mdadm --create --verbose /dev/md1 --level=6 --raid-devices=4 /dev/sda2 /dev/sdb2 missing missing

apache: openssl rsa -in out.key -out out.key --strip the password, i.e. if take password-protected key and get rid of password protection.

ssl: openssl genrsa -des3 -out out.key 4096 &&openssl req -new -key out.key -out out.csr

apache: yum install mod_ssl

sendmail: define(RELAY_HOST, foobar.com)

apache: htpasswd -c /etc/httpd/htpasswd admin

apache: service httpd configtest

vi: e! ---reread the file losing all unsaved edits

bash -n ---parse for syntax errors. No commands are actually executed

sh: bash -x --show lines to be executed prior to their execution; -u --generate an error when Undefined variable is used.

sh: while : ; do echo "haha haha haha..."; sleep 1;done

stty -a