Use of read-only variables in shell scripts [closed]

Question

Is it good shell programming practice to use read-only variables whenever possible or does it have any drawbacks? E.g. if I wanted to write some script that consists of multiple script files that make use of immutable file paths, would it make sense to declare the paths like that:

readonly LOGS
export LOGS 
LOGS="/some/path"

Another question: Is it a good idea to split monolithic and tedious too read shell script code into separate files? Many thanks for your answers.

Answer 1

It sounds like you might think that readonly does more than it really does. For one thing, readonly status is not exported into the environment or inherited by child processes:

$ declare -rx LOGS=hello
$ LOGS=goodbye
bash: LOGS: readonly variable
$ bash -c 'echo "$LOGS"'
hello
$ bash -c 'LOGS=goodbye; echo "$LOGS"'
goodbye
$ 

Answer 2

A classic use of read-only variables is with TMOUT. Setting this variable to a non-zero value will logout an interactive terminal session after TMOUT seconds of inactivity (i.e. no keyboard input). To defeat a smart user from overriding the setting, use readonly:

readonly TMOUT=60

Having done this, there is no way to do:

export TMOUT=0