Bash function variables persist between calls

Question

#!/bin/sh/

function test() {
       echo BEFORE var1 $var1
       echo BEFORE var1 $var1

       var1=$1
       var2=$2

       echo AFTER var1 $var1
       echo AFTER var1 $var1
}

test 1 2
test 3 4

Result:

BEFORE var1
BEFORE var2
AFTER var1 1
AFTER var2 2
BEFORE var1 1
BEFORE var2 2
AFTER var1 3
AFTER var2 4

Why does var1 and var2 keep the values from the first time the function is called when the second time the function is called? How do I get the variables to clear every time?

The code you posted and the output cannot have been generated by the same script. Please update your post, so that both match. — RedX
– RedX, Commented Dec 8, 2014 at 17:54

RedX · Accepted Answer · 2014-12-08 17:55:43Z

3

You are looking for the local keyword.

Try

function test() {
       local var1
       local var2
       echo BEFORE var1 $var1
       echo BEFORE var1 $var1

       var1=$1
       var2=$2

       echo AFTER var1 $var1
       echo AFTER var1 $var1
}

answered Dec 8, 2014 at 17:55

RedX

15.3k2 gold badges57 silver badges81 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

glenn jackman Over a year ago

@terence, note that local is a bash command, so change your shebang to #!/bin/bash

chepner Over a year ago

function is also a bash keyword.

chepner · Accepted Answer · 2014-12-08 21:27:04Z

0

Yet another approach:

test () (
    echo "BEFORE var1 $var1"
    echo "BEFORE var2 $var2"

    var1="$1"
    var2="$2"

    echo "AFTER var1 $var1"
    echo "AFTER var2 $var2"
)

Values of var1 and var2 that exist outside the function will be seen for the "BEFORE" lines, but the changes shown in the "AFTER" lines will be local to the function. This is an all-or-none approach; you cannot change global variables inside the subshell created by the function, but this doesn't require any non-POSIX features.

answered Dec 8, 2014 at 21:27

chepner

538k77 gold badges595 silver badges747 bronze badges

Collectives™ on Stack Overflow

Bash function variables persist between calls

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related