Getting 0KB of size file while backup mysql database using mysql dump?

Question

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1. Getting 0KB of size file while backup mysql database using mysql dump

2. Using PHP script: why mysqldump does not dump sql file?

3. Mysql PHP backup database using mysqldump

I want to Full database mysql (store procedure + table + trigger ) i try to code then not get any error but 0 kb database Download

I connect Mysql CMD Got Error like this

MYSqldump:Got error:2003 : can't connect to Mysql Server '172.30.70.54' <10060> when trying to connect

Cmd Code Execute

mysqldump  --user=root --password= --host=172.30.70.54 dv-admin > db_backup5.sql 

Php Script

<?php
    $dbhost = '172.30.70.54';
    $dbuser = 'root';
    $dbpass = 'mypass';
    $dbname='mydb';
    $toDay = date('d-m-Y');
    shell_exec("mysqldump --opt --routines -h$dbhost -u$dbuser -p$dbpass --single-transaction $dbname  > db_backup.sql");
    system("mysqldump -opt -routines -h$dbhost -u$dbuser -p$dbpass -single-transaction $dbname  > db_backup2.sql");
    ?>