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Inspect ANSI control codes and escape sequences
- webpro 1y agoWorking with and debugging ANSI control codes and escape sequences can be a challenge. This free web-based tool helps to inspect the input, visualize colors and styling, and list control codes. By using a proper tokenizer and parser (not just regex hacks), it supports all sorts of control codes. The parser is open source and available too (find links in "about"). Type or paste text in the black text area, or try out the examples. Use the lookup table to filter & find specific codes. Feedback welcome, I’d love to know what’s confusing, missing, or especially useful.
- michaelmior 1y agoVery cool! Seems like this should be a Show HN post.
- teddyh 1y agoNo support for blinking text.
- webpro 1y agoThe parser has, but not the HTML renderer indeed. Using a third-party lib for that currently, but noticed the limitations too. Might replace it with my own!
- teddyh 1y agoGreat! Next step: torturetest.vt
- webpro 1y agoThere is https://github.com/webpro/ANSI.tools/blob/main/packages/parser/test/tokenize-stress.test.ts https://github.com/webpro/ANSI.tools/blob/main/packages/pars... and others
- teddyh 1y agoI was thinking of <http://artscene.textfiles.com/vt100/torturet.vt http://artscene.textfiles.com/vt100/torturet.vt>.
- webpro 1y agoThe lexer and parser handled it perfectly first try. The HTML renderer had a few issues though, but it's being rendered reasonably well now. The torture test has been added to the package tests and to the website as an example.
- ForOldHack 1y agoDoes it crash the tester? https://invisible-island.net/ncurses/tctest.htm https://invisible-island.net/ncurses/tctest.htm
- ForOldHack 1y agoBlinking text? You do not know me, but believe me, I have a special skills that I have developed for many years to deal with people like you. And if I find you I will CREOL you.
- teddyh 1y agoBring it on. I’ll feed you your own form, you insignificant NUL character.
- JdeBP 1y agoThe revealing shibboleth is when people call it "ANSI". (-: "ANSI" is what people call it when they are working from paltry and incomplete samizdat doco of how this stuff works, from Microsoft's old ANSI.SYS appendix to its MS-DOS user manual, to innumerable modern WWW sites all repeating received wisdom. The thing to remember is that the "E" in "ECMA" does not stand for "ANSI". * https://ecma-international.org/publications-and-standards/standards/ecma-35/ https://ecma-international.org/publications-and-standards/st... * https://ecma-international.org/publications-and-standards/standards/ecma-48/ https://ecma-international.org/publications-and-standards/st... * https://www.itu.int/rec/T-REC-T.416-199303-I https://www.itu.int/rec/T-REC-T.416-199303-I If you read ECMA-35, you'll find that there's actually a whole system to escape sequences and control sequences. As I pointed out last month, it's often the case that people who haven't read ECMA-35 don't realize that parameter characters can be more than digits, don't handle intermediate characters, and don't grasp how DEC's question mark and SCO's equals sign fit into the overall picture. People who haven't read ECMA-48 and traced its history don't realize that there's subtlety to missing parameters in control sequences. And people who haven't read ITU/IEC T.416 do what many of us did years ago and get 24-bit colour wrong. Twice over. * https://github.com/tattoy-org/tattoy/issues/105#issuecomment-2974687142 https://github.com/tattoy-org/tattoy/issues/105#issuecomment... Other common errors include missing out on all of the other 7-bit aliases for C1 characters. Or not realising that the ECMA-35/ECMA-48 syntax allows for any control sequence to have sub-parameters, not just SGR. Or using regular expressions and pattern matching instead of a state machine. Only a state machine truly handles the fact that in the real world terminals allowed, and enacted, various C0 and C1 control characters in the middle of control sequences, as well as had ways of cancelling or restarting control sequences mid-sequence. * https://github.com/jdebp/nosh/blob/trunk/source/ECMA48Decoder.cpp https://github.com/jdebp/nosh/blob/trunk/source/ECMA48Decode... But it gets even worse for a real world control sequence decoder. In the real world, not only do terminals interpret the same control sequences, and their parameters, differently depending from whether the terminal is sending or receiving them; but several terminal emulators like the one in Interix, rxvt, the one built in to Linux, and even XTerm, send control sequences that not only break ECMA-35 but also conflict with received control sequences. So if one wants to be comprehensive and be cabable of decoding real data, one needs a switch to tell the program whether to decode the character stream as if it is being received by the terminal or as if it is being sent by the terminal. * https://jdebp.uk/Softwares/nosh/guide/commands/console-decode-ecma48.xml https://jdebp.uk/Softwares/nosh/guide/commands/console-decod... Microsoft Terminal tries to do things properly, which many modern terminal emulators and tools do not, and handles this with two distinct entire state machines, one for input and one for output. * https://github.com/microsoft/terminal/tree/main/src/terminal/parser https://github.com/microsoft/terminal/tree/main/src/terminal... I handled it with a few goto statements and a handful of flags. (-: * https://github.com/jdebp/nosh/blob/trunk/source/console-decode-ecma48.cpp#L454 https://github.com/jdebp/nosh/blob/trunk/source/console-deco...
- mnurzia 1y agoNeat tool, I could see this being handy for debugging TUI tools. I noticed that it works with _escaped_ ESC characters ("\x1b", "\u001b", "\033") but it didn't recognize raw ESC characters that I had in my clipboard. It might be useful to support those (maybe highlight them similarly to how VS Code highlights whitespace characters). The characters show up as numbered unicode error glyphs (I'm on Firefox, if that helps)
- ryan-c 1y agoThis is really cool - I've been experimenting with terminal escape sequences recently, and they go deep. Thanks for sharing! Get in touch (email in profile) if you'd like to collaborate.
- webpro 1y agoThanks! It's all open source (including the tokenizer/parser), so feel free come collaborate on GitHub.
- SpaceL10n 1y agoThe things they don't prepare you for in school... I was working at my first job and we had a ColdFusion app that was displaying some data from the database. I get a ticket one day saying our search page would crash when searching for a very specific document. The other 1 million+ documents all loaded fine to our knowledge, so why this one? I was pretty junior back then and feeling mighty defeated as to why I couldn't figure it out. I debugged every single line and condition, trying to find some reason. After ruling out the code as a culprit, I took the data we were loading and placed it into Notepad++. Don't remember why exactly. I was wracking my brain trying to come up with explanation and lazily moving the text cursor left and right through the text, mostly out of boredom and despair. That's when I noticed that I had pressed the right arrow key in my keyboard and the text cursor position hadn't changed! I pressed it again and nothing. Again, nothin. It took eight key presses to move the text cursor from one letter in a word to the adjacent letter. I was utterly bamboozled. Why was the text cursor getting stuck in the middle of this word?! Shortly thereafter, I discovered "Show all hidden characters" setting in the menu. I toggled it and sure enough there were little black boxes with weird three letter strings in them. NUL, ESC, and others - right where my cursor was getting hung up. That was the day I learned about ANSI control characters and the importance of data sanitization.
- txdv 1y agoThere are also zero-space width characters, yeah utf is a rabbit hole
- webpro 1y agoEmojis and other unicode characters may or may not be rendered as a single-width character. I've been splitting hairs and strings. The tool currently counts any unicode character as a single-width one.
- wpm 1y agoSimilarly, I once copied a shell script out of Slack and saw a bunch of red errors from my IDE when I pasted it in. The errors were on every line that had a new line on it. The error was "â: Command not found", despite there being no such character on the line. Pasted it into a hex editor, tracked down the bytes, and while I can't currently remember specifically what the encoding problem was, it was something to do with going between UTF-8 > ISO-8859 > UTF-8 again. I've since aliased `pbpaste | xxd` (macOS, linux has similar CLI tools for working with the clipboard depending on your distro/DE), because weird shit like this comes up more often than I'd care to admit. Last rabbit hole was discovering that in macOS 15, Apple changed one of the the "space" characters in the default Screenshot file names, but only if your Mac is set to use 12-hour time from a normal ASCII 0x20 space, to a Unicode 'U+202F NNBSP' "non-breaking space" between the time and AM/PM, which was causing S3 uploads to fail.
- tronster 1y agoThis is a fantastic web util; bookmarked for the future. I wish I had this when I was making, [Dragon's Oven](https://tronster.itch.io/dragon https://tronster.itch.io/dragon). It was a lot of nights and weekends of tinkering with ANSI codes in Typescript. I learned a lot that surprised me, such as: most modern OS's still don't support 16m colors out of the box and that the default Linux shell doesn't support beyond 16 colors. Also no really good modern ANSI editors out there. I tried bringing back "TheDraw" in DosBOX for some art, but ended up using a mismatch of more modern utilities, false starting one of my own, and working on an image to ASCii/ANSI converter. Maybe it's growing up in the BBS days, but something about ANSI is really charming.
- prometheus76 1y agoTheDraw was a cornerstone of my teenage years. I would log into different BBSs just to see their ANSI welcome screens, then I would try and re-create them to learn the art. It was a unique form of animation and I was hoping you had figured out how to get TheDraw working. I also later used ANSI to make my own cool command line prompts in DOS and later, Linux.
- ForOldHack 1y agoRecreate them? we would steal the stream, save it, run it through a hex editor, while watching it draw in a separate window. It got to be just a work of wonder what people came up with, and then my friend got an Amiga, and those splash screens... omg...
- codesnik 1y agoI wonder how many languages have nice looking "\e" for "\u001b". ruby, perl, bash, anything else?
- 112233 1y ago"\u001b[0m — reset" ... what? Why SGR is not called by name, while, e.g. CUU is? strange... According to which terminal or standard it interperts sequences? Is this tool really helpful? It does look nice! But it does not help with the corneriest cases that would benefit from such tool the most.
- webpro 1y agoGot to start somewhere! Didn't see many examples to get inspired by either. Here's the full table: https://ansi.tools/lookup https://ansi.tools/lookup. This is my initial take on it. Please bring in the corneriest cases! It's open source so bug reports, RFCs and pull requests are most welcome.
- 112233 1y agoThis thing is made out of corner cases: https://www.invisible-island.net/vttest/ https://www.invisible-island.net/vttest/ I am sure capturing it's output will provide endless source of amusement and despair. There are sequences from real terminal (e.g. stuff documented at vt100.net), sequences from ECMA 48 and friends (most of it likely never implemented), and de-facto behaviour of different software. Infamous examples being original windows terminal, rxvt (ugh), linux co nsole, emacs terminal. Most vexing behaviour is background fill on newline, incorrect characters in terminal reports, broken scroll region, inability to write in bottom-right position etc. This project looks fun! But it leads to endless narrow abandoned places. Hopefully you will enjoy the experience!
- wonger_ 1y agoGhostty the terminal emulator has a cell inspector feature along these same lines
- gwbas1c 1y agoI was a teenager when BBS's were popular. I still sometimes think I would enjoy writing an ANSI parser.
- taviso 1y agoI've used the tool sequin in the past to debug issues: https://github.com/charmbracelet/sequin https://github.com/charmbracelet/sequin It worked great for me, seems much easier to debug logs directly in the terminal.
- webpro 1y agoThanks for sharing, haven't seen that one yet. Will see if I can borrow ideas from it.
- FlyingAvatar 1y agoI would have loved this in 1993. Not that I don't now, but I would have had a real use for it then.
- webpro 1y agoAt least I tried to make it look like a 1993 website
- imran9m 1y agoNice. This is helpful for making jenkis ci output colorful!!