WEBVTT captioned by mark NOTE Introduction 00:00:02.940 --> 00:00:08.719 Welcome to Emacs as a Shell, a talk by Christopher Howard for 00:00:08.720 --> 00:00:13.799 Emacs Conference 2024. 00:00:13.800 --> 00:00:18.399 In this talk, I would like to explore, or advocate for, a 00:00:18.400 --> 00:00:21.919 particular perspective. I want to encourage people to 00:00:21.920 --> 00:00:26.479 think of Emacs not as simply an editor or a development 00:00:26.480 --> 00:00:31.119 environment, but rather as a shell, or at least something 00:00:31.120 --> 00:00:33.919 that allows us to do most of the things that we might 00:00:33.920 --> 00:00:37.880 otherwise want to do from a shell. NOTE What do I mean by shell? 00:00:37.881 --> 00:00:40.839 What do I mean by shell? By 00:00:40.840 --> 00:00:45.439 shell, I mean basically an interface that allows us to 00:00:45.440 --> 00:00:50.679 interact with the rest of our system by entering commands. 00:00:50.680 --> 00:00:55.039 That definition is, perhaps, a little too broad, and so I 00:00:55.040 --> 00:00:58.439 will try to narrow it down with a list of features that, 00:00:58.440 --> 00:01:03.279 historically, we have come to expect from a shell. The Bash 00:01:03.280 --> 00:01:07.719 shell is one very portable and well-known shell, and for 00:01:07.720 --> 00:01:13.599 many of us it is maybe the prototypical example. But in the 00:01:13.600 --> 00:01:16.879 past there have been many other shells, and there are other 00:01:16.880 --> 00:01:21.119 shells available today. If we are willing to be flexible in 00:01:21.120 --> 00:01:25.559 our thinking, we can think of Emacs as being a shell, or at 00:01:25.560 --> 00:01:28.879 least providing most of the functionality that we expect 00:01:28.880 --> 00:01:38.559 from a shell. NOTE What I do not mean 00:01:38.560 --> 00:01:42.759 Before further expanding on this idea, I must emphasize 00:01:42.760 --> 00:01:47.159 what I do not mean. First of all, I am not talking about 00:01:47.160 --> 00:01:51.439 running Bash, or some other external shell, from within 00:01:51.440 --> 00:01:56.439 Emacs, although this is certainly possible. I am arguing, 00:01:56.440 --> 00:02:02.439 rather, for using Emacs as a shell, instead of other shells. 00:02:02.440 --> 00:02:06.239 Second, I do not mean running a terminal emulator from 00:02:06.240 --> 00:02:11.399 within Emacs. Emacs has a built-in terminal emulator, but 00:02:11.400 --> 00:02:15.839 this is not what I mean. A terminal emulator is essentially a 00:02:15.840 --> 00:02:20.039 program designed to control the cursor and text appearance 00:02:20.040 --> 00:02:23.999 in response to various control codes in order to mimic a 00:02:24.000 --> 00:02:28.439 terminal display device. There are certainly legitimate 00:02:28.440 --> 00:02:32.559 reasons to do this. Nevertheless, in general, it does not 00:02:32.560 --> 00:02:36.519 make much sense to run a terminal emulator within Emacs, 00:02:36.520 --> 00:02:39.719 because Emacs has its own commands for controlling the 00:02:39.720 --> 00:02:45.039 cursor and text appearance. Also, due to the way Emacs was 00:02:45.040 --> 00:02:48.919 designed historically, Emacs itself believes that it is 00:02:48.920 --> 00:02:53.119 running on a terminal. So you end up with layers upon layers 00:02:53.120 --> 00:02:58.199 of terminal emulation. Anyhow, at the end of the day, Emacs 00:02:58.200 --> 00:03:01.839 will not perform as well as a dedicated terminal emulator 00:03:01.840 --> 00:03:08.079 program. I also think that, as we try to force ANSI terminal 00:03:08.080 --> 00:03:12.359 emulation into our Emacs workflow, this ultimately will be 00:03:12.360 --> 00:03:15.879 a hindrance to us in taking advantage of the natural and 00:03:15.880 --> 00:03:19.319 pleasant interfaces that are already available to us 00:03:19.320 --> 00:03:24.999 within Emacs. In brief, if your goal is simply to figure out 00:03:25.000 --> 00:03:28.499 how to be able to do all your normal Bash command line 00:03:28.500 --> 00:03:32.359 wizardry from within an Emacs window instead of a GNOME 00:03:32.360 --> 00:03:36.479 console window, you are headed down a different set of train 00:03:36.480 --> 00:03:43.199 tracks than I am. Also, something which I fear may confuse 00:03:43.200 --> 00:03:47.919 the issue for some viewers is the fact that Emacs ships with 00:03:47.920 --> 00:03:52.839 its own unique built-in shell, called the Emacs shell, or 00:03:52.840 --> 00:03:59.079 Eshell. 00:03:59.080 --> 00:04:02.959 Eshell aims to be a legitimate shell, and provides a very 00:04:02.960 --> 00:04:07.599 similar experience to other shells like Bash, while being 00:04:07.600 --> 00:04:11.119 well integrated into the Emacs interface, and without 00:04:11.120 --> 00:04:15.639 giving up the power of the Emacs Lisp engine. Eshell will be 00:04:15.640 --> 00:04:19.139 mentioned multiple times in this talk. The entire talk 00:04:19.140 --> 00:04:24.179 could, in fact, be about Eshell, except that I want the talk 00:04:24.180 --> 00:04:28.319 to cover all aspects of Emacs shell-like functionality 00:04:28.320 --> 00:04:32.079 through its other tools, such as interactive commands and 00:04:32.080 --> 00:04:37.079 special modes. So, hopefully we can keep distinct in our 00:04:37.080 --> 00:04:43.279 mind the ideas of Emacs as a shell versus the Emacs shell, 00:04:43.880 --> 00:04:50.159 though the latter is an important part of the former. NOTE What is a shell? 00:04:50.160 --> 00:04:55.399 Let's get back to the fundamental idea of what is a shell. In 00:04:55.400 --> 00:04:59.159 the broadest definition, a shell is an interface which 00:04:59.160 --> 00:05:02.279 allows you to interact with your operating system through 00:05:02.280 --> 00:05:06.840 commands. However, from a historical perspective, there 00:05:06.841 --> 00:05:10.699 are a few basic capabilities which we expect to be part of 00:05:10.700 --> 00:05:17.880 every shell. 00:05:17.881 --> 00:05:21.420 First of all, the shell provides a means of launching 00:05:21.421 --> 00:05:26.440 external programs. Some internal or built-in commands 00:05:26.441 --> 00:05:31.679 might also be made available. Second, the shell provides a 00:05:31.680 --> 00:05:36.820 means of managing environment variables. In the past, 00:05:36.821 --> 00:05:40.580 environment variables often played a critical role as a 00:05:40.581 --> 00:05:45.360 means of passing in options, file names, device names, and 00:05:45.361 --> 00:05:50.119 suchlike to external programs. This is not quite as common 00:05:50.120 --> 00:05:54.080 today, but the environment still plays a critical role in 00:05:54.081 --> 00:05:57.619 managing things such as the path to executables and 00:05:57.620 --> 00:06:03.080 libraries, as well as various other user, desktop, and 00:06:03.081 --> 00:06:08.280 system settings. The shell modifies the environment and 00:06:08.281 --> 00:06:11.620 passes it on to external programs. 00:06:13.540 --> 00:06:17.580 Historically, job control was expected to be either a 00:06:17.581 --> 00:06:21.560 function of the shell, or easily accessible from it. 00:06:21.561 --> 00:06:24.019 Usually today, our personal computing is not 00:06:24.020 --> 00:06:29.280 batch-oriented. But typically, shells can run multiple 00:06:29.281 --> 00:06:34.599 processes simultaneously, as well as provide means to 00:06:34.600 --> 00:06:38.780 suspend and terminate processes, which are useful 00:06:38.781 --> 00:06:44.880 features. Shells should be able to redirect and pipeline 00:06:44.881 --> 00:06:49.100 process input and output. This allows the user to connect 00:06:49.101 --> 00:06:53.880 process input and output with files, devices, or other 00:06:53.881 --> 00:06:58.813 processes. Finally, shells are expected to have some 00:06:58.814 --> 00:07:02.380 limited scripting capability, such as the 00:07:02.381 --> 00:07:06.613 POSIX-compliant set of program statements and 00:07:06.614 --> 00:07:08.880 conditionals that Bash provides. 00:07:11.100 --> 00:07:15.113 As command-line wizards, there are a number of tasks we 00:07:15.114 --> 00:07:18.280 expect to be able to do quickly and easily from our shell, 00:07:18.660 --> 00:07:21.646 even though these tasks are not the domain of the shell 00:07:21.647 --> 00:07:27.880 itself. A common task is file management and navigation. We 00:07:27.881 --> 00:07:31.113 quickly navigate and manipulate the file system with 00:07:31.114 --> 00:07:34.813 standard utilities that do things like change the current 00:07:34.814 --> 00:07:39.380 working directory, rename files, move files, and delete 00:07:39.381 --> 00:07:44.146 files. We usually expect to have access to some additional 00:07:44.147 --> 00:07:48.380 process management utilities. These allow us to do things 00:07:48.381 --> 00:07:51.780 such as find out the status of all processes running on the 00:07:51.781 --> 00:07:57.980 system, and send signals to processes. Finally, we expect 00:07:57.981 --> 00:08:02.113 to have access to some basic networking utilities. For 00:08:02.114 --> 00:08:05.413 example, we should be able to run commands that set up 00:08:05.414 --> 00:08:09.513 network interfaces, ping computers, and download files. 00:08:09.514 --> 00:08:16.080 With a little reflection, we can see that Emacs can provide 00:08:16.081 --> 00:08:20.146 all or nearly all of the functionality we have described so 00:08:20.147 --> 00:08:24.046 far. And the functionality can be called conveniently 00:08:24.047 --> 00:08:26.746 through one of several methods. 00:08:33.520 --> 00:08:43.846 Either a normal interactive call, like M-x something, or a 00:08:43.847 --> 00:08:46.013 call to an elisp function, 00:08:53.620 --> 00:09:01.180 or through Eshell commands, or through some special buffer 00:09:01.181 --> 00:09:06.946 mode, such as the directory editor, which provides its own 00:09:06.947 --> 00:09:09.413 interface to some functionality. 00:09:09.414 --> 00:09:17.413 It may be going too far to say that Emacs is a full replacement 00:09:17.414 --> 00:09:21.713 for shells like Bash. Nevertheless, we can see that Emacs 00:09:21.714 --> 00:09:25.680 can do most of the things that we might otherwise do with our 00:09:25.681 --> 00:09:26.911 shell. NOTE Launching external processes 00:09:26.912 --> 00:09:32.513 Let us give some examples. First, can Emacs launch 00:09:32.514 --> 00:09:36.680 external commands? Of course. Now, there are something 00:09:36.681 --> 00:09:40.446 like a half-dozen different ways to do that within Emacs, and 00:09:40.447 --> 00:09:46.713 some are more convenient than others. From any Elisp 00:09:46.714 --> 00:09:50.780 program, we can call functions like make-process and 00:09:50.781 --> 00:09:53.913 call-process to launch external processes. 00:10:12.460 --> 00:10:16.846 These, however, generally are not convenient for quick, 00:10:16.847 --> 00:10:22.380 one-off commands. Another option would be to run Eshell, 00:10:22.381 --> 00:10:26.580 which would allow us to call the external program from a 00:10:26.581 --> 00:10:28.946 familiar command line prompt. 00:10:34.160 --> 00:10:38.880 If we do not actually want to drop into Eshell just to run one 00:10:38.881 --> 00:10:42.213 command, we also have the interactive command, 00:10:42.214 --> 00:10:44.613 eshell-command, 00:10:52.420 --> 00:10:56.746 which would allow us to call the external program from a 00:10:56.747 --> 00:10:59.180 familiar command line prompt. 00:11:09.940 --> 00:11:12.080 If we do not actually want to drop an 00:11:12.081 --> 00:11:15.699 Eshell just to run one command, as I just mentioned, we also 00:11:15.700 --> 00:11:19.799 have the interactive command eshell-command, which allows 00:11:19.800 --> 00:11:23.399 us to enter in a one-off command and run that immediately. 00:11:25.420 --> 00:11:28.799 And finally, there is also an interactive command called 00:11:28.800 --> 00:11:30.499 simply shell-command. 00:11:34.600 --> 00:11:39.099 Shell command is like Eshell command, but instead passes 00:11:39.100 --> 00:11:42.899 the command off to our system shell, for example, bash. 00:11:43.940 --> 00:11:48.599 This is cheating, of course, but it might be useful or convenient 00:11:48.600 --> 00:11:57.299 in some scenarios. NOTE Environment variables 00:11:57.300 --> 00:12:01.899 Regarding environment variables, Emacs can read and 00:12:01.900 --> 00:12:05.399 manipulate the environment variables, which in turn get 00:12:05.400 --> 00:12:09.659 passed on to processes which it launches. The 00:12:09.660 --> 00:12:12.899 general-purpose interactive commands for this are 00:12:12.900 --> 00:12:18.499 getenv and setenv. These commands 00:12:18.500 --> 00:12:21.799 deal with the one environment that is available throughout 00:12:21.800 --> 00:12:25.699 all parts of your running Emacs session. In other words, 00:12:25.700 --> 00:12:28.999 these functions deal with a global environment, which is 00:12:29.000 --> 00:12:32.099 the same wherever you are running getenv or 00:12:32.100 --> 00:12:34.399 setenv. 00:13:00.340 --> 00:13:04.259 An important exception is that every instance of Eshell 00:13:04.260 --> 00:13:07.599 maintains a distinct environment that will not be affected 00:13:07.600 --> 00:13:13.980 by setenv calls run in other buffers. Also, Eshell 00:13:13.981 --> 00:13:16.446 has some additional syntax for dealing with its 00:13:16.447 --> 00:13:20.780 environment, including the set and export syntax. 00:13:38.647 --> 00:13:47.113 Regarding job control and process management, Emacs does 00:13:47.114 --> 00:13:50.880 not provide job control in the way that Bash users are used 00:13:50.881 --> 00:13:57.080 to. We can, however, launch asynchronous processes, and do 00:13:57.081 --> 00:14:01.580 various things to them. From Eshell, or an eshell-command 00:14:01.581 --> 00:14:07.180 call, we can append the ampersand symbol to the command, and 00:14:07.181 --> 00:14:11.013 this will cause the process to run asynchronously in a 00:14:11.014 --> 00:14:13.313 dedicated buffer. 00:14:20.881 --> 00:14:25.280 Now, if the command is launched from Eshell, it will not 00:14:25.281 --> 00:14:31.180 actually run in a separate buffer, but the output will go to 00:14:31.181 --> 00:14:33.413 the Eshell buffer. NOTE Processes 00:14:54.400 --> 00:14:59.580 We can run the interactive command list-processes to see 00:14:59.581 --> 00:15:02.846 all the processes running for our current Emacs session. 00:15:11.747 --> 00:15:17.646 In Eshell, we can run the command "jobs" to get the same list. 00:15:17.647 --> 00:15:22.813 This will show the process name, process buffer name, 00:15:22.814 --> 00:15:28.613 process ID, and some other information. We can select the 00:15:28.614 --> 00:15:32.880 process buffer in the process list to bring up that process 00:15:32.881 --> 00:15:36.213 buffer. 00:15:42.414 --> 00:15:47.046 We can also use the interactive command signal-process to 00:15:47.047 --> 00:15:52.980 send any signal to a process, including "stop" to suspend the 00:15:52.981 --> 00:15:58.380 process, "continue" to resume the process, and "interrupt" or 00:15:58.381 --> 00:16:02.546 kill to terminate the process. NOTE Redirecting and pipelining input and output 00:17:00.180 --> 00:17:04.813 Regarding redirecting and pipelining input and output, 00:17:04.814 --> 00:17:11.613 Eshell does support redirection similar to Bash, so you can 00:17:11.614 --> 00:17:17.046 overwrite and append to files and some other objects. Input 00:17:17.047 --> 00:17:22.380 redirection is not yet implemented, but it is on the Eshell 00:17:22.381 --> 00:17:29.213 to-do list. Eshell also has pipes. The default pipe, which 00:17:29.214 --> 00:17:33.220 uses the familiar vertical bar symbol, pipes the data 00:17:33.221 --> 00:17:36.980 between the commands using an intermediate Emacs buffer. 00:17:36.981 --> 00:17:41.200 This, while usually quite practical, is less efficient 00:17:41.201 --> 00:17:46.319 than the system pipe. Therefore, Eshell also makes 00:17:46.320 --> 00:17:50.146 available a star-modified version, which uses the system 00:17:50.147 --> 00:17:52.546 pipe through a call to your system shell. 00:17:56.881 --> 00:17:59.413 So we can do things like 00:18:02.340 --> 00:18:05.860 direct output to a file. 00:18:15.100 --> 00:18:20.240 We're unfortunately not able to do input redirection, but 00:18:20.241 --> 00:18:22.540 we can use pipes. 00:18:41.760 --> 00:18:45.639 Elisp can manipulate and tie together processes in various 00:18:45.640 --> 00:18:50.999 ways, such as process filters and pipe processes, but I 00:18:51.000 --> 00:18:56.559 won't attempt to cover that. I feel like you should mention 00:18:56.560 --> 00:19:02.119 again that we have two kinds of pipes here available. So this 00:19:02.120 --> 00:19:09.239 pipe, the standard one, will pipe the data through Emacs 00:19:09.240 --> 00:19:16.759 buffers. That's very practical in most cases, but it is less 00:19:16.760 --> 00:19:22.919 efficient than piping through the system pipe. So Eshell 00:19:22.920 --> 00:19:28.119 makes available another symbol for that, star, vertical 00:19:28.120 --> 00:19:38.339 bar, that allows you to explicitly use the system pipe. 00:19:38.340 --> 00:19:43.599 Regarding scripting: Of course, using Emacs makes 00:19:43.600 --> 00:19:47.959 available all the power of the Elisp API and third-party 00:19:47.960 --> 00:19:54.719 packages, so we have that out of the gate. Eshell also has 00:19:54.720 --> 00:19:59.639 control flow statements, like an "if" construct and a "for" 00:19:59.640 --> 00:20:06.519 construct. See the Eshell info manual, section 3.7, for 00:20:06.520 --> 00:20:07.719 more details. NOTE Scripts 00:20:09.440 --> 00:20:13.839 And if you wish to write a script entirely in Eshell syntax, 00:20:13.840 --> 00:20:18.559 and store it in a separate file, this is possible with recent 00:20:18.560 --> 00:20:20.159 versions of Emacs. 00:20:31.840 --> 00:20:34.679 Here's an example of a brief script that I wrote. 00:20:37.560 --> 00:20:42.679 Unfortunately, an eshell mode for proper syntax 00:20:42.680 --> 00:20:46.279 highlighting is not yet available, but hopefully that will 00:20:46.280 --> 00:20:51.279 be forthcoming. Note that Eshell syntax allows elisp 00:20:51.280 --> 00:20:55.079 forms to be interspersed with regular command form for 00:20:55.080 --> 00:20:58.759 additional scripting power. We will discuss this a little 00:20:58.760 --> 00:21:01.999 more later. NOTE File system management 00:21:11.780 --> 00:21:16.759 Regarding file system management. In Emacs, many of the 00:21:16.760 --> 00:21:20.239 common file system operations are available as 00:21:20.240 --> 00:21:26.759 interactive commands. For example, M-x cd, to change your 00:21:26.760 --> 00:21:32.839 buffer's current working directory, and other M-x commands 00:21:32.840 --> 00:21:37.439 such as make-directory 00:21:40.780 --> 00:21:42.679 chmod, 00:21:43.260 --> 00:21:51.159 and delete-file. Of course, you can also drop into Eshell, 00:21:53.840 --> 00:22:00.639 or use M-x eshell-command to run the usual external commands 00:22:00.640 --> 00:22:07.039 for file system manipulation. Also, a file manager is built 00:22:07.040 --> 00:22:14.279 into Emacs, which can be run by calling M-x dired. 00:22:19.640 --> 00:22:24.559 The directory editor is powerful, but it is a bit strange to 00:22:24.560 --> 00:22:28.679 folks expecting something like Midnight Commander or the 00:22:28.680 --> 00:22:35.639 GNOME file manager. It gives us a number of helpful features 00:22:35.640 --> 00:22:43.639 like the ability to mark files, and to run elisp functions on 00:22:44.700 --> 00:22:48.439 them, and some other interesting ways to manipulate and 00:22:48.440 --> 00:22:54.079 rename the files. However, third-party Emacs extensions 00:22:54.080 --> 00:22:58.479 such as Midnight Commander Mode and Sunrise Commander are 00:22:58.480 --> 00:23:03.879 available to provide a Midnight Commander experience, for those who 00:23:03.880 --> 00:23:10.319 prefer that sort of file management. 00:23:10.320 --> 00:23:14.879 Emacs also has the nifty TRAMP functionality built in, 00:23:14.880 --> 00:23:19.159 which allows you, most of the time, to easily edit files on 00:23:19.160 --> 00:23:22.719 other computers, as well as manipulate the file system. 00:23:23.180 --> 00:23:27.839 This transparently works through SSH and some other 00:23:27.840 --> 00:23:30.079 protocols that you can specify. NOTE Networking 00:23:43.560 --> 00:23:48.159 Regarding networking features, I don't have a lot of 00:23:48.160 --> 00:23:51.639 interesting things to say about this at the present, so I'll 00:23:51.640 --> 00:23:54.919 skip through this quickly. But if you do a little research, 00:23:54.920 --> 00:23:58.799 you will see that Emacs has a lot of functionality relating 00:23:58.800 --> 00:24:02.359 to making network connections, interacting with the web, 00:24:02.780 --> 00:24:07.859 and such like, both built-in and in available packages, as 00:24:07.860 --> 00:24:14.399 well as modes for doing things like Web browsing and Gemini 00:24:14.400 --> 00:24:20.599 browsing. And of course, you can run the usual standard 00:24:20.600 --> 00:24:23.639 networking commands for your system through Eshell. NOTE A brief tour of Eshell 00:24:30.120 --> 00:24:33.759 So having put forward the main arguments for this talk, I 00:24:33.760 --> 00:24:38.199 would like to take some time now to give a brief tour of a few of 00:24:38.200 --> 00:24:43.799 the features of Eshell, the Emacs shell. It bears 00:24:43.800 --> 00:24:46.999 emphasizing that Eshell is not a drop-in replacement for 00:24:47.000 --> 00:24:51.879 Bash, or even a Bash clone, though I believe the developers 00:24:51.880 --> 00:24:56.839 are trying to make much of the syntax very similar. Also, 00:24:56.840 --> 00:25:00.479 Eshell is not a terminal emulator, and it will not display 00:25:00.480 --> 00:25:04.679 correctly applications which use advanced ANSI control 00:25:04.680 --> 00:25:10.119 codes. However, Eshell can be configured to be aware of such 00:25:10.120 --> 00:25:13.300 applications, and to run them automatically within the 00:25:13.301 --> 00:25:19.940 Emacs terminal emulator when launched. See section 5.1 of 00:25:19.941 --> 00:25:24.100 the Eshell manual titled Visual Commands. 00:25:32.540 --> 00:25:36.759 Though Eshell is not Bash, it has multiple features, 00:25:36.760 --> 00:25:40.679 pertaining mainly to its by-design Emacs integration, 00:25:40.680 --> 00:25:44.639 which may make it more appealing to use than Bash or another 00:25:44.640 --> 00:25:45.359 shell. 00:25:48.160 --> 00:25:52.039 For one, Eshell allows entering commands on the command 00:25:52.040 --> 00:25:55.960 line that are space and new line separated, without 00:25:55.961 --> 00:26:01.280 parentheses. Of course, all the other shells do this. But 00:26:01.281 --> 00:26:06.280 within Eshell, it is possible to enter internal Emacs 00:26:06.281 --> 00:26:11.060 functions, as well as external commands. 00:26:13.240 --> 00:26:45.739 This allows us to do things like this. 00:26:45.740 --> 00:26:49.759 As far as I understand, it is possible to enter any Emacs 00:26:49.760 --> 00:26:53.959 function on the Eshell command line. However, some special 00:26:53.960 --> 00:26:58.399 syntax may be required if you are trying to pass in something 00:26:58.400 --> 00:27:00.799 that is not a string or a number. 00:27:04.380 --> 00:27:07.919 As you might have noticed in the last example, Eshell makes 00:27:07.920 --> 00:27:12.919 it possible to use an Emacs buffer as a sink for output. It 00:27:12.920 --> 00:27:18.039 also allows using a buffer as a source of input, though this 00:27:18.040 --> 00:27:21.839 is slightly more complicated, since the buffer must be 00:27:21.840 --> 00:27:27.199 converted to a string first. I have distilled this down into 00:27:27.200 --> 00:27:30.279 my own function, named with the "at" symbol. 00:27:36.640 --> 00:27:40.319 And I will provide the brief snippet of code for this later. 00:27:54.640 --> 00:28:02.499 So to give an example, here's our messages buffer. 00:28:02.500 --> 00:28:05.399 And from Eshell, we can do something like this. 00:28:29.780 --> 00:28:34.439 Let's say here we wanted to grab our messages buffer to see 00:28:34.440 --> 00:28:38.079 everything that we had been loading during the startup 00:28:38.080 --> 00:28:38.959 process. 00:28:48.060 --> 00:28:51.879 So you can see how that could be very handy in a number of 00:28:51.880 --> 00:28:52.959 scenarios. 00:28:55.060 --> 00:29:00.239 I wanted to briefly mention that we have a helpful function 00:29:00.240 --> 00:29:03.439 here called eshell-insert-buffer-name, 00:29:11.120 --> 00:29:15.359 which allows us to insert a buffer name into the current 00:29:15.360 --> 00:29:18.439 buffer at point using completion, 00:29:24.680 --> 00:29:32.879 which can save you a lot of typing. 00:29:32.880 --> 00:29:34.799 Another nice feature of Eshell 00:29:37.220 --> 00:29:41.199 is that it allows integrating ELisp into the command line 00:29:41.200 --> 00:29:48.879 call. Let's give another example. Say we wanted to echo the 00:29:48.880 --> 00:29:53.919 date to an event file or an event log. 00:29:56.720 --> 00:30:01.639 I should probably take a moment to explain this asterisk 00:30:01.640 --> 00:30:06.999 that I'm occasionally using. So since Emacs, or excuse me, 00:30:07.000 --> 00:30:11.719 since Eshell can use internal or external Emacs, excuse me, 00:30:11.720 --> 00:30:16.999 internal Emacs commands or external commands, it may 00:30:17.000 --> 00:30:21.679 sometimes be necessary to clarify which one you want to use, 00:30:22.380 --> 00:30:27.079 since the names may overlap. Since my Eshell is configured 00:30:27.080 --> 00:30:32.319 by default to prefer the internal Emacs functions, then 00:30:32.320 --> 00:30:37.799 sometimes I have to use the asterisk to specify that I want 00:30:37.800 --> 00:30:39.079 the external version. 00:30:42.680 --> 00:31:02.639 Here I can insert a bit of Elisp, 00:31:03.180 --> 00:31:06.119 and then redirect the output to the event log. 00:31:18.720 --> 00:31:22.639 Last, I want to mention that there are some optional Eshell 00:31:22.640 --> 00:31:27.159 modules in Emacs, not turned on by default, which provide 00:31:27.160 --> 00:31:29.039 additional nifty features. 00:31:40.540 --> 00:31:45.639 On my system, I have most of the optional modules turned on. 00:31:58.320 --> 00:32:03.199 An interesting module is eshell-smart, which does various 00:32:03.200 --> 00:32:07.319 things with cursor positioning and scrolling, so as to make 00:32:07.320 --> 00:32:10.399 editing commands and reviewing output easier. 00:32:18.340 --> 00:32:23.619 Let's say I was to change directory to my boot directory 00:32:30.880 --> 00:32:35.039 and use a command which involves lots of output. 00:32:39.900 --> 00:32:44.359 You'll notice right away that the cursor positioning is set 00:32:44.360 --> 00:32:48.719 such that I'm immediately able to view the top of the output. 00:32:48.720 --> 00:32:52.879 Also, I'm able to use the space bar to page through the 00:32:52.880 --> 00:32:56.079 output. 00:32:56.080 --> 00:33:01.919 So this is an opinionated feature, which assumes that 00:33:01.920 --> 00:33:05.399 you're likely going to want to review the output 00:33:05.400 --> 00:33:10.559 immediately, or that you often will. Of course, you can 00:33:10.560 --> 00:33:17.599 always jump to the end. 00:33:19.980 --> 00:33:23.919 Also, after a command is entered, the cursor is immediately 00:33:23.920 --> 00:33:28.279 repositioned to make it easy to edit the command. 00:33:53.020 --> 00:33:56.519 And also, if I don't want to edit the command, and I do not want 00:33:56.520 --> 00:33:59.679 to review the output, I can simply start typing another 00:33:59.680 --> 00:34:00.359 command. 00:34:11.260 --> 00:34:15.519 So that covers the brief tour of Eshell features. 00:34:17.760 --> 00:34:21.127 And that basically ends my talk. NOTE Login shell 00:34:21.128 --> 00:34:22.380 However, a handful of 00:34:22.381 --> 00:34:28.719 viewers might be wondering, is it possible to set Emacs to be 00:34:28.720 --> 00:34:37.639 my login shell to completely replace bash in your login 00:34:37.640 --> 00:34:43.719 experience? The answer is yes, but in practice there are 00:34:43.720 --> 00:34:47.399 various difficulties involved which might make it not 00:34:47.400 --> 00:34:48.359 worth the trouble. 00:35:00.440 --> 00:35:03.479 Before doing this, you'll have to answer a few initial 00:35:03.480 --> 00:35:09.519 questions. Do you want to make a new Emacs instance every 00:35:09.520 --> 00:35:13.759 time you log in, or do you want it to connect to an Emacs 00:35:13.760 --> 00:35:20.599 server? Which is popular among Emacs users, to reuse the 00:35:20.600 --> 00:35:26.599 session, or to connect to the existing session. Also, do you 00:35:26.600 --> 00:35:30.639 want a different result, whether in graphical or a terminal 00:35:30.640 --> 00:35:34.679 environment? And are you okay with your initialization 00:35:34.680 --> 00:35:39.559 file being run every time you log in, including every new tab 00:35:39.560 --> 00:35:44.520 you open in a terminal emulator? If we assume that you are 00:35:44.521 --> 00:35:50.339 using a system with /etc/passwd user management, you get 00:35:50.340 --> 00:35:53.999 one field to specify the name of the shell program that you 00:35:54.000 --> 00:35:58.479 want to use, and no arguments are allowed. So maybe you can 00:35:58.480 --> 00:36:02.679 see how this might be challenging, depending on your 00:36:02.680 --> 00:36:06.879 answers to the previous questions. You can work around 00:36:06.880 --> 00:36:10.479 these issues in various ways, like modifying the 00:36:10.480 --> 00:36:15.439 authentication system, or by specifying a script for your 00:36:15.440 --> 00:36:21.799 login shell. But if your normal workflow is to simply log in 00:36:21.800 --> 00:36:25.679 and start Emacs and run that Emacs session until your next 00:36:25.680 --> 00:36:36.979 reboot, then it probably isn't worth the bother. NOTE Resources 00:36:36.980 --> 00:36:41.999 So thank you for listening to my talk, Emacs as a Shell, by 00:36:42.000 --> 00:36:46.319 Christopher Howard for Emacs Conference 2024. 00:36:46.860 --> 00:36:51.519 At the bottom of this page, you can see a link to the 00:36:51.520 --> 00:36:56.919 repository containing the brief amount of code that was 00:36:56.920 --> 00:37:03.679 featured here in this video, as well as a link to my personal 00:37:03.680 --> 00:37:10.279 Gemini gemlog, as well as to a Web portal version of that. 00:37:10.280 --> 00:37:13.000 Thank you.