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+WEBVTT captioned by howard
+
+NOTE Introduction
+
+00:00:00.000 --> 00:00:04.999
+I have 10 minutes to talk you into
+
+00:00:05.000 --> 00:00:07.879
+giving Eshell a second chance.
+
+00:00:07.880 --> 00:00:10.119
+Have the right perspective and expectation,
+
+00:00:10.120 --> 00:00:12.919
+and I think you’ll really enjoy it.
+
+00:00:12.920 --> 00:00:15.679
+Just remember eshell is a shell,
+
+00:00:15.680 --> 00:00:17.839
+not a terminal emulator.
+
+00:00:17.840 --> 00:00:20.279
+I use both Eshell and vterm.
+
+00:00:20.280 --> 00:00:23.479
+I’m going to talk and type fast,
+
+00:00:23.480 --> 00:00:28.999
+as I have 10 reasons for you to try Eshell again.
+
+NOTE 1. It’s an Emacs REPL
+
+00:00:29.000 --> 00:00:32.599
+1. It’s an Emacs REPL.
+
+00:00:32.600 --> 00:00:33.999
+I mean, check this out.
+
+00:00:34.000 --> 00:00:36.999
+Let’s start up Eshell here.
+
+00:00:37.000 --> 00:00:41.399
+Let’s just type a Lisp expression.
+
+00:00:41.400 --> 00:00:43.919
+It works.
+
+00:00:43.920 --> 00:00:48.599
+As a shell, the parens are kinda optional.
+
+NOTE 2. It’s also a shell
+
+00:00:48.600 --> 00:00:52.519
+2. It’s also a shell.
+
+00:00:52.520 --> 00:00:56.479
+While eshell may look like a shell, like Bash
+
+00:00:56.480 --> 00:00:58.559
+you should view it as a REPL
+
+00:00:58.560 --> 00:01:02.399
+with parenthesis-less s-expressions.
+
+00:01:02.400 --> 00:01:05.559
+This makes sense, because a shell command with options,
+
+00:01:05.560 --> 00:01:07.999
+like this ls command,
+
+00:01:08.000 --> 00:01:10.119
+looks like an s-expression.
+
+NOTE 3. You can mix these two modes
+
+00:01:10.120 --> 00:01:12.879
+3. You can mix these two modes.
+
+00:01:12.880 --> 00:01:14.959
+Shells can call subshells
+
+00:01:14.960 --> 00:01:17.919
+which return their output like a function call,
+
+00:01:17.920 --> 00:01:20.799
+like this Bash command.
+
+00:01:20.800 --> 00:01:22.759
+In this Eshell example,
+
+00:01:22.760 --> 00:01:24.639
+I use the output of a text file
+
+00:01:24.640 --> 00:01:27.959
+as command line arguments to ripgrep.
+
+00:01:27.960 --> 00:01:29.639
+Notice how I use braces
+
+00:01:29.640 --> 00:01:34.759
+to state that it is a call to an eshell expression.
+
+00:01:34.760 --> 00:01:40.039
+We can mix Lisp-expressions and Shell-expressions.
+
+00:01:40.040 --> 00:01:45.599
+Allow me a contrived example.
+
+00:01:45.600 --> 00:01:50.079
+Notice I use good ol' setq to create a variable.
+
+00:01:50.080 --> 00:01:54.919
+Yes, those are global Emacs variables available everywhere.
+
+00:01:54.920 --> 00:01:59.599
+In Eshell, the wildcard actually creates a list.
+
+00:01:59.600 --> 00:02:04.479
+This variable assignment doesn’t work as you might expect,
+
+00:02:04.480 --> 00:02:07.559
+as setq in Eshell is still setq,
+
+00:02:07.560 --> 00:02:10.319
+and it assigns variables in pairs.
+
+00:02:10.320 --> 00:02:17.119
+To make a list in Eshell, we use listify:
+
+00:02:17.120 --> 00:02:21.239
+Without parens, Eshell is in “shell mode”,
+
+00:02:21.240 --> 00:02:23.799
+which means that words are strings,
+
+00:02:23.800 --> 00:02:26.879
+and variables need to be prefixed with dollar signs.
+
+00:02:26.880 --> 00:02:32.399
+A command can have both Eshell and Lisp expressions.
+
+00:02:32.400 --> 00:02:34.559
+As you can see here,
+
+00:02:34.560 --> 00:02:37.119
+I have a call to ripgrep,
+
+00:02:37.120 --> 00:02:40.319
+but part of it is an s-expression.
+
+00:02:40.320 --> 00:02:42.239
+Remember the differences:
+
+00:02:42.240 --> 00:02:46.159
+With parens, eshell treats it as Lisp,
+
+00:02:46.160 --> 00:02:49.199
+like the last line in my example.
+
+00:02:49.200 --> 00:02:53.919
+With braces, eshell follows these shell-like rules:
+
+00:02:53.920 --> 00:02:57.159
+First, if it looks like a number, it's a number.
+
+00:02:57.160 --> 00:02:59.439
+Otherwise, eshell converts it to a string
+
+00:02:59.440 --> 00:03:03.679
+(quotes, like a shell, groups words).
+
+00:03:03.680 --> 00:03:07.519
+What about this mix between functions and executables
+
+00:03:07.520 --> 00:03:10.839
+for the first word?
+
+00:03:10.840 --> 00:03:15.439
+Functions that begin with eshell are called first.
+
+00:03:15.440 --> 00:03:19.079
+Next in priority are executables on your $PATH,
+
+00:03:19.080 --> 00:03:22.159
+then matching Lisp functions.
+
+00:03:22.160 --> 00:03:23.940
+You can actually switch this order
+
+00:03:23.941 --> 00:03:27.559
+with the `eshell-prefer-lisp-functions` variable.
+
+NOTE 4. Emacs is better than shell
+
+00:03:27.560 --> 00:03:31.759
+4. Emacs is actually better than shell.
+
+00:03:31.760 --> 00:03:35.199
+If the following works, why would you call
+
+00:03:35.200 --> 00:03:40.039
+expr or bc or dc, or any of those other calculators?
+
+00:03:40.040 --> 00:03:43.639
+You can just call a Lisp expression.
+
+00:03:43.640 --> 00:03:47.999
+Why call less or more when you could call view-file?
+
+00:03:48.000 --> 00:03:52.839
+Here, I’ve aliased less to view-file.
+
+00:03:52.840 --> 00:03:57.559
+Load it up, and it shows up in an Emacs mode.
+
+00:03:57.560 --> 00:04:01.519
+Just like with less, if you hit q,
+
+00:04:01.520 --> 00:04:05.759
+you go back to your Eshell terminal.
+
+00:04:05.760 --> 00:04:08.439
+I do have an improvement, though.
+
+00:04:08.440 --> 00:04:10.479
+The problem with view-file is
+
+00:04:10.480 --> 00:04:13.399
+it takes a single file as an argument.
+
+00:04:13.400 --> 00:04:15.719
+In a shell, we might want to view more than one.
+
+00:04:15.720 --> 00:04:18.719
+So let’s make a solution to that.
+
+00:04:18.720 --> 00:04:20.999
+This function will call the first function
+
+00:04:21.000 --> 00:04:22.159
+with the first argument,
+
+00:04:22.160 --> 00:04:26.679
+and the second function with each of the rest.
+
+00:04:26.680 --> 00:04:29.559
+This allows me to make a version of less
+
+00:04:29.560 --> 00:04:33.159
+that calls view-file on the first [argument] given,
+
+00:04:33.160 --> 00:04:36.079
+but open in another window for each additional file.
+
+NOTE 5. Better regular expressions
+
+00:04:36.080 --> 00:04:41.239
+5. Better regular expressions.
+
+00:04:41.240 --> 00:04:44.799
+Can’t remember regular expressions when calling
+
+00:04:44.800 --> 00:04:48.639
+grep or some other search function? Use the rx macro.
+
+00:04:48.640 --> 00:04:55.919
+Here I call ripgrep again, but this time,
+
+00:04:55.920 --> 00:05:00.679
+I’m using a Lisp expression calling the rx macro
+
+00:05:00.680 --> 00:05:04.719
+to look for UUIDs in the files in my current directory.
+
+00:05:04.720 --> 00:05:08.159
+But I have another improvement for this.
+
+00:05:08.160 --> 00:05:13.479
+While the rx macro is freaking cool for Emacs Lisp,
+
+00:05:13.480 --> 00:05:15.919
+it doesn’t always translate to regular expressions
+
+00:05:15.920 --> 00:05:20.079
+accepted by most commands.
+
+00:05:20.080 --> 00:05:25.199
+The (I have no idea how to pronounce this) pcre2el project
+
+00:05:25.200 --> 00:05:28.519
+can convert from a Lisp regular expression
+
+00:05:28.520 --> 00:05:31.359
+to Perl-compatible regular expressions (PCRE)
+
+00:05:31.360 --> 00:05:33.519
+acceptable by most search commands.
+
+00:05:33.520 --> 00:05:37.879
+I’ve created a new macro here, prx,
+
+00:05:37.880 --> 00:05:41.319
+that translates the output of the rx macro.
+
+00:05:41.320 --> 00:05:46.519
+This allows me to type something much more readable,
+
+00:05:46.520 --> 00:05:48.519
+and probably easier to remember.
+
+00:05:48.520 --> 00:05:54.679
+Certainly easier than this freaking regular expression.
+
+00:05:54.680 --> 00:05:59.439
+I’ve got an even better improvement.
+
+00:05:59.440 --> 00:06:03.559
+The rx macro with regular expression snippets
+
+00:06:03.560 --> 00:06:05.759
+can be assigned to key words
+
+00:06:05.760 --> 00:06:08.679
+that I can then take advantage of.
+
+00:06:08.680 --> 00:06:13.479
+Now our command would be much simpler to type.
+
+NOTE 6. Loops are better with predicates
+
+00:06:13.480 --> 00:06:16.159
+6. Loops are better with predicates.
+
+00:06:16.160 --> 00:06:18.759
+Let’s say you want to remove the execute bit
+
+00:06:18.760 --> 00:06:20.479
+from files that have it.
+
+00:06:20.480 --> 00:06:24.399
+In a shell like bash, you need both a for loop and an if,
+
+00:06:24.400 --> 00:06:26.599
+as you can see in this example.
+
+00:06:26.600 --> 00:06:31.559
+With eshell, use a predicate to combine into a simple loop.
+
+00:06:31.560 --> 00:06:34.359
+The paren x after a file glob
+
+00:06:34.360 --> 00:06:36.879
+filters for only files marked as executable.
+
+00:06:36.880 --> 00:06:43.559
+Now here is another improvement.
+
+00:06:43.560 --> 00:06:47.959
+Since we often type loops to execute on one command,
+
+00:06:47.960 --> 00:06:49.519
+what about creating a function
+
+00:06:49.520 --> 00:06:50.999
+that can do this all in one go?
+
+00:06:51.000 --> 00:06:57.599
+This do function splits the arguments on that double colon,
+
+00:06:57.600 --> 00:07:00.079
+where the left side is a single statement to run,
+
+00:07:00.080 --> 00:07:02.599
+and the right side is a list of files.
+
+00:07:02.600 --> 00:07:05.839
+I have to append and flatten it
+
+00:07:05.840 --> 00:07:07.639
+in order for it to work.
+
+00:07:07.640 --> 00:07:09.399
+It loops through each file,
+
+00:07:09.400 --> 00:07:12.079
+creating an eshell command with the file appended.
+
+00:07:12.080 --> 00:07:15.759
+With this, I can remove the execute bit
+
+00:07:15.760 --> 00:07:20.759
+on all CSV files that have it.
+
+00:07:20.760 --> 00:07:24.319
+I see that my example wasn’t too good, as most commands
+
+00:07:24.320 --> 00:07:29.039
+like chmod accept multiple files, but you get the idea.
+
+00:07:29.040 --> 00:07:33.159
+In my final, larger form on my website,
+
+00:07:33.160 --> 00:07:35.279
+I don’t assume the command expression accepts
+
+00:07:35.280 --> 00:07:36.719
+a file as a final argument,
+
+00:07:36.720 --> 00:07:39.639
+as I can also replace underscores with the filename.
+
+NOTE 7. Output of last command
+
+00:07:39.640 --> 00:07:45.399
+7. Output of last command.
+
+00:07:45.400 --> 00:07:48.799
+Most shells have a special variable
+
+00:07:48.800 --> 00:07:52.839
+like $? for the exit code of the last command.
+
+00:07:52.840 --> 00:07:55.919
+While reading through the source code,
+
+00:07:55.920 --> 00:07:58.799
+I noticed that the $$ refers to
+
+00:07:58.800 --> 00:08:00.599
+the output of the last command.
+
+00:08:00.600 --> 00:08:05.799
+This seems pretty cool.
+
+00:08:05.800 --> 00:08:10.759
+However, Eshell returns true or nil
+
+00:08:10.760 --> 00:08:12.719
+when running external commands,
+
+00:08:12.720 --> 00:08:15.879
+so accessing the output from a call to ls
+
+00:08:15.880 --> 00:08:19.479
+doesn’t work as expected.
+
+00:08:19.480 --> 00:08:21.119
+But this is Emacs.
+
+00:08:21.120 --> 00:08:23.159
+We can fix that.
+
+00:08:23.160 --> 00:08:28.119
+After running any command, eshell sets these four variables.
+
+00:08:28.120 --> 00:08:33.519
+I can hook a function call after every Eshell command.
+
+00:08:33.520 --> 00:08:36.759
+Using buffer-substring,
+
+00:08:36.760 --> 00:08:39.279
+I store the output into a global variable,
+
+00:08:39.280 --> 00:08:43.599
+and extend Eshell’s special variables list.
+
+00:08:43.600 --> 00:08:46.519
+In my Emacs configuration,
+
+00:08:46.520 --> 00:08:48.479
+I turned this variable into a ring,
+
+00:08:48.480 --> 00:08:51.439
+so while $$ works,
+
+00:08:51.440 --> 00:08:54.399
+so does array sub-scripting on that variable.
+
+00:08:54.400 --> 00:08:58.399
+This allows me to run a command
+
+00:08:58.400 --> 00:09:02.279
+and use the output from that command more than once.
+
+00:09:02.280 --> 00:09:05.279
+The code for this is a bit longer,
+
+00:09:05.280 --> 00:09:08.519
+so you’ll need to see my Emacs configuration for details.
+
+NOTE 8. Redirection back to Emacs
+
+00:09:08.520 --> 00:09:13.439
+8. Redirection back to Emacs.
+
+00:09:13.440 --> 00:09:14.879
+Output of any command
+
+00:09:14.880 --> 00:09:18.519
+can go to kill-ring (or the clipboard).
+
+00:09:18.520 --> 00:09:21.079
+Think of the implications.
+
+00:09:21.080 --> 00:09:23.839
+You don’t have to go into text selection mode.
+
+00:09:23.840 --> 00:09:26.239
+Just grab the output.
+
+00:09:26.240 --> 00:09:30.279
+In fact, with our $$ improvement,
+
+00:09:30.280 --> 00:09:33.239
+we can always copy the output from the last command
+
+00:09:33.240 --> 00:09:34.079
+to the clipboard.
+
+00:09:34.080 --> 00:09:37.999
+Better yet, let’s write the output
+
+00:09:38.000 --> 00:09:39.399
+to our engineering notebook.
+
+00:09:39.400 --> 00:09:41.679
+Here’s my idea.
+
+00:09:41.680 --> 00:09:46.079
+First, create a capture template that takes a string,
+
+00:09:46.080 --> 00:09:48.199
+or if called interactively, the region,
+
+00:09:48.200 --> 00:09:51.879
+and that does an immediate-finish after inserting
+
+00:09:51.880 --> 00:09:53.879
+that string to the default notes file.
+
+00:09:53.880 --> 00:09:57.679
+Next, create a wrapper function
+
+00:09:57.680 --> 00:10:01.559
+to call org-capture-string to run that template.
+
+00:10:01.560 --> 00:10:07.639
+Finally, we add our new function to eshell-virtual-targets.
+
+00:10:07.640 --> 00:10:08.759
+Let’s see this in action.
+
+00:10:08.760 --> 00:10:15.707
+I have a CSV file of user information.
+
+00:10:15.708 --> 00:10:19.719
+I can use grep and cut to extract some of that
+
+00:10:19.720 --> 00:10:26.879
+and write it out to this month’s engineering notebook.
+
+NOTE 9. Using Emacs buffers
+
+00:10:26.880 --> 00:10:35.279
+9. Using Emacs buffers.
+
+00:10:35.280 --> 00:10:39.159
+Why leave the results of eshell commands
+
+00:10:39.160 --> 00:10:40.279
+in the *eshell* buffer?
+
+00:10:40.280 --> 00:10:44.119
+Send the output into a buffer where you can use it.
+
+00:10:44.120 --> 00:10:47.999
+Here’s a call to ripgrep
+
+00:10:48.000 --> 00:10:50.759
+that searches for lines with email addresses
+
+00:10:50.760 --> 00:10:53.519
+using a complicated regular expression
+
+00:10:53.520 --> 00:10:56.079
+that I added to my prx macro.
+
+00:10:56.080 --> 00:11:01.079
+When I switch to this almost-grep buffer,
+
+00:11:01.080 --> 00:11:03.319
+I can turn on grep-mode.
+
+00:11:03.320 --> 00:11:09.039
+Now I can jump around as if I just called grep directly.
+
+00:11:09.040 --> 00:11:14.759
+Perhaps I’m proficient with my prx macro
+
+00:11:14.760 --> 00:11:16.639
+to filter out entries,
+
+00:11:16.640 --> 00:11:19.279
+but not good with shell commands
+
+00:11:19.280 --> 00:11:23.999
+that I can use in pipes to extract just one…
+
+00:11:24.000 --> 00:11:26.039
+the address column, for instance?
+
+00:11:26.040 --> 00:11:28.959
+Let’s just extract it,
+
+00:11:28.960 --> 00:11:33.279
+send it to a buffer called email-list,
+
+00:11:33.280 --> 00:11:38.479
+and now I can use Emacs commands that I know and love
+
+00:11:38.480 --> 00:11:39.799
+to edit the data directly.
+
+00:11:39.800 --> 00:11:55.799
+We currently have an over-sight
+
+00:11:55.800 --> 00:11:58.839
+that the Eshell’s built-in cat command
+
+00:11:58.840 --> 00:12:02.719
+doesn’t pipe buffer contents as standard in.
+
+00:12:02.720 --> 00:12:07.919
+So I created a bcat, a buffer cat, function to do this.
+
+00:12:07.920 --> 00:12:09.879
+So this command works
+
+00:12:09.880 --> 00:12:14.599
+to grab my email addresses I just extracted
+
+00:12:14.600 --> 00:12:16.319
+and send them to another program.
+
+00:12:16.320 --> 00:12:20.959
+If you’re interested, I have a more elaborate
+
+00:12:20.960 --> 00:12:25.759
+and yet simpler workflow surrounding sending data
+
+00:12:25.760 --> 00:12:28.399
+back and forth from Eshell to Emacs buffers.
+
+NOTE 10. cd to remote systems
+
+00:12:28.400 --> 00:12:35.679
+10. Did I mention that you can cd to remote systems?
+
+00:12:35.680 --> 00:12:39.879
+This command uses SSH to jump to my host, goblin,
+
+00:12:39.880 --> 00:12:44.039
+start a root session, and jump to the etc directory.
+
+00:12:44.040 --> 00:12:47.719
+Remember that Tramp can be finicky
+
+00:12:47.720 --> 00:12:52.839
+if you start blinging your remote hosts with oh-my-zshell,
+
+00:12:52.840 --> 00:12:57.790
+and funky prompts and things like that,
+
+00:12:57.791 --> 00:12:59.359
+so your mileage may vary.
+
+NOTE Summary
+
+00:12:59.360 --> 00:13:03.959
+In summary: Use eshell if you want
+
+00:13:03.960 --> 00:13:07.319
+a quick way to run commands and Emacs functions as a REPL,
+
+00:13:07.320 --> 00:13:11.479
+or to run an OS program but process the output with Emacs.
+
+00:13:11.480 --> 00:13:15.919
+Keep in mind that Eshell has two types of subshells,
+
+00:13:15.920 --> 00:13:19.599
+and you can mix and match during a command call.
+
+00:13:19.600 --> 00:13:22.639
+The rx macro is really cool.
+
+00:13:22.640 --> 00:13:26.599
+Eshell loops are better with filters and predicates …
+
+00:13:26.600 --> 00:13:28.239
+if you can remember them.
+
+00:13:28.240 --> 00:13:30.959
+Take advantage of Emacs buffers
+
+00:13:30.960 --> 00:13:32.879
+to really enhance your shell experience.
+
+00:13:32.880 --> 00:13:36.039
+You’ve now seen that just like Emacs,
+
+00:13:36.040 --> 00:13:39.519
+I’ve crafted Eshell to be my own shell creation,
+
+00:13:39.520 --> 00:13:41.039
+tailored to my workflow.
+
+00:13:41.040 --> 00:13:44.799
+So, steal my spells, cast your own magic,
+
+00:13:44.800 --> 00:13:48.759
+but feel free to share your incantations back to me.
+
+00:13:48.760 --> 00:13:51.359
+I’ve gone over my time allotment, so we’ll have to
+
+00:13:51.360 --> 00:13:53.679
+continue this discussion on the intertubes.
+
+00:13:53.680 --> 00:13:57.159
+Why yes, I have joined the birdless diaspora,
+
+00:13:57.160 --> 00:13:59.199
+so toot me over there.
+
+00:13:59.200 --> 00:14:01.920
+Thanks.