While refactoring a large Bash script you notice that a for-loop counter declared inside a helper function is overwriting a variable of the same name that was set earlier in the calling script. The counter should live only for the lifetime of the function call, must NOT be exported to child processes, and should vanish once the function returns. Which built-in command, placed directly in front of the variable assignment, meets these scoping requirements?
The built-in command that limits a variable's visibility to the current function (and any functions it calls) is "local". Declaring a variable with local creates a temporary shell variable that shadows any variable of the same name outside the function and is automatically discarded when the function finishes, so nothing leaks to the caller or the environment.
"export" adds the variable to the process environment, making it visible to the caller and every child process-exactly the opposite of the requirement.
"readonly" prevents further modification but does not change scope; the variable remains global in the shell and can still clobber the earlier value.
"declare -g" (or typeset -g) explicitly forces the variable to be global even when used inside a function, so the unwanted overwrite would persist. Therefore, only "local" achieves the requested behavior.
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What is the purpose of the 'local' command in Bash scripting?
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How does 'local' differ from 'export' in terms of scope?
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Can you use 'local' outside of a function in Bash? Why or why not?
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