Here are some commands for starting/stopping/restarting apache/httpd service via Linux command shell/SSH

On Linux CentOS:

/sbin/service httpd start
/sbin/service httpd stop
/sbin/service httpd restart

On Linux RHEL / CentOS/ Fedora:

service httpd start
service httpd stop
service httpd restart

On other Unix/Linux environment:

/etc/init.d/apache2 start
/etc/init.d/apache2 stop
/etc/init.d/apache2 restart