[comment]: # "markdown: { smartypants: true }" Warning: Live Editing Part 1.5 of 3 --- ## Interactive Shell # vs ## Scripting --- ## Interactive Shell --- ## Scripting --- **Posix Shell** (Scripting) --- The _NOT_-Bash Parts (Learn to *Un*learn) --- ## Part 1.5 Continued --- # TREL --- - **T**ry - **R**ead (what's on the screen) - **E**valuate (with your human brain) - **L**oop (back to try again) --- The equal and opposite of the REPL. <small>(the human loop between your fingers, the screen, and your brain)</small> --- # REPL --- - **R**ead (from the keyboard) - **E**valuate (syntax and expressions) - **P**rint (the error or result) - **L**oop --- There is no magic. <small>(the computer does what you say, not what you <em>want</em>)</small> --- ## 0. Pre-req Prep work for upcoming exercises. --- ### 0.1 Webi Make sure [`webi`](https://webinstall.dev/webi) is installed. ```sh curl -sS https://webi.sh/ | sh ``` --- ### 0.2 Friendly, Interactive Shell 1. Get back into [`fish`](https://webinstall.dev/fish) ```sh fish ``` 2. _If_ that fails ```sh webi fish ``` 3. TREL. And try again. --- ### 0.3 Vim Essentials 1. Install [`node`](https://webinstall.dev/node) for [`prettier`](https://webinstall.dev/prettier) (code formatter) ```sh webi node node --version pathman add ~/.local/opt/node/bin node --version webi prettier ``` 2. Install [`vim-essentials`](https://webinstall.dev/vim-essentials) (formatters & linters) ```sh webi shfmt shellcheck webi vim-essentials ``` --- ### 0.4 Command Line Utilities [`aliasman`](https://webinstall.dev/aliasman), [`bat`](https://webinstall.dev/bat), [`curlie`](https://webinstall.dev/curlie), [`jq`](https://webinstall.dev/jq) ```sh webi aliasman bat curlie jq ``` ```md | `aliasman` | create aliases that work cross shells | | `bat` | `cat` (view) files with colors & paging | | `curlie` | wrap `curl` with syntax highlighting | | `jq` | query JSON files and APIs for specific data | ``` --- ### 0.4 Temp Directory Go to a place we can make junk files. ```sh pwd ``` ```sh pushd /tmp/ pwd ``` ```sh popd pwd ``` ```sh pushd /tmp/ ``` --- ## Interactive Shell (Continued) --- ### Big Goal Automate, Test and Debug tasks in Terminal 0. Eratta 1. Auto-complete 2. Text Navigation 3. Variables 4. Pipes 5. & Redirection --- ## 0. Eratta <kbd>Ctrl ⌃</kbd> + <kbd>s</kbd> - This is called "scroll lock". - It freezes _some_ shells (`bash`, `sh`), \ but not all (e.g. `fish`) <small>(nor any shell spawned from fish)</small> --- Try in a terminal or console \ where `bash` is the parent shell: ```sh find / ``` <kbd>Ctrl ⌃</kbd> + <kbd>s</kbd> <kbd>Ctrl ⌃</kbd> + <kbd>q</kbd> --- ## 1. Autocomplete Goals Avoid typos by avoiding typing. > use the tools, Luke --- ### 1.1 Just TREL ⬆️ ➡️ 🎩 <kbd>tab</kbd> 🪄 Try browsing your history \ (or just typing letters) \ and test the autocomplete. --- 11 out of 10 doctors agree: > Typing is the leading cause of typos --- ### 2. Navigation Goals Learn keyboard navigation. - emacs-style (line) - vim-style (text) --- ### 2.1 Start & End (of Line) | | | | -------------------------------- | ------------------------------------- | | <kbd>Ctrl ⌃</kbd> + <kbd>a</kbd> | for start (of alphabet), leftmost key | | <kbd>Ctrl ⌃</kbd> + <kbd>e</kbd> | for 'end' | | | | <small>(fyi: these come from emacs, but are nearly-universally supported)</small> --- ### 2.1.1 Exercise ```sh # type out this line (alias 'setalias' as 'aliasman') alias setalias='aliasman' # but instead of typing this out: # 1. hit Up to see the previous line # 2. use Ctrl ⌃ + a to move to the start of the line # 3. add 'set' in front of 'alias' # 4. use Ctrl ⌃ + e to get back to the end of the line # 5. hit Enter ⏎ to run it setalias setalias='aliasman' ``` <small>(note<span>:</span> the output will tell you to run `alias`, but you've already done that)</small> --- Repeat for muscle memory! ```sh # make our interactive `cat` a colorful `bat` alias cat='bat --style=plain --pager=none' setalias cat='bat --style=plain --pager=none' ``` Feel the burn! ```sh # give our interactive `curl` colors alias curl='curlie' setalias curl='curlie' ``` --- ### 2.2 Text Navigation 🔝🇬 ⬅️🇭⬇️🇯⬆️🇰➡️🇱 ⏭️🇳 --- | <kbd>Shift ⇧</kbd> | 🔄 | does the opposite or extreme | | ------------------ | --- | ------------------------------- | | <br> | | | | `gg`, `G` | 🔝 | **g**ood **g**ame # 1, opposite | | `hjkl` | 📈 | awesome goes up to the right | | `n`, `N` | ⏭️ | **n**ext result, opposite | --- ### 2.2.1 Exercise Let's pick a file with a few dozen lines... ```sh vim ~/.vimrc ``` (updated by [`vim-essentials`](https://webinstall.dev/vim-essentials)) --- 🎗️Reminder | <kbd>esc</kbd>, `:q!` | quit (immediately) | | --------------------- | ------------------ | | `/` | search | | <kbd>esc</kbd>, `:w` | write (save) | --- 1. Go to the top and bottom ```sh gg # top of file G # (the opposite) ``` 2. Go all the way... 📈🇭🇯🇰🇱 ```sh h # left j # down k # up l # right ``` 3. Search `/` for "the" ```sh n # next result N # (the opposite) ``` --- Repeat - build your muscle memory. Also, try [Vim Adventures](https://vim-adventures.com/). --- ℹ️ vim-style text navigation works in _many_ places as we'll see shortly 😉 --- ## 3. Variables Goals Learn to diagnose unexpected results (quotes, variables, and interpolation) --- ### 3.1 TREL Exercise 1. What do you think this will output? ```sh echo It's $100 bills y'all ``` 2. Try it. 3. Is anything different what what you thought? --- 1. What's different about this? ```sh echo "It's $100 bills y'all" ``` 2. What will it do differently? 3. Try it. 4. Is anything different what what you thought? --- What about each of these? (keep practicing <kbd>Ctrl ⌃</kbd> + <kbd>a</kbd> and <kbd>Ctrl ⌃</kbd> + <kbd>e</kbd>) ```sh echo It\'s $100 bills y\'all echo 'It\'s $100 bills y\'all' echo "It's \$100 bills y'all" echo \"It's \$100 bills y'all\" ``` --- ### 3.2 Interactive Variables - In general: - variables last until you exit the shell - In `fish`: - we declare variables like: `export foo='bar'` \ (in scripting we'll rarely need `export`) - we access it as `$foo` rather than `${foo}` \ (in scripts `${foo}` is more correct) --- The file I wanted you to download: ```sh https://raw.githubusercontent.com/BeyondCodeBootcamp/shell-cheatsheet/main/README.md ``` Too long to fit on a slide! (time to learn about variables!) --- Download the url to NOTES.md ```sh # 1. Declare a variable (interactive shell syntax) # (note the single quotes) export my_url='https://raw.githubusercontent.com' # 2. Add more to that variable # (note the double quotes) export my_url="$my_url/BeyondCodeBootcamp/shell-cheatsheet" export my_url="$my_url/main/README.md" # 3. Download using the variable (interactive shell syntax) # (note the double quotes, again) curl -o ./NOTES.md \ "$my_url" ``` (still in `/tmp`) --- Recap of variables in `fish`: ```sh # declare a variable export foo='bar' # read a variable echo "foo is $foo" # don't read a variable echo 'foo is $foo' # escape a variable echo "escaping '\$foo'" # all together now echo "the value of \$foo is '$foo'" ``` (but in scripts we'll use `${foo}`) --- ### 4. File & Pager Goals - What's plain text? - What's a pager? - Why are there _sometimes_ colors? --- ### 4.1 TREL Exercise What are the differences and similarities of each? \ unix `cat`, `cat` (the alias), `bat`, & `less` ```sh /bin/cat ./NOTES.md cat ./NOTES.md less ./NOTES.md bat ./NOTES.md ``` (and `q` to quit, just like `vim`) --- Cleanup time! ```sh # rm to remove (delete) rm ./NOTES.md cat ./NOTES.md ``` --- ### 5. Pipes & Redirection Goals Understand how commands use inputs and outputs (in Uinx everything is _like_ a file) --- | Director | Description | | :------------------- | :----------------------------- | | `>` | **replace** file with _stdout_ | | `>>` | append _stdout_ to file | | `2>` | _stderr_ to file | | <code>\|</code> | _stdout_ to _stdin_ | | `<` | _stdin_ from file | --- ### 5.1 TREL Exercise --- What are the differences and similarities: \ reading from a file? reading from a pipe? ```sh curl "$my_url" curl "$my_url" | bat curl "$my_url" | less curl "$my_url" \ > ./NOTES.md bat ./NOTES.md ``` --- Have you checked out [example.com](https://example.com)? \ It's a _real_ website! ```sh # pipe example.com to bat curl https://example.com | bat # write curl's output to index.html curl https://example.com > index.html # pipe index.html into bat bat < index.html ``` --- How are these different? ```sh curl -o index.html https://example.com curl https://example.com > index.html ``` Hint: you can run a program _without_ a shell --- How are these different? ```sh bat index.html bat < index.html ``` --- Why isn't _all_ of the output in the file? ```sh curl "$my_url" \ > ./NOTES.md \ 2> ./log.txt bat ./log.txt ``` --- > Programs can detect whether they're reading a file, or from a pipe (or stdin). --- ```sh export my_url='https://api.github.com/search/issues' export my_url="$my_url?q=type:pr+state:closed" export my_url="$my_url+author:coolaj86" export my_url="$my_url&per_page=2&page=1" ``` ```sh curl "$my_url" curl "$my_url" > \ ./gh-issues.json ``` --- ```sh bat ./gh-issues.json bat < ./gh-issues.json bat ./gh-issues.json | jq '.' cat ./gh-issues.json | jq '.total_count' jq '.total_count' < ./gh-issues.json ``` --- ```sh jq '.items' < ./gh-issues.json jq '.items[]' < ./gh-issues.json jq '.items[0]' < ./gh-issues.json jq '.items[].url' < ./gh-issues.json jq '.items[0].url' < ./gh-issues.json ```