Why is the archive not being created?

Question

linux

On the hosting, a copy of the files and site database is created using the system () commands;
Code snippet:

$cmd = "cd ".$this->getProjectDir()."/folders && tar rvf public_html.tar ".$dir['public_html'];
system($cmd, $ret);
$cmd = "cd ".$this->getProjectDir()." && find . -type f -exec tar rvf ".$this->archive.".tar '{}' \;";
system($cmd, $ret);
$cmd = "cd ".$this->getProjectDir()." && gzip ".$this->archive.".tar";
system($cmd, $ret);

Everything goes fine, but the archive turns out to be "broken" - when unzipping, an error occurs
2017-05-08-1494256895.tar.gz: Unexpected end of archive
The script itself works completely, possible limits on execution time and memory are increased.
What could be the reason for this failure?

Answer 1

try to make an archive in the terminal without PHP - will it be the same?