drkdidel.be

MySQL: "ERROR 1005 (HY000): Can't create table ... (errno: 150)"

There can be a few reasons for this very helpful message. In my case, MySQL's default engine on the production server was MyISAM, while being InnoDB on the development server.

MyISAM does not handle foreign keys, thus the above error. The simple fix is to switch engines:

mysql> ALTER TABLE tableName ENGINE = InnoDB;

Execute a local bash script through SSH

Before this blessed day, I lost my time copying my bash scripts on the remote machines where I wanted to execute them through the ssh command. Until now, when I discovered that it is not necessary, thanks to the bash -s flag.

$ ssh user@remote 'bash -s'

Source

Linux/Windows: generate a SSH key for the http (Apache) user

I recently added a feature to a PHP web application, requiring to run an independent bash script, which connects remotely to another machine through SSH.

When I tested the bash script in command line, it was running with my credentials and used my ~/.ssh/id_rsa.pub to authenticate itself to the remote machine. But when the script was launched by PHP, itself launched by Apache, those credentials were not available. I tried ssh -i but obviously (everything seems logical afterwards ;-) it couldn't use my private key.

The solution is to have Apache create its own private/public key pair:

$ sudo -u http ssh-keygen -t rsa
$ sudo -u http ssh-copy-id username@servername

We use sudo -u to execute ssh-keygen as http user. On Arch Linux, this is the "name" of Apache. It may be different on your system.

Source

On Windows Server, Apache runs by default as NT_AUTHORITY/SYSTEM. The trick here is to run it under another existing user account. To set that option, open Administrative Tools > Services. In the Services window, select Apache2.x > right click > Properties > Log On tab > check "This account" and enter/browse the account of your choice (or create one first) > Apply and restart the service:

Git: edit a tag

Beware that this command change the original tag's date. To edit a tag called tagName:

$ git tag tagName tagName -f -m "new message"

Source

CSS: make a container wrap around its floating children

When an element contains floating elements, its height does not include the height of the floating elements because they are outside the natural flow of the document. To make the container aware of all the heights inside it, we can use the overflow property:

HTML:
<p>
    <a class="floatRight">I am floating!</a>
</p>

CSS:
p {
    overflow:auto;
}
a.floatRight {
    float:right;
}