Technically, this is a bash cheat sheet; however, many of the commands will work with Bourne shell descendants, such as zsh.

When you press ctrl+r in the shell, you activate a feature called “reverse-i-search.” Reverse-i-search’ing lets you search through your shell history commands, from most recent to oldest.

Run this line in your Bash console:

env x='() { :;}; echo vulnerable' bash -c "only this line should appear"

If you see this, your Bash is vulnerable to Heartbleed:

vulnerable
only this line should appear

If you see this, your Bash is secure from Heartbleed:

only this line should appear

I wanted to export my Safari Reading List on OS X, so I wrote some code to do it. I leveraged Ruby, but this methodology could be easily ported to other languages like Bash, Python, or Objective C.

In the ruby file:

#!/usr/bin/env ruby
puts 'Hello world'

At the command line:

chmod +x ruby.rb

Then you can execute it like this:

./ruby.rb

Often as part of an hourly, daily, or weekly server backup bash script, you will wish to dump all MySQL databases to disk as a gzip file. This way, in the case that any of your databases suffer from corruption or user error, you will have a backup.

Simply put this command inside your cron-scheduled backup bash script, substituting the USERNAME, PASSWORD, and the destination path with your info:

#!/bin/bash
mysqldump -u USERNAME -pPASSWORD --all-databases --routines| gzip > /mysqlbackups/MySQLDB_`date '+%m-%d-%Y'`.sql.gz

Use launchd. Do not use cron on OS X.

Source: the launchd man page.

If you run ls on a file or folder in OS X…

ls -la /dir/to/some_file_or_folder

You may see a permission entry like this:

-rwxr--r--@  1 john  admins   548 Oct 29 15:58 filename.plist

The at sign (@) means that the file has “extended attributes”. Extended attributes are basically some metadata that OS X and OS X apps can tack on to a file.

To view the extended attributes of a file, type:

xattr -l ./filename.ext

If you make a custom bash script in OS X, and you want everyone on the system to be able to access it, this is the directory where you should save it:

/usr/local/bin