> I know about CUPS. There is no real alternative on Linux, is there?
I don't know what lifting "real" is doing here, but lpd(8)[0] (line printer daemon) is what we used to use, and printcap(5)[1] to configure. It was general enough that you could make a music playlist system out of it[2].
Indeed, SQLite started life as simply a Tcl extension[0] that “escaped into the wild”. Redis was initially prototyped in Tcl too, and ‘antirez has nice things[1] to say about Tcl.
I'm curious about why they chose Tcl, particularly over languages like Python or Perl. Were there specific aspects of Tcl that made it appealing for SQLite and Redis, or was the choice more about familiarity with Tcl? Either way, I'd love to understand what they found interesting or advantageous about Tcl in these projects. BTW, I chose Tcl/Tk in the past because it was the easier way I found to quickly built an UI on Unix/Linux.
Most likely for the same reason you found. Once you know it, it's very easy to use, and it's available in most distributions (if not all). So both familiarity with Tcl, while having that ability to build out quick and stable GUI tests, including the lack of churn in the GUI framework. For myself, having to readapt to a GUI framework when I'm just trying to get something visual up and running to make life slightly easier, makes something like Tk much more beneficial for just getting work done. A bit ugly, but anyone technically inclined will figure it out quickly, without constantly having to change up libraries. I only speak for myself and put my 2 cents in, I don't speak for anyone else, but for general tooling targeted at developers it seems perfect.
Both Richard Hipp and Salvatore Sanfillipo came out of the Tcl community. SQLite was originally just a Tcl extension (and may I say, SQLite's Tcl binding is a dream to use). In a nutshell, they were already using Tcl because they found it useful.
> Is there a minimal amount of magic? No; the amount of magic you can do is effectively unlimited.
I might be mistaken, but I think the OP was asking if there is surprising magic (I.e. special cases/considerations) built into the language, in which case I’d say, “No, Tcl is not “magical”, but surprisingly simple and regular.” That said, indeed it’s powerful in its application of its primitives, but you do still need to mind some things (don’t pretend* you can quote better than the quoting engine, don’t pretend* you can do lists better than the list processor, …). Not magical though - very understandable.
*rules are meant to be broken, blah, blah, but the “gotchas” are new practitioners falling into this, or advanced cases, falling into this…
BigIP iRules in F5 network appliances (and A10 appliances)[0], orchestration in Argonne National Labs super computer[1], Tealeaf[2], Python Tkinter[3] …
I use it day to day because it’s got a great balance of Lispyness and simple scriptyness, and a great C interface. It’s got a fine REPL, and can be built up (by writing in C) with extensions that are 100% first-class canonical Tcl, in good part (wholly?) because Tcl is such a simple language[4], and homoiconic[5]. A joy to develop in and use.
i once managed to create a directory named ~ using the mirror tool written in perl.
then i naively tried to remove it using "rm -r ~" and started wondering why removing an empty directory would take so long, until it dawned on me...
i learned a few new habits since then. i almost never use rm -r and i avoid "*" as a glob by itself. instead i always try to qualify "*" with a path, remove files first: "rm dir/*"; and then remove the empty directory. "rmdir dir/"
if i do want to use rm -r, it is with a long path. eg in order remove stuff in the current directory i may distinctly add a path: rm -r ../currentdir/*" instead of "rm -r *"
related, i also usually run "rm -i", but most importantly, i disable any alias that makes "rm -i" the default, because in order to override the -i you need to use -f, but "rm -i -f" i NOT the same thing as "rm". rm has three levels of safety: "rm -i; rm; rm -f". if "rm -i" is the default the "rm" level gets disabled, because "rm -i -f" is the same as "rm -f"
Change your do block to `printf %q\ rm -f "$i" ; echo` and it won't lie about spaces. In case HN has "trimmed" my post in some way, as it often does, that's: percent q backslash space space. Works in bash/zsh, but not dash, probably not whatever your sh is. Can make a function of it trivially, but you have to handle the $# -eq 0 case, return whatever printf returns, etc.
When deleting, if it is more than a few specifically named files I will use a "find ... -delete" invocation.
I like it for two reasons. Find feels like it has more solidly defined patterns and recursion than shell globing and by leaving off the "-delete" it give me a chance to inspect the results before committing to my actions.
Very cool of you to post this. Too many people won't post stories like this, but I've done very similar multiple times. I think it definitely helps reinforce proper habits, and is the best way to cut your teeth on technology. It's also great for anyone new to read something like this, and be able to avoid something so devastating, and maybe make lesser mistakes, but still learn from both!
when you get to be as old as i am, these are the war stories you share with your kids and grandkids around the campfire ;-)
like the one from my colleague who once fat fingered fsck into mkfs and i lost my personal homepage because of it. what makes me uncomfortable about that story is that it was not my fault. if it were it would have been easier to tell. but at the time i was quite frustrated and my colleague felt that despite me trying to not get angry at him. i still feel really bad about my reaction then, adding to his predicament, since he had to live with the guilt about losing our website and everyone's personal home directory. it's bad when a mistake causes you to loose something personal, but so much worse when you loose someone elses stuff.
talking about mistakes is how we learn from them. the important part is not to get embarrassed about them. however that requires an environment where we are not blaming each other when something goes wrong.
i could have made that mistake myself. and i applied this lesson to my own learning as if i had.
blessed be the pessimist, for he hath made backups...
Absolutely, the worst mistakes are the biggest opportunities for learning. Destroying your own files is painful. Destroying EVERYONE'S files is a lesson that is more painful and something you will be more careful not to repeat.
I try to tell as many of these stories in person as possible, to let everyone know that unless you have dealt with this kind of accident, you're either in the 1% or due for your turn. I'd like to think that sharing these stories might at least give someone some pause before they go ahead and throw caution to the wind.
> if "rm -i" is the default the "rm" level gets disabled, because "rm -i -f" is the same as "rm -f"
You can use "\rm" to invoke the non-aliased version of the command. I made "rm -i" the default using an alias and occasionally use "\rm" to get the decreased safety level you described. I think it is more convenient that way.
I love zsh auto completion for this stuff. It automatically escapes really messed up paths like paths with new lines or emojis and crazy characters like that. Its really rare but I still intentionally practiced removing these things just so I can do it safely if it ever happens.
I've long fantasized about a tool I call "expect" that safeguards against crazy stuff like that.
It has a syntax of your expectations, functionally existing as a set of boundaries, and you can hook it to always run as a wrapper for some set of commands. It essentially stages the wrapped command and if none of the boundaries are violated it goes through. Otherwise it yells at you and you need to manually override it.
For instance, pretend I'm ok with mv being able to clobber except in some special directory, let's call it .bitcoin or whatever. (chattr can also solve this, it's just an example). The tool can be implemented relying on things like bpf or preload
Originally I wanted it as a SQL directive ... a way to safeguard a query against doing like `update table set field=value expect rows=1` where you meant to put in the where clause but instead blew away an entire column. I think this would be especially useful surfacing it in frameworks and ORMs some of which make these accidents a bit too easy.
When it comes to SQL, I will often write a SELECT with very explicit search (WHERE) criteria for this very reason. Then copying that statement, commenting the original, and pasting to change into an UPDATE or DELETE statement seems to be a technique that works well for me. The SELECT tells me exactly what I'm going to UPDATE or DELETE, and once I have that, changing the syntax is very minimal. In the case of an ORM, you might have to write a tool that only listens on LOCALHOST to run these statements first.
I always write the where first. It's kinda like thinking in RPN or postfix. I put the parts in out of order in a way that prioritizes the minimization of error.
But this is stupid. These are computers, we can make whatever we want. Executing a delete or update should, if one desires, not have to be database knifeplay.
I know what you mean, I do the same. I agree, but at the same time, it's difficult to start building in protections for the user. Where do you start and where do you stop? I have been forced to do the extreme to protect the user, and then you are asked why things are so difficult to use. I think to make something for someone that concentrates in the technology, as well as a beginner, means you've got to give up so much power (or create a secondary syntax/interface for both audiences). It would be nice to be able to set modes, but then it's going to be database specific unless it has proven itself to be useful across engines. Like most standardization, then you play syntax games between vendors. It would be nice to at least be able to write an UPDATE or DELETE statement with a leading character or keyword to display affected rows.
I understand, but with how much of a change to the language? Such a change would take an enormous amount of time to make it into the ANSI/ISO SQL standard, and what database would start to implement it first, and which would hold out as long as possible?
I don't disagree that it's impossible, but how do you get the syntax standardized at this point? Do you get various dialects, or an agreement between vendors? Look how slowly the standard moves, when do we get this where it's usable in most popular RDBMS?
I have upvoted you for each comment you've made, but I feel like it's not that simple. Even just getting a single vendor to implement it is a huge undertaking. I know that you and I see the value in it, but I don't feel like we're the first to see that. There's a reason behind not implementing this feature, and it's the complexity that lies behind such a feature, like most things. This seems like one of those recursive and interactive features that don't fit into SQL. Does it present the rows that will be updated or deleted, and then ask if you wish to perform the operation? That doesn't work like anything SQL based, and I feel that's why we don't have it. I appreciate the back and forth on this, and am curious as to how you think it should be handled, if there's a way to fit in the way SQL works.
If the expectation is not met then it rolls back and fails. I implemented a slipshod version of it years ago for a previous employer (it got the job done with a lousier syntax)
Sounds like a solid idea, but I feel like just replacing your UPDATE with a SELECT COUNT(whatever_column_is_indexed_from_your_where) would be a good practice. If your DBMS supports an external language, that might be the best idea, so you can write your own logic, while keeping mostly everything in the database itself.
I only mean this from a more ANSI SQL side of things, where you might want to build your skills up to use as much of the standard as possible, until it's no longer possible and make sense to dip into platform specifics. I used to build code around being cross-platform, but at the same time realized that it's more useful to learn the ANSI standard, and then break free with LOTS of useful comments where it makes sense to do things more efficiently and with safety that you don't get normally.
For sql specifically, “limit 2” is my default way to write “expect 1”; if it affects two rows, I know that I have screwed up, whereas “limit 1” can be wrong without my noticing.
because then i become to rely on stuff being in the trash and i'd be less careful when deleting, which means i have to double check when i clean the trash. that's extra work.
. and since the trash is one single folder for the whole desktop, that means the trash is full of stuff from all over the place, making a review extra hard.
in most cases i know something needs to be gone, so i'd rather delete it on the spot.
besides that, the primary reason for deleting stuff is to gain space. moving things to trash doesn't help with that.
what i sometimes do though, when mass deleting, is to move stuff to be deleted into a new folder (usually called "del" or "delete"). then verify the contents of the folder before removing it.
what would be more useful is a kind of trash implementation that does not take space, in that it keeps files around but reports them as unused space that can be overwritten when space is needed. kind of like undelete is possible on some filesystems. so that gone is gone because i can't control when deleted space gets used up, but in a panic situation i can revert the most recent deletes.
I've heard that one of the Unix founding fathers had a directory with 125 files that all had single-byte names: one for each ASCII symbol except slash, dot and null. He would then test any new utility against this directory and chew the careless programmer out if it couldn't correctly handle every one of these names.
Now the big question - was Baratza cool to deal with? I haven’t had too much interaction with them, but I replaced (they sold me) a controller board for my Vario-W for a reasonable price, as well as burrs and the drive. The machines are good for what they are, but their service (what they pride themselves on) is exceptional in my experience.
To be fair, Tcl has Henry Spencer’s regexp[0][1], and is awesome; Postgres also base their regex on Henry’s work for Tcl[2]. Perl is certainly famous for its regex and popularizing thinking of problems in terms of regexes (for better or for worse[3]), but it’s not the only game in town.
>> Perl is certainly famous for its regex and popularizing thinking of problems in terms of regexes (for better or for worse), but it’s not the only game in town.
Agreed.
In that old system we did not have any TCL scripts or third-party libraries--just C, Perl, and C shell (no Bash; it was Unix).
I don't know what lifting "real" is doing here, but lpd(8)[0] (line printer daemon) is what we used to use, and printcap(5)[1] to configure. It was general enough that you could make a music playlist system out of it[2].
[0] https://man.netbsd.org/lpd.8
[1] https://man.netbsd.org/printcap.5
[2] https://patrick.wagstrom.net/weblog/2003/05/23/lpdforfunandm...
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