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In ksh, I have two variables with the same name , one global , other one is local to a function

#!/bin/ksh

LOG_FILE=lf

function exec_script
{
   local LOG_FILE=f
   print $LOG_FILE
}
exec_script
print $LOG_FILE

If I want to refer the global variable $LOG_FILE within exec_script function, how should I qualify it so that the local does not get referenced ?

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  • I bet you can't, but I don't know. Good question though. Commented Sep 30, 2013 at 15:20
  • Is acceptable for you to save global variable before the redefinition, like G_LOG_FILE=$LOG_FILE? Commented Sep 30, 2013 at 15:23
  • @dchirikov , Thank you. Currently I am using two seperate variables, prepending the local var name with a L.but I don't like it :). I am looking for something equivalent to a namespace or that sort as we have in C++. Commented Sep 30, 2013 at 15:44
  • 1
    I prepend all of my local variables with loc_ so they are readily identified in scripts. This would always prevent conflicts between local and global. (I also prepend my read-only variables with const_ for the same readability reasons. If it's both I use cloc_ for those.) Also, never use all-caps variable names in your shell scripts or you risk overwriting an unanticipated system variable. Commented Oct 9, 2024 at 21:10

1 Answer 1

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I don't think that you can. I think it's a limitation of how Ksh interrogates the environment when looking for a variable's scoping.

excerpt from Scope of variables in KSH

Ksh has dynamic scoping, so the variable is also accessible in functions that are invoked by the function that declares the variable. This is tersely documented in the section on functions in the manual. Note that in AT&T ksh (as opposed to pdksh and derivatives, and the similar features of bash and zsh),

excerpt Parameters: An Overview

When you read or set a variable, zsh looks in the current function to see if that variable exists. If not, it looks in the next outermost function, and so on, until it reaches the global (outermost) scope. Therefore, if you assign a value to a variable that doesn't exist, the variable gets created in the outermost scope. (Exporting a new parameter also has this effect.)

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  • Allow me to be dumb to ask this question, whatever ksh has , is it derived or adapted from zsh? Commented Oct 1, 2013 at 12:13
  • @user917279 - sorry for the confusion. I originally mis-read your question thinking it was asking about just Zsh. Here's additional details regarding Ksh as well. Commented Oct 1, 2013 at 13:17
  • thank you. I went through that link before, stumbled on namespaces and compound variables, trying to figure out how could it solve my problem. Commented Oct 1, 2013 at 14:21
  • @user917279 - I think you're going to have to add logic to save your global variables to alternative names while in functions or use different names for the local variables. Not finding much in the way of methods to deal with this. Commented Oct 1, 2013 at 15:11
  • Please remove the references to zsh. It is confusing given the OP. Commented Feb 21, 2018 at 21:31

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