variable to not be changeable. After this is done it is not possible to alter that variable. This is done for storing the UUID of the logged in user of a shell, and can be used for making sure the variable never gets changed by another command.

Example

An example of a shell script that would use this would be

username="johnsmith"
readonly username
# ... call insecure function
    username="root" # this doesn't work
# continue regular code

Example

In most shells such as Bash (Unix shell), the readonly command is built-in and not in the users path. This can be determined by running the following command in your unix shell:

whereis readonly