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I haven’t seen a shell script in ages that was missing the shebang. Is this common in some places? I’ve started to write dash scripts because that seems to be

I haven’t seen a shell script in ages that was missing the shebang. Is this common in some places? I’ve started to write dash scripts because that seems to be reasonably posix and bash on macOS is ancient.

IggleSniggle 5y ago
I don’t think I’ve ever seen a script written without the shebang. Btw, you can get around the ancient bash in macOS by installing a more modern bash and invoking with /usr/bin/env bash as your shebang. Not sure if that’s a great idea, mind you, but if you’re already writing scripts in something non-portable, it’s an option.
- traviscj 5y ago
  Yeah thing $T _might_ (but probably won’t) happen, so the idea is automatically terrible.
- maccard 5y ago
  There are hundreds of sh files on github that don't have a shebang. Just because you don't write them and your colleagues don't doesn't mean they don't exist in the wild.
  - IggleSniggle 5y ago
    I didn’t mean to imply that they didn’t exist nor that it might not be important to account for them in some contexts. I meant only to convey my own personal experience: that it had never occurred to me that I might need to account for a missing shebang, since providing an interpreter for a script via shebang is all I have ever personally encountered.
  - pxc 5y ago
    wait how does the OS even invoke an interpreter without a shebang? If you have to explicitly call an interpreter when you invoke it, then it's no extra work to call bash some_script.sh anyway
    - IggleSniggle 5y ago
      As I’ve learned in response to this thread, apparently some (but not all) Unixy OSes will run a file marked as executable using /bin/sh if no shebang is supplied.
      - pxc 5y ago
        Oh right, I think that's part of how APE[1] works. But I thought the Thompson shell was old and weird, and that it might not support what people use when they write ‘POSIX’ shell scripts nowadays. Anyway it sounds like in that case the OS _doesn't_ know how to run the script, it just assumes `/bin/sh` will do. I always assumed that scripts without an interpreter line were like snippets to be invoked via `source`, from some shell script with knowledge of the context in which it should be used. Anyway, if that's the way it works, the behavior actually isn't a problem for users of Nushell or Elvish or Fish or anything else, since their executables are never installed to `/bin/sh` anyway. Nushell probably gets installed to `/usr/bin/nu`, Fish to `/usr/bin/fish`, and `elvish` can be installed anywhere. So it's still not clear that there's a real problem with un-shebanged scripts when it comes to using a boutique shell for login. — 1: https://justine.lol/ape.html https://justine.lol/ape.html
maccard 5y ago
Any random blog post that you find with instructions to run something in a shell that uses a variable just won't work copy and pasted, you now need to either modify them for your esoteric shell, or wrap them in a script to be ran through bash

IggleSniggle 5y ago

I don’t think I’ve ever seen a script written without the shebang. Btw, you can get around the ancient bash in macOS by installing a more modern bash and invoking with /usr/bin/env bash as your shebang. Not sure if that’s a great idea, mind you, but if you’re already writing scripts in something non-portable, it’s an option.

traviscj 5y ago
Yeah thing $T _might_ (but probably won’t) happen, so the idea is automatically terrible.
maccard 5y ago
There are hundreds of sh files on github that don't have a shebang. Just because you don't write them and your colleagues don't doesn't mean they don't exist in the wild.
- IggleSniggle 5y ago
  I didn’t mean to imply that they didn’t exist nor that it might not be important to account for them in some contexts. I meant only to convey my own personal experience: that it had never occurred to me that I might need to account for a missing shebang, since providing an interpreter for a script via shebang is all I have ever personally encountered.
- pxc 5y ago
  wait how does the OS even invoke an interpreter without a shebang? If you have to explicitly call an interpreter when you invoke it, then it's no extra work to call bash some_script.sh anyway
  - IggleSniggle 5y ago
    As I’ve learned in response to this thread, apparently some (but not all) Unixy OSes will run a file marked as executable using /bin/sh if no shebang is supplied.
    - pxc 5y ago
      Oh right, I think that's part of how APE[1] works. But I thought the Thompson shell was old and weird, and that it might not support what people use when they write ‘POSIX’ shell scripts nowadays. Anyway it sounds like in that case the OS _doesn't_ know how to run the script, it just assumes `/bin/sh` will do. I always assumed that scripts without an interpreter line were like snippets to be invoked via `source`, from some shell script with knowledge of the context in which it should be used. Anyway, if that's the way it works, the behavior actually isn't a problem for users of Nushell or Elvish or Fish or anything else, since their executables are never installed to `/bin/sh` anyway. Nushell probably gets installed to `/usr/bin/nu`, Fish to `/usr/bin/fish`, and `elvish` can be installed anywhere. So it's still not clear that there's a real problem with un-shebanged scripts when it comes to using a boutique shell for login. — 1: https://justine.lol/ape.html https://justine.lol/ape.html

maccard 5y ago

Any random blog post that you find with instructions to run something in a shell that uses a variable just won't work copy and pasted, you now need to either modify them for your esoteric shell, or wrap them in a script to be ran through bash