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PHP database can’t connect to localhost but works

There are many reasons for this, so first check that MySQL/MariaDB is running properly, that you are using the correct credentials and that the the appropriate user@localhost has access.

Also check you aren’t using skip-name-resolve and bind-address in your my.cnf file if accessing from outside of the localhost. These are things you will find with a google search.

Apart from this one other reason why will work and localhost will not work is if you are using something other than the default socket=/var/lib/mysql/mysql.sock location in your my.cnf.

If that is the case, you’ll need to update the relevant default_socket= parameter in php.ini (for each driver) to match that socket – see the entries under my.cnf [mysql] and [mysqld] sections for the socket parameter. This is more likely to occur if you are using MariaDB for example.

Command line grep

Here’s a pretty nice combination of parameters for command line grep using egrep (which supports regex):

egrep -rHnC1 "bprajb" .

This will search in the current directory recursively through all files that match the word “praj” (regex boundary b tags) and return the file name and context (1 line either side of the match) with line numbers.

For example here’s the resut with the matching word highlighted as well on the terminal.

MySQL compare strings by case

Here’s one method of comparing strings by case in MySQL. You can use the md5 function to hash the string and compare to its lower case value.

This example is for checking for usernames that are not lower case in moodle.

select username, md5(username), md5(lower(username))
from mdl_user
where deleted = 0 and suspended = 0
and md5(username) != md5(lower(username));

If the md5 hash when the string is lower cased is different to the current md5 hash you will get a result.

$_SESSION global is empty

If you find that your global $_SESSION variable is empty there can be several reasons, here are a few:

  • The session.save_path is invalid (does not exist) or is not writable.
  • The session.cookie_secure is set to true but you not using a secure site (SSL/https).
  • The session.cookie_domain is set to a domain that does not match your site – very common if setting up a dev or test environment from a production site with a public domain.

soapUI 5.x hangs on Mac OSX

I’ve had this issue on OSX Mavericks and Yosemite on soapUI 5.x versions. Here’s a fix that disables the browser in soapUI which seems to cause it to hang.

Open /Applications/ (adjust to suit your version).

Editvmoptions.txt and add line: -Dsoapui.browser.disabled=true

Open /Applications/ (adjust to suit your version)

Edit and uncomment line: -Dsoapui.browser.disabled=true

PHP Session Save Path

You can find the session.save_path through php info or using the command line:

php -i | grep save_path

E.g. /var/lib/php/session

Once you have that, you clear PHP sessions by going into that path and clearing out the relevation session files.

Escaping variables inside other variables in bash scripts

Say you have a variable that comprises of another variable like so:


The above won’t work as bash will interpret the underscore after $var_name as part of the variable name and look for a variable called $var_name_and_extension and not find it.

Two ways to solve this:

Enclose in curly braces as follows:


Use double quotes to delineate between the variable name and the string: