Unix didn't use to support '#!', a brief history

https://utcc.utoronto.ca/~cks/space/blog/unix/ExecAndShebangHistory

by zdw • 4 years ago

87 62 4 years ago

utcc.utoronto.ca

hgazx• 4 years ago

Off topic: why isn’t it “didn’t use”?

ketralnis• 4 years ago

They're both fairly common https://trends.google.com/trends/explore?date=all&geo=US&q=%...

tjader• 4 years ago

"used to" alone is correct in many situations, "didn't used to" is considered wrong by prescriptivists.

Including the "didn't" in the search shows that it's still close though: https://trends.google.com/trends/explore?date=all&geo=US&q=d...

js2• 4 years ago

It is. "Didn't /used to/" is a mistake in American English, according to prescriptivists anyway:

https://www.merriam-webster.com/words-at-play/is-it-used-to-...

wyattpeak2• 4 years ago

EDIT: Never mind, sorry, I missed part of the article, it does indeed say what you say.

---

That's the opposite of what your source says:

In writing, however, use to in place of used to is an error.

Used to X was the standard past tense of to use in the sense of being in the habit of:

I used to fish: I was previously in the habit of fishing, correct both in the past and today.

I use to fish: I am presently in the habit of fishing, correct in the past but no longer understood today.

The second, however, is according to MW occasionally misused to mean "I was previously in the habit of fishing".

swatcoder• 4 years ago

Garner’s Modern English Usage (4th edition) acknowledges didn’t used to as “fully accepted” (Stage 5) and notes that it was almost twice as common in journalistic usage.

There’s long been open debate among linguists about what might be formally more correct, but with sound arguments on both sides. It mostly comes down to grammatical rule vs idiomatic phrase with a strong validating history.

That said, he suggests never used to as a way to escape the grammar debate while still keeping used.

lttlrck• 4 years ago

Either seem awkward to me, esp. when written, I'd prefer "didn't always support".

decremental• 4 years ago

Classic HN. One comment about the article. Nine comments about the title.

user3939382• 4 years ago

Or nine comments about the scrollbar behavior or design of the content.

cduzz• 4 years ago

Unix has lots of weird cruft littering its dark corners; for instance you can use : instead of #! and, if I remember correctly, the OS will use "the default shell".

Similarly, you can have your shell in the GECOS field be null, and again, you'll get the default shell. I think I had a bug report in with Sun complaining that XDM or the fancy XDM replacement didn't work correctly with a null shell value. Or maybe it didn't work if you had the character "ctl-l" as your password.

It's been a while. In any case, don't do these things.

fsckboy2• 4 years ago

for instance you can use : instead of #! and, if I remember correctly, the OS will use "the default shell"

when I learned unix around 1980, you had to start a shell script file with a single # on a line by itself, and there was no bang option... but I want to say there was a way to select sh vs csh, though I can't recall it... maybe you had to start with a couple lines of Bourneshell, and that part would relauch csh on the same file. can't remember though. A dozen years later that was a common technique to launch perl scripts tho I don't recall why.

iforgotpassword• 4 years ago

Unix has lots of weird cruft littering its dark corners; for instance you can use : instead of #! and, if I remember correctly, the OS will use "the default shell".

I mean, it's basically what the article says. Anything that's not an executable and doesn't start with "#!" gets passed to the default shell. ":" is no exception here.

jjgreen2• 4 years ago

Unix has lots of weird cruft littering its dark corners

Indeed it does -- try logging in to your Linux machine with your username in all-caps :-)

GekkePrutser• 4 years ago

That does have a specific reason, it's not an arbitrary old thing. It's to support terminals that don't do lowercase. Like some old terminals such as Dec VT05 or TTYs (the ones that printed on paper often didn't support this or they had a mode-switch character for it rather than separate characters)

Old as it is, I'm sure these are still around in some production environments.

HillBates• 4 years ago

Unix didn't used to support VIM

throw0101a2• 4 years ago

The Prophet Unix needed to come first to make the way ready for the Messiah Vim.

divbzero• 4 years ago

The name for #! must have originated as hashbang which was abbreviated as ’shbang and then later gained an e to become shebang?

vhasus• 4 years ago

I always thought it was sharp bang = shabang

jjgreen2• 4 years ago

Sharp's a different thing, ♯ against #, it always amuses me that Microsoft's version of Java should be called C♯ when their OS has such dreadful support for Unicode that it's almost universally written C#, so C-hash (or C-pound for you left-ponders).

2143• 4 years ago

Where I'm from:

"#" => "hash" (never had I heard it being called "pound")

"!" => "exclamation mark/point" (never had I heard it being called "bang")

So to me "#!" was "hash exclamation" in my college in home-country.

Then I went to USA for an exchange program, where people consistently called it "she bang" and "pound bang". Took me a while to get it.

dfawcus• 4 years ago

Or even 'hash pling'.

anttiharju• 4 years ago

never had I heard it being called "bang"

DuckDuckGo also calls exclamation points bangs https://duckduckgo.com/bang

adhesive_wombat• 4 years ago

I first heard "bang" for "!" in the context of "interrobang" (‽).

Notably I seem to recall I first encountered it as the symbol found on the forehead of Barry Trotter, a parody Harry Potter published in 2001.

throw0101a2• 4 years ago

"!" => "exclamation mark/point" (never had I heard it being called "bang")

Used in Unix-y circles since at least the 1980s, where "bang paths" were used for UUCP routing:

* https://en.wikipedia.org/wiki/UUCP#Mail_routing

* http://www.catb.org/jargon/html/B/bang-path.html

Maursault2• 4 years ago

Hash is extremely contemporary, newer than number, and still a nickname. Pound is older, but it's true proper name is octothorpe.

contradictioned• 4 years ago

Or in Germany, it's sometimes called "Lattenzaun" (lattice fence)

fsckboy2• 4 years ago

the word "shebang" was a common word in the middle of the last century, so with exclamation point being bang, and i think more likely, shell starting with "sh", it was undoubtedly straight up selected because of the match to the word. "If you put a script in a file and start it with a hash and make it executable, /bin/sh will run the whole shebang for you" would be an accurate use of the word shebang. A similar bit of slang would be "/bin/sh will run the whole shootin' match for you"

dylan604• 4 years ago

the word "shebang" was a common word in the middle of the last century,

taking just that part of the sentence out of context, that almost reads like some historical tome or some fantasy novel. or maybe it's that i lived a good chunk of the middle of last century and this kind of thing makes realize i've been doing this a lot longer than i'd like to admit

c3534l• 4 years ago

Doubt it. Hash was a pretty uncommon name for # until Twitter introduced hashtags.

robin_reala• 4 years ago

In en-US, sure. But it was basically the only usage in en-GB, due to £.

IncRnd• 4 years ago

Not really. Many people called # the crosshatch, hatch mark, or hash mark. Twitter was late to the game.

dtgriscom• 4 years ago

Whenever I'm about to start a bash script, I have to say "shebang" in my head to remember which goes first: the "#" or the "!".

AceJohnny2• 4 years ago

This reminds me of a bug in macOS that for a while caused our builds to fail once or twice a month with something like "/bin/sh: /bin/sh: cannot execute binary file"

This was because sometimes, the kernel would fail to execute a binary for some reason (this was the core bug), returning ENOEXEC to the libc, which, dutifully, would pass it on to the shell as documented in the article. Of course since the failed executable was a real binary, not a script, the shell would fail with the above error.

I haven't encountered the bug in a couple years, so I guess they finally fixed it. Silently.

cat_plus_plus• 4 years ago

For eunuchs it would be... never mind.

mastazi• 4 years ago

Non native speaker here, it's the second time this week[1] that I see "didn't used to..." instead of what I believe to be the correct form "didn't use to...".

Aren't verbs after "did/didn't" always supposed to be in the present tense? For example you would say "I didn't see you last night" rather than "I didn't saw you last night". Is there a grammatical rule I'm missing?

[1] the other one was this video by youtuber Vsauce, https://www.youtube.com/watch?v=vjqt8T3tJIE

EDIT: wow so many interesting responses, thank you!

bowsamic2• 4 years ago

https://www.merriam-webster.com/words-at-play/is-it-used-to-...

This article says that in American English it’s considered an error, but it’s accepted in British English

I think that “used to” is the form seen so often that “use to” just looks and sounds weird to me. I would never use it

bobbylarrybobby• 4 years ago

I'm American, and I'd also write "didn't used to". The hard 's' necessitates the 'd', otherwise it'd be pronounced "yooz"

Izkata2• 4 years ago

Over at the English Language Learners [0] Stackexchange, reading through the answers and how they describe their references (I didn't click through to read those references), it seems like "didn't used to" is more acceptable in general for both American and British English, even though it shouldn't be correct because it breaks the rules.

I like this last part of one of the answers in particular:

One of the strongest arguments against treating used to as a standard verb form is the pronunciation. According to the Cambridge Dictionary, with the verb form of use, the s is voiced /juːz/ whereas in the noun form it is not voiced /juːs/. In I used to and I didn't used to, the s is unvoiced. It's definitely not a noun, but it is also not a standard verb form: it is something unique, and that's what upsets the grammarians.

Aside, like sibling comment, I'm also a native American English speaker and it's always been "didn't used to".

[0] https://ell.stackexchange.com/questions/100674/didnt-use-to-...

Pinus• 4 years ago

The M-W article says that "it appears to have won some measure of acceptance" in en_UK, and quotes the Daily Mail for an example...

zabzonk• 4 years ago

As a native UK speaker, for me it has always been "used to" and "didn't use to", although up to this moment I have never noticed the subtle difference.

htyden• 4 years ago

I'm also a non-native English speaker, I also found the the title of the linked article weird and also saw the title of the Vsauce video recently. This all made me confused and I'm happy that you brought it up here and that people chime in to clear the situation up.

Tsiklon• 4 years ago

I suppose a clearer way to say this was "Unix didn't always support the shebang."

TimTheTinker• 4 years ago

Justine Tunney's APE (actually portable executables) exploits, er, makes use of, the fact that a shebang isn't required to run a shell script.

The single executable file generated by the Cosmopolitan linker creates an insane polyglot binary executable that runs on 6 operating systems as well as on bare metal (i.e. bootable as its own OS); in addition, it's a valid Zip archive, and you can modify files inside it using any zip utility... fascinating stuff. On Linux, it bootstraps execution initially as a shell script, but the shell script writes the "ELF" file header and executes it (I'm probably doing a horrible job of explaining though).

https://justine.lol/ape.html

If you're interested in learning more, this talk from 2021 is fascinating: https://www.youtube.com/watch?v=1ZTRb-2DZGs. It covers Redbean, a portable, run-anywhere web server built with the APE toolchain; since then Redbean 2 has been released, which adds a lot more features. Here's a link to Redbean: https://redbean.dev/

easrng• 4 years ago

If you want a simpler polyglot, here's a sh/bat to get you started:

  REM=;echo hello from sh;exit#
  echo hello from cmd

jsymolon• 4 years ago

With all the shabang, shebang, splatping going on ... someone might stumble upon the magic word and turn into Captain Marvel.

amelius• 4 years ago

Why isn't this in the file's metadata?

skissane2• 4 years ago

Because Unix's file metadata was traditionally very simplistic – and while many contemporary Unix-like systems do better–such as with extended attributes (xattrs)–that feature came historically late enough that it has never seen anywhere near as much use as it would have had it been implemented earlier.

I think the designers of Unix were (in part) reacting to some systems they'd experienced (such as IBM mainframes) which had very rich–yet complex, cumbersome and rigid–file metadata, and in reaction decided to make file metadata as simple as possible. The idea that you could support richness with simplicity (extended attributes as arbitrary name-value pairs, leaving the name and value format mostly up to applications) didn't seem to emerge until much later. I could be wrong about this, but I think contemporary Unix-like systems actually borrowed the idea from OS/2 (which in turn was possibly somewhat influenced by classic Mac OS resource forks)

bigbillheck• 4 years ago

Runs contrary to the unix philosophy.

yencabulator• 4 years ago

My favorite unix shebang related oddity:

    #!/usr/bin/env
    echo This might not do what you thought.

Unix didn't use to support '#!', a brief history

Related Stories