Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Create a new ext3 file system using LVM
Answer:
To create a new ext3 partition using the Logical Volume Manager (LVM) is just easy with a few commands:
# lvcreate -L 100G -n /dev/vg0/vp0 (Assume volume group is vg0)
# mkfs -t ext3 -m 1 -v /dev/vg0/vp0Then you can mount the /dev/vg0/vp0 as usual.
Add Personal Package Archives (PPA) to the current repository in Ubuntu
Answer:
add-apt-repository is a helper script which adds an external APT repository to either /etc/apt/sources.list or a file in /etc/apt/sources.list.d/. It can also import the keys needed.
To get this tool, just a single command:
# sudo apt-get install python-software-properties
That is it.
Why SSL cannot be used with name-based virtual hosts?
Answer:
The reason is pretty simple: If you are using a single IP but with many virtual hosts, each virtual hosts has their own certificate and private key. Without looking at the Host header in the incoming HTTP request, Apache will not be able to route the request to the designated virtual hosts. The core problem is, the incoming requests are encrypted so we are not able to tell which key should be used for decryption!
So only IP-based virtual hosts works if you need SSL.
How to format a JSON file using command line
Answer:
JSON (JavaScript Object Notation) is a very popular data exchange format nowadays and to pretty format (i.e. easy to read) a JSON file, you can use the following method:
# cat my.json | python -mjson.tool
That's all.
Dump the table schema of a MySQL database
Answer:
To dump the schema of a MySQL database (hence, no data), you need just one command:
E.g.
# mysqldump my_db my_table --no-data
