var sys = require('sys');
var exec = require('child_process').exec;
var cmd = 'whoami';
var child = exec( cmd,
function (error, stdout, stderr)
{
var username=stdout.replace('\r\n','');
}
);
var username = ?
How can I find username outside from exec function ?
You can pass the exec function a callback. When the exec function determines the username, you invoke the callback with the username.
var child = exec(cmd, function(error, stdout, stderr, callback) {
var username = stdout.replace('\r\n','');
callback( username );
});
Due to the asynchronous nature of JavaScript, you can't do something like this:
var username;
var child = exec(cmd, function(error, stdout, stderr, callback) {
username = stdout.replace('\r\n','');
});
child();
console.log( username );
This is because the line console.log( username ); won't wait until the function above finished.
Explanation of callbacks:
var getUserName = function( callback ) {
// get the username somehow
var username = "Foo";
callback( username );
};
var saveUserInDatabase = function( username ) {
console.log("User: " + username + " is saved successfully.")
};
getUserName( saveUserInDatabase ); // User: Foo is saved successfully.
You can write the "exec" statement in a function that has a callback... Like This
var sys = require('sys');
var exec = require('child_process').exec;
var cmd = 'whoami';
function execChild(callback){
var child = exec( cmd,
function (error, stdout, stderr)
{
username=stdout.replace('\r\n','');
callback(username);
}
)};
execChild(function(username){
console.log(username);
});
