I realize now, well after digging deep into the T section, that I should have broken apart a lot of the programs listed here and clumped them together in megaposts, like I did with 2048.c.
I’m going to do that again now with a series of applications that are intended to convert terminal output into a replayable format, and beyond. Knowing that, you might correctly infer that there’s not much to show. You would be correct. In other words, no screenshots. 😦
Recording what happens in the terminal is not new. If you remember script, the granddaddy of terminal recorders, you’ll know that this idea has been around for decades, and there’s nothing new in piping the output of your terminal screen (emulated or not) into a recorded session. The novelty comes in the variety of tools that will do it for you.
I intentionally skipped over one of these programs — termrec — a week or two ago. I’ll take care of that one today, and I also have nh_recorder, ttyrec, ttygif and tty2gif, plus a bonus at the end and an online solution to mention. For each one I’ll try to give a quick rundown on the high points and low points, and my overall impression.
Pros: Very light, very transparent. Could be good for extreme cases where nothing else seems to function, or over specific network connections. Cons: Only dumps to a file; needs its counterpart,
nh_player, to replay. No practical control outside editing the code. Seems to only update a line at a time. I.e, no real animation effects, only periodic line-by-line refreshes.
Overall: This might be just a primitive tool intended for use with old versions of NetHack. It works, even if it’s not really practical.
Pros: Supports remote sessions. Can start an application directly, instead of spawning a subshell (a la script). Can append existing recordings. Has playback and timer tools. Cons: Clips the terminal size, which means you may end up with large empty areas if you record ncurses applications. Only sends output to its own format. No compression options.
Overall: This is a step up from nh_recorder, but it’s frightening that it slices away at the terminal area and leaves large black swaths where your application should be. I hope that was something I did wrong. Regardless, it lacks some of the features that the upcoming applications have.
Pros: Converts ttyrec format files into animated gifs, by playing back ttyrec files and using imagemagick‘s import command on them. Cons: Somewhat haphazard in its delivery. Two-step process; ttygif makes a slew of specifically named images, then relies on an included shell script to concatenate them. Final product should be a recording of the terminal session, in gif format. Relies on imagemagick.
Overall: Just too spattered for my liking. Even short recordings create a mess in your directory. The only time I can see where this would be a good approach is if I needed to edit out specific frames of a recording, and even then it would be a chore. Conceivably this could allow some control over frame quality and delay though.
Pros: Automatic compression. Support for ncurses applications. Compatible with ttyrec. Option to append recordings. Will save in several formats. Can jump straight into an application, instead of spawning an additonal shell. Cons: Some screen corruption in playback of ncurses applications. Terminal size clipped. No automatic conversion to gifs.
Overall: This is step up from ttyrec, but it still seems to suffer the two main faults of its predecessor: I’ve seen a lot of corrupted playback, especially with full-screen console applications. And clipping the available recording area makes it only marginally useful to me.
Pros: One tool for the entire process — record, save, and convert. Control over filenames in both the saving and conversion process. Can replay its own binary save files. Automatic conversion to gif, if desired. Cons: Sometimes tricky to play back a file without overwriting it. Relies on imagemagick. No automatic compression. No control over image format, or flags passed to imagemagick. Can eat memory like a pig — I’ve seen it gobble a gigabyte for a 20-second 80×24 recording. Sometimes corrupts the output image, but only very rarely.
Overall: This is the one I use, mostly because it will record the entire terminal area, and generally it doesn’t garble the end result. I have accidentally overwritten a recording while trying to play it back, but the conversion to gif is convenient and thus far without fault (the one time it did create gobbledygook was probably my error). With a few small improvements, this could be the clear winner. If it doesn’t get a handle on memory consumption, it’s not going anywhere though.
The gifs you’ve seen over the past week or so were made with tty2gif, and I’ve more or less implanted it into my system after tinkering with the other four. It’s possible that there are others, but between script and these others, you should be able to find one you prefer.
Now a bonus goodie: termcast
termcast lets you broadcast terminal sessions live, a la twitch.tv or some other streaming video sites. I can’t say that I built up an entire system to show my own terminal sessions — the tools are there for that — but I did watch a game or two of nethack that someone else was playing.
termcast relies on ttyrec for broadcast, but you can watch a game with only telnet. I’m not sure if the same issues with corruption or terminal size persist through termcast. I know I did see some garble in the games I watched, but I assumed that was from differences in terminal environments or something related to telnet.
And as promised, an online solution: showterm.io
I got a link a long time ago to showterm.io but forgot what the name was, making it rather tricky to hunt down. James T. sent me a working link a few weeks ago, so I’ll credit him with the catch.
The showterm client installs through gem or by straightaway downloading the binary from the home page. Recording and uploading a session provides you with a link, which you can use to view the session or share with others.
If I remember correctly, I was able to upload a recording from an X-less machine, but it probably goes without saying that you’ll need some sort of graphical environment to view the link. I tried this quite a while ago, but I seem to remember elinks throwing its hands up in frustration when I fed it the showterm.io page.
I think that’s all for now. Taking these six or seven applications and loading them all on one post has taken a nice chunk out of my list, especially since there’s nothing in particular I can show for them, one by one. 😉
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Based on your feedback, I have improved tty2gif by reducing the output gif file size. Check it out. Thanks for ImageMagick team’s wonderful library!
Next version would be record gif using image stream, instead of holding all intermediate frames in the memory, if I have time…and/or beer…
That would be very helpful. On some machines with less memory, tty2gif was causing them to lock. Thanks for looking into it! 🙂