chris.charabaruk.comCode For Life - Delicious software, I must write it.

Welcome, guest! Login Delicious software, I must write it. Code for Life About Portfolio Updating a Git branch without first checking it out If you work with multiple developers all pushing and pulling into a single remote Git repository, you know about outdated branches. Regular pull-and-rebase operations can become quite annoying. What’s worse is when you add feature branches into the mix, though. If you need to rebase feature branches before merging, keeping your main branch up to date can be painful. However, it doesn’t have to be! git pull only updates the current branch from a remote repository. Using it means having to go through a number of steps: Check out the main branch, pull updates, check out the feature branch, merge. Fortunately, it’s not the only way to update a branch. We can fetch all the commits from our remote repository and use one of Git’s plumbing commands to avoid the mess of multiple checkouts. And so long as your main branch has no local-only commits, it’s perfectly safe to do. Given a branch develop and a remote repository origin , we can update our local branch to point at the same commit as the remote branch like so: $ git fetch all $ git update-ref refs/heads/develop refs/remotes/origin/develop As a developer, you should be well aware of what git fetch does, but you might not have encountered update-ref before. Fortunately, it’s quite self-explanatory: the update-ref command simply moves the named reference to the specified commit. If you specify another reference instead, it will find the related commit and use that as the target of the updated reference. Since Git branches are just automatically-updated head references, this one update-ref command is all you need. You can easily set this up as a Git alias as well: update-branch = "!f() { git update-ref refs/heads/$1 refs/remotes/origin/$1; }; f" We need to use a shell function in order to get parameters in our alias. That lets us expand this out further, though. The function can check if the branch exists, and we can parameterize the remote name (with a default value, too). I’ll leave that as an exercise to the reader, however, since this isn’t a lesson on shell scripting. Posted on June 21, 2017 by Chris Charabaruk in Coding , Tech Tags: Git , hacks , version control social_news_624 https://chris.charabaruk.com/2017/06/update-git-branch-without-checkout/ Updating a Git branch without first checking it out 0 Automated ssh-agent locking with Win32-OpenSSH For the last two years, a PowerShell team at Microsoft have been working hard to bring OpenSSH into the world of Windows. As part of this process, their Win32-OpenSSH port turns both sshd and ssh-agent into native Windows services. For all these changes, though, some things just remain the same. Like on other platforms, ssh-agent doesn’t lock or remove stored identities when you lock the computer. And as a service, now it doesn’t even remove them when you log out! Fortunately, Windows Scheduled Tasks comes to our rescue. The XML document below is a Scheduled Tasks document which automatically locks ssh-agent whenever you log out or lock the computer. It should also do its thing when the computer goes to sleep or shuts down (don’t quote me on that). You can’t import the task as-is, but with a few minor adjustments you can start resting easy about ssh-agent in Windows. To use this task, first copy the contents of this file into your favourite text editor. You need to replace every instance of MACHINENAMEUserAccount with your machine/user name. If you run Windows 10, you can run whoami to get this info. You also need to replace MY_USER_SID with your SID, a semi-numeric identifier for your user account. It’s a bit more complicated so you might want to read this article to figure it out. If instead of locking your identities you want ssh-agent to delete them, also change the Actions/Exec/Arguments tag value to -D . UPDATE (22 June 2017): It turns out that locking ssh-agent prompts for a password when locking, which you can’t enter when you lock the computer. For now, the only option is to use the -D argument. Hopefully Win32-OpenSSH will support locking with Windows credentials in the near future. Finally, save the file as LockSshAgent.xml (or some other name), then import it in Task Scheduler. If you haven’t yet seen Win32-OpenSSH, you can give it a try with Chocolatey (install the openssh package ), or just run the universal installer by Darwin Sanoy. Make sure to use the /SSHAgentFeature flag in order to install ssh-agent . Alternatively, if you’d like to run an SSH server on your computer, use /SSHServerFeature instead (it includes ssh-agent by default). Posted on June 20, 2017 by Chris Charabaruk in Tech Tags: hacks , OpenSSH , ssh-agent , Windows social_news_625 https://chris.charabaruk.com/2017/06/automated-ssh-agent-locking-win32-openssh/ Automated ssh-agent locking with Win32-OpenSSH 0 Pivoting Caesar Cipher: a toy encryption algorithm English: Caesar cipher with a shift of 3. (Photo credit: Wikipedia) As a fun little exercise, I decided I wanted to come up with an encryption algorithm. It’s nothing new, but it was enjoyable as a bit of a time-waster. In this exercise, I’ve come up with a variation on the classic Caesar cipher (also known as ROT-13 ), where we shift characters a certain amount in order to mask our cleartext. However, unlike in ROT-13, we’re not going to use a fixed shift value. Instead, we’re going to establish particular characters—pivots—that cause the shift value to change for later characters in the message. The idea for this is that it will make it more difficult for an attacker to read the message, as they’d need to know which characters change the shift value, and how the value changes at each of those characters. There are two different ways we can approach the shift change: either by setting a new shift value outright, or by adjusting the existing shift value by adding or subtracting a value. We’ll go with the latter for this algorithm. Besides adding pivot points and a changing shift value, let’s also define a range of valid characters that can be used for encryption. Caesar’s cipher was designed with only the basic Latin characters in use at the time, but these days there are more characters in the Latin alphabet, not to mention our use of Indo-Arabic numerals. For our example, we’ll use an alphabet” of A-Z, 0-9, and the period / full stop for a total of 37 characters: ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 . We could add more characters (additional punctuation, space, accented characters, etc.) but this should be good enough for most uses of such a simple cipher. Not to mention that 37 is a prime number , which may offer us some useful characteristics. Since we’ve got into the example zone, let’s also set up our pivot points and their adjustment values. We’ll choose the vowels, the digit 0, and the full stop as our pivots, and the first seven primes as the shift adjustment values: Character Adjustment Character Adjustment A 2 U 11 E 3 0 13 I 5 . 17 O 7 Finally, we’ll choose an initial shift value. Remembering this system’s roots with the Caesar cipher, where we rotate by half the alphabet, we’ll choose 19, rounding to the odd number, coincidentally another prime number and the one that follows our final pivot point! We want to encrypt the message The password is swordfish.” First, of course, we’ll make it uppercase since our alphabet doesn’t have any lower case characters. Then we’ll replace the spaces with periods, and the period at the end with two periods so we know it’s the end of the sentence. Our resulting message for encryption is:THE.PASSWORD.IS.SWORDFISH.. ” The first character of the message is T with position 20 in the alphabet (remember, it’s indexed from 1, not 0), and our initial shift value is 19. The sum is 39, and as that’s greater than the length of our alphabet, we have to take the modulus, or 2. Therefore, our ciphertext starts with B. The next character, H,...