CODEWITHSUNDEEP
linuxbash
Michael Lafayette
Michael Lafayette

Reputation: 3072

Bash - Is it a good idea to make all variables local?

I'm writing a compiler that compiles into bash. It seems like a pain to declare some variables as local and some as global - I can declare variables as local even when I'm not inside a function. Is it a good idea to make all variables local in bash?

Upvotes: 1

Views: 1865

Answers (1)

user1529891
user1529891

Reputation:

You should use global variables only when needed because it makes it harder to debug; the bash official docs say this regarding local variables:

local [option] [name[=value] ...] .

For each argument, a local variable named name is created, and assigned value. The option can be any of the options accepted by declare. When local is used within a function, it causes the variable name to have a visible scope restricted to that function and its children. With no operands, local writes a list of local variables to the standard output. It is an error to use local when not within a function. The return status is 0 unless local is used outside a function, an invalid name is supplied, or name is a read‐ only variable.

You should local variables only when you're in a function otherwise it will error.

You should also take a look at what variable scope means. If you make all variables global scope, then its going to be painful to debug. If you make var a global scope, and then shadow it (accidentally maybe) within a function as var a, creating a local scope, you'll make it even harder to debug.

Upvotes: 3

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