CODEWITHSUNDEEP
shellmemoryfreelocal-variables
장동욱
장동욱

Reputation: 17

How to 'free' memory allocated to a variable in shell

function mem(){
local token
return $token
}

obj=$(ls)                      #list of object name
objstr=($obj)                  #array[i] whose ith element is object name
objno=$(echo "$obj" | wc -w)   #the number of object name

for i in $(seq 0 $(($objno-1)))
do
    objID=${objstr[$i]}    #object name
    IDlen=${#objID}        #length of object name
    for j in $(seq 0 $(($IDlen-1)))
    do
        subID=${objID:$j:1}        #charater in the name
        token=$(mem)               #allocate local variable returned
        token[0]+=$subID           #concatenate characters
    done

I want to define a variable in which I can store an objects name. (in a way that I can access each characters in the name) But the most important thing is that it has to be disposable. I want to 'free' the memory allocated to the variable before going on with another object name to minimize overhead. So I defined a function, mem() which would return local variable. If I initialize token[0] to the returned variable each time before I use it, what happens to the memory previously allocated to the variable? Is it 'free'ed as intended?

Upvotes: 0

Views: 2518

Answers (1)

Jens
Jens

Reputation: 72707

You don't free memory in the shell; there are no explicit ways to free such things as the storage for variables. That said, you could try

  • using local variables if your shell supports them; they may get freed when they go out of scope
  • unset NAME once you're done with NAME

Note that just like in C, this doesn't guarantee the memory is returned to the OS.

But then, why do you worry about memory for shell variables in the first place? What is your actual problem? If memory use and management is a constraint, maybe the shell is the wrong tool?

Upvotes: 2

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