Syntax check
To check configuration files for syntax errors:
# Fedora, RHEL, CentOS, OSX
httpd -t
# Debian, Ubuntu
apache2ctl -t
# MacOS
apachectl -t
List virtual hosts
To list all virtual hosts, and their locations:
# Fedora, RHEL, CentOS, OSX
httpd -S
# Debian, Ubuntu
apache2ctl -S
# MacOS
apachectl -S