4 ms·

There's a problem with "command -v," in that it's not actually a command. It's a Bourne shell builtin. You can't use `command -v` in csh or other shells, only

There's a problem with "command -v," in that it's not actually a command. It's a Bourne shell builtin. You can't use `command -v` in csh or other shells, only in Bourne style shells (bash, zsh, etc). /usr/bin/which is a standalone binary. It can be invoked without a shell at all. Many comments discussing `command` being part of POSIX are I think missing that `command` is only part of POSIX insofar as the Bourne shell is defined by POSIX. It is part of a POSIX `/bin/sh` and is not its own thing. Keeping /usr/bin/which is the correct decision and it should probably be added to POSIX.

22c 5y ago
You can use command -v in any POSIX compliant shell. csh is not POSIX compliant. Your list of shells in inexhaustive to the point of being almost misleading. bash and zsh are "heavy-weight" shells, a lot of lightweight shells also support command. If you're specifying your shebang as #!/bin/sh then you should not assume you have access to functions like type or binaries like which, but you can generally assume you have access to the command built-in.
- throwaway09223 5y ago
  Well the point is that it's a shell component, so it's not available from anything other than a shell which is undesirable. I understand Bourne style (POSIX) shells have the vast majority of the market, but the point is breaking other environments. "command -v" is not available everywhere so it is not a viable replacement for /usr/bin/which.
  - 22c 5y ago
    "which" is also not available everywhere, that's how I know about "command -v".
- rascul 5y ago
  > If you're specifying your shebang as #!/bin/sh then you should not assume you have access to functions like type 'type' is actually POSIX though. bash does extend it. https://pubs.opengroup.org/onlinepubs/9699919799/utilities/type.html https://pubs.opengroup.org/onlinepubs/9699919799/utilities/t...

22c 5y ago

You can use command -v in any POSIX compliant shell. csh is not POSIX compliant. Your list of shells in inexhaustive to the point of being almost misleading. bash and zsh are "heavy-weight" shells, a lot of lightweight shells also support command. If you're specifying your shebang as #!/bin/sh then you should not assume you have access to functions like type or binaries like which, but you can generally assume you have access to the command built-in.

throwaway09223 5y ago
Well the point is that it's a shell component, so it's not available from anything other than a shell which is undesirable. I understand Bourne style (POSIX) shells have the vast majority of the market, but the point is breaking other environments. "command -v" is not available everywhere so it is not a viable replacement for /usr/bin/which.
- 22c 5y ago
  "which" is also not available everywhere, that's how I know about "command -v".
rascul 5y ago
> If you're specifying your shebang as #!/bin/sh then you should not assume you have access to functions like type 'type' is actually POSIX though. bash does extend it. https://pubs.opengroup.org/onlinepubs/9699919799/utilities/type.html https://pubs.opengroup.org/onlinepubs/9699919799/utilities/t...