CODEWITHSUNDEEP
bashglobal-variables
Stepan Loginov
Stepan Loginov

Reputation: 1767

same variable in different scripts in bash

What better way to use same variable in two different bash scripts?

Simple example:

./set.sh 333
./get.sh
> 333
./set.sh 111
./get.sh
> 111

And how initialize that variable first time?

UPD:

$ cat get.sh
echo "$var"
$ cat set.sh
export var="$1"
$ chmod +x set.sh get.sh 
$ source set.sh
$ ./set.sh u
$./get.sh

$ source ./set.sh 2
$ ./get.sh
2

Upvotes: 1

Views: 322

Answers (3)

Beano
Beano

Reputation: 7851

What you need to understand is the lifetime of a shell variable (or an environment variable as you are using).

When you run a sub-shell, you are running a child process of the shell, and any shell variables that you set exist for the lifetime of the script. Any environment variables (shell variables are "promoted" to environment variable by the use of export) are copied into the environment of the child process - so changes to environment variables in a child process have NO effect on the value in the parent process.

So what you need to use is source which executes the contents of the script in the current shell (no sub-shell is spawned). Always source set.sh and you should be OK

Upvotes: 1

anubhava
anubhava

Reputation: 785581

You can have your scripts as:

cat set.sh 
export var="$1"

cat get.sh 
echo "$var"

chmod +x set.sh get.sh

Then call them:

. ./set.sh 333
./get.sh 
333

Please note that . ./set.sh OR source ./set.sh is called sourcing in the script which makes sure that set.sh is executed without creating a sub-shell and variables set in that script are accessible in the other scripts.

Upvotes: 1

michas
michas

Reputation: 26555

You have to store that number in a file.

A called shell script is not able to change the variables of the calling shell.

Another way is to source the shell script instead of running it as a separate process.

But maybe you should explain why you think, that you need that feature. Maybe some totally different solution is even better.

Upvotes: 0

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