Peter Mescalchin magnetikonline

Bash if conditions with functions()

Some examples of calling bash functions in if; then; fi conditionals - both functions that echo and return.

#!/bin/bash -e

function functionOne {
	echo -n "$1 - $2"
}

Install OSX Parallels version 10/11/12/13 tools on Ubuntu server guest

Have tested these instructions successfully under Ubuntu 16.04LTS and 14.04LTS.

Create Ubuntu server instance under Parallels (obviously).
Start VM, goto Actions - Install Parallels Tools... to mount the ISO image.
- Note: if this fails, or updating tools for an existing guest you can do the following:
- Goto Devices > CD/DVD 1 > Connect Image....
- Select the following ISO image: /Applications/Parallels Desktop/Contents/Resources/Tools/prl-tools-lin.iso.
- This will mount the tools CD image.

Transfer MySQL databases between AWS RDS instances

The situation

Two AWS RDS MySQL databases - moving databases from source to destination.
Both databases are not publicly accessible, only via an EC2 instance(s) - e.g. you have setup your security groups.
Can SSH to a target EC2 instance (but of course).

What it does

Sets up two SSH port forwards on local machine - one to source database, another to target.
Via calls to transferDatabase():

Using BFG to clean out old binary assets from Git repository

Reference: http://rtyley.github.io/bfg-repo-cleaner/

Example

$ wget http://repo1.maven.org/maven2/com/madgag/bfg/1.11.8/bfg-1.11.8.jar
$ git clone git@github.com:org-name/repo-name.git repo-name.cleanup
$ java -jar bfg-1.11.8.jar --delete-files '*.{gif,jpg,png}' repo-name.cleanup
$ cd repo-name.cleanup
$ git gc --prune=now --aggressive

AWS CLI S3 usage examples

Local dir to remote bucket sync
Local dir to remote bucket copy with gzip content encoding header
Remote to remote bucket copy

Local dir to remote bucket sync

$ aws s3 sync \

Extract unique HTTP request lines from access.log

$ cat access.log \
	| grep "] \"GET /wp-content/themes/" \
	| awk '{print $7}' \
	| sort -u

Ensure HTTP redirects are not cached

Chrome (at least) likes to cache HTTP redirects, an issue if you are running logging/reporting on those redirect actions server side. Combat this with some HTTP headers.

Location: http://domain.com/redirect
Cache-Control: must-revalidate,no-cache,no-store
Expires: Sat, 01 Jan 2000 00:00:00 GMT

Or in PHP land that could be...

	#!/bin/bash

	# query MySQL for slave replication status
	# note: requires [~/.my.cnf] to be present a populated with valid MySQL password
	mysql \
	--batch \
	--user root \
	--execute "SHOW GLOBAL STATUS LIKE 'Slave_running';" \| \
	tail --lines 1 \| grep --extended-regexp --quiet "^Slave_running\tON$"

	#!/bin/bash

	git clone --depth 1 \
	-qb $BRANCH_NAME \
	$REPOSITORY_URL $TARGET_CLONE_DIR
	cd $TARGET_CLONE_DIR
	git submodule update -q --init --depth 1

	#!/bin/bash

	find . -type f -exec touch -r "{}" -d '+1 day' "{}" \;