# Practical Git Tips and Tricks *** or *** ## How I learned to stop worrying, ## and love `git revert` .small[ Presented by [Edward Delaporte](mailto:edward.delaporte@busey.com) for [Busey Bank](https://www.busey.com) at [University of Illinois IT Professionals Forum](https://www.itproforum.illinois.edu/) on Nov 7, 2019. ] This slide deck is online at http://edward.delaporte.us ??? - Peter Sellers would have loved Git. - Git is elegant. - Git is often nonsensical. Edward - Team of 10 software developers - Team across 4 cities (Champaign, Decatur, Blomington, St. Louis) - Support 120 products that move money. - We move about 1/2 million per day - Payment Card Industry - Financial Sector Regulations - 100% code review shop - All developers take extensive security training - Everything is audited - Out of date JavaScript libs end up on the desk of the EVP of Risk and Compliance who reports to our CEO --- # Topics 1. Taking stock with `git status` and `git diff` 2. Undo 3. The sometimes surprising results of `git revert` 4. Frequently Asked Questions - Answered. 5. Pretty tools --- # Taking Stock *Where am I?* >git status *What have I done?* >git diff *What am I about to commit?* >git diff --cached ??? - Visual tools and `git diff` are a great way to take stock. - Most visual editors will have a right-click way to see git diff --cached - If you see two separate threads of work in git diff --cached, it is time to check some work in. Git Status - think of an empty `git status` as a home base - return to it often. - Anything in git status is an unresolved future problem - untracked files not in gitignore - unpushed or unpulled commits --- ## Undo *That was a stupid change.* >git reset HEAD .\ITProForum2019Spring.html *Well that was a stupid commit.* >git revert {commit hash} ??? --- # Sometimes Surprising Results of Git Revert ## git commit {first commit} <img class='stretch left little' src='img/itpro2019fall/Trees1.PNG'/> ## git commit {second commit} <img class='stretch little' src='img/itpro2019fall/Trees2_Expected.PNG'/> --- # Sometimes Surprising Results of Git Revert ## git commit {third commit} <img class='stretch left little' src='img/itpro2019fall/Trees3.PNG'/> ## git revert {third commit} <img class='stretch little' src='img/itpro2019fall/Trees2_Expected.PNG'/> ??? - As expected, we went back in time to a previous state. + The Revert Revert pattern - today's stupid mistake is tomorrow's 'good enough' --- # Sometimes Surprising Results of Git Revert ## git commit {third commit} <img class='stretch left little' src='img/itpro2019fall/Trees3.PNG'/> ## git revert { second commit } <img class='stretch little' src='img/itpro2019fall/Trees2.PNG'/> ??? - Surprise - this state has never existed in history. --- # Your Questions *What is the difference between `revert` and `reset`?* ## Revert - Will *not* lose your work. - Acts *on* a commit. - Supports the 'Revert Revert' pattern, that I love. ## Reset - Takes you *to* a commit. - Often *throws away* work! - Can help you lie about what you actually did to get here. ??? - when in doubt, use git revert - reset can lose work, revert cannot. - discuss the value of the revert a revert pattern - when do we git reset? when our commit is being sent to Google or Facebook. - Revert acts *ON* a commit. - Reset acts *TO* a commit. --- # Your Questions *Someone checked in and published a password.* - Change the password. ??? - History is impractical to change. - The Internet Way back Machine exists, even if you did change it. - Evil web crawler bots are looking for passwords, and they work fast. - They may have already harvested it. --- # Your Questions *How to fix a merge that contained incorrect files.* - If it went really badly, throw away your local (merge) branch and fix the original branches. - Otherwise, use the git tools to review and make correction, and commit the corrections. - Copy/Paste is your friend. --- # Your Questions *Testing/writing code in different branches that use common local files.* - Merge from your friend's branches early and often. - Ignore your enemies' branches. - Merge from `develop` and `master` early and often. - Submit pull requests earlier and more often. - No one rejects a pull request for being too easy to review. --- # Your Questions *Letting different machines fall out of sync with origin and trying to merge work cleanly.* - Start with `git pull` - Use branches to experiment. Throw them away if they don't work. - Copy/Paste is your friend. --- # Your Questions *Removing accidentally-checked in files from repos, without deleting them locally.* > git rm --cached .\BadFile.txt ??? - You won't remember this next slide, - but you will remember that Copy/Paste is your friend. --- # Your Questions *How do I keep these two branches separate forever?* > Separate the repositories. Everything in every branch is destined for master. ??? Separate branches forever? - Think of branches as streams flowing together to become rivers. - Anything you drop into any stream will someday reach the ocean (master branch). --- # Your Questions *I know what I want the final files to look like, but not how to get it there in git?* > Copy/Paste is your friend. ??? Why is copy/paste great? - Just make it right. - Your history will show you got lost, and forced it right. That has value. --- # Pretty Tools [Tortoise Git](https://tortoisegit.org/) - Add right-click menu items to Windows Explorer - Like TortoiseSvn, but for Git Atlassian SourceTree - [Atlassian SourceTree for Mac and Windows](https://www.sourcetreeapp.com/) GitHub Desktop - [GitHub Desktop](https://desktop.github.com/) ??? Tortoise - Right click can be fun SourceTree - Point and click your way through Git history - Visual branch/merge history - See past revisions - Diff between arbitrary revisions - Manage branches and branch operations in a visual way --- # Pretty Tools Visual Studio Code - [Free/Open/Cross Platform from Microsoft](https://code.visualstudio.com/) - [GitLens Plugin](https://github.com/eamodio/vscode-gitlens/tree/master/#code-lens-) - Other great plugins include: VsVim, RainbowCSV, Markdown Paste, Markdown PDF ??? VSCode - VsCode Handles git out of the box. - Searching Git in the plugin marketplace returned 5 pages of results. - Code Lens - see who changed which line last - Various visual ways to explore history - Native integrated shell --- ## Discussion - This slide deck is online at http://Edward.Delaporte.us - Need more git? Advanced Git session is after the break. ??? - You can find this slide deck at Edward.Delaporte.us --- # BONUS SLIDES --- # Git INIT *I need a git server, but all I have is a Windows file share.* >cd \\remote\share\folder.git\ >git init --bare ??? + using a Windows folder like any other remote --- ## Can I do better at staging my un-commited work? `git add --interactive` ```powershell *** Commands *** 1: status 2: update 3: revert 4: add untracked 5: patch 6: diff 7: quit 8: help What now> p staged unstaged path 1: unchanged +4/-0 ITProForum2019Spring.html Patch update>> diff --git a/ITProForum2019Spring.html b/ITProForum2019Spring.html index 6a58513..323781d 100644 --- a/ITProForum2019Spring.html +++ b/ITProForum2019Spring.html @@ -108,6 +108,10 @@ Slide Count: >git diff +*Can I do better at staging my un-commited work?* + +>git add --interactive Stage this hunk [y,n,q,a,d,e,?]? ``` ??? + Yes. You can. + Not as scary as it looks here. + Giving it a try can give you an idea of the possibilities. + You can point and click to get this effect too. --- ## How did line 9 of this file become so strange? `git log -L` ```powershell PS C:\Users\edthe\edthedev.github.io> git log -L 7,10:index.html ``` ```powershell commit 4443e18da5c5729bdb8b7251dda5a8bb46b698a3 Author: EdTheDev <edward@delaporte.us> Date: Mon Jun 3 21:23:45 2019 -0500 Move presentations into more recent format diff --git a/index.html b/index.html --- a/index.html +++ b/index.html @@ -7,4 +7,4 @@ <body> <div class="bootmark" -data-src="Welcome.md Microbit.md Robobrawl.md Learn2Code.md Footer.md" +data-src="Welcome.md presentations.md Microbit.md Robobrawl.md Learn2Code.md Footer.md" data-join="---" commit 8a76e94d789cc20c8b24987b94275462382b4acb Author: EdTheDev <edward@delaporte.us> Date: Wed Apr 3 20:47:48 2019 -0500 Change up the order a bit. ...more of same from above... ``` --- ## Who decided line 9 should be strange?! `git blame` ```powershell PS C:\Users\edthe\edthedev.github.io> git blame .\index.html ``` ```powershell 3cbc7b3a (Edward Delaporte 2015-07-25 11:45:35 -0500 1) <!DOCTYPE html> 3cbc7b3a (Edward Delaporte 2015-07-25 11:45:35 -0500 2) <html> e2e4117f (Edward Delaporte 2017-05-06 00:37:46 +0000 3) <head> e2e4117f (Edward Delaporte 2017-05-06 00:37:46 +0000 4) <link rel="stylesheet" href="static/edthedev.css" /> e2e4117f (Edward Delaporte 2017-05-06 00:37:46 +0000 5) <script src="static/bootmark.min.js"></script> e2e4117f (Edward Delaporte 2017-05-06 00:37:46 +0000 6) </head> e2e4117f (Edward Delaporte 2017-05-06 00:37:46 +0000 7) <body> 4bf3f64c (Edward Delaporte 2017-05-06 05:10:05 +0000 8) <div class="bootmark" 4443e18d (EdTheDev 2019-06-03 21:23:45 -0500 9) data-src="Welcome.md presentations.md Microbit.md Robobrawl.md Learn2Code.md Footer.md" 4bf3f64c (Edward Delaporte 2017-05-06 05:10:05 +0000 10) data-join="---" 4bf3f64c (Edward Delaporte 2017-05-06 05:10:05 +0000 11) ></div> 7cf65857 (Edward Delaporte 2015-07-25 12:19:15 -0500 12) </body> 3cbc7b3a (Edward Delaporte 2015-07-25 11:45:35 -0500 13) </html> ``` ??? + Each line of the file. + Who last modified each line. + When last modified each line. --- ## How to protect `master` ``` #!/bin/sh branch="$(git rev-parse --abbrev-ref HEAD)" (At the repo) Create file .git/hooks/pre-commit with following content: if [ "$branch" = "master" ]; then echo "You can't commit directly to master branch" exit 1 fi ``` Make it executable (not required on Windows): ``` $ chmod +x .git/hooks/pre-commit ``` [Full solution at Stack Overflow][10] [10]: https://stackoverflow.com/questions/40462111/git-prevent-commits-in-master-branch ??? + Git hooks are just shell scripts. + You can and should do more with them. + You can make your chat bot cuss out whoever broke the build or forgot to comment. --- ## What else can `git diff` do? [Quite a bit][2] [2]: https://git-scm.com/docs/git-diff ``` git diff [<options>] [<commit>] [--] [<path>…​] git diff [<options>] --cached [<commit>] [--] [<path>…​] git diff [<options>] <commit> <commit> [--] [<path>…​] git diff [<options>] <blob> <blob> git diff [<options>] --no-index [--] <path> <path> ``` ??? - Diff can do more - but the default target is the last commit