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