3 ms·

Bash is shipped in Debian/Ubuntu, but as /bin/bash, not as /bin/sh. What is shipped as /bin/sh is described here: http://gondor.apana.org.au/~herbert/dash/ ht

by chasil 4y ago

Bash is shipped in Debian/Ubuntu, but as /bin/bash, not as /bin/sh. What is shipped as /bin/sh is described here: http://gondor.apana.org.au/~herbert/dash/ http://gondor.apana.org.au/~herbert/dash/ From the EPEL RPM: "DASH is a POSIX-compliant implementation of /bin/sh that aims to be as small as possible. It does this without sacrificing speed where possible. In fact, it is significantly faster than bash (the GNU Bourne-Again SHell) for most tasks."

John23832 4y ago
Hm but the default shell is still bash. It would make sense that "bashisms" don't work on "sh". You should use bash or bash derivatives (zsh) for bashisms. I think the bigger stumbling block is that people often can't differentiate bashisms from basic shell scripting.
- gdavisson 4y ago
  bash is the default interactive shell for users, but dash is the default shell for scripts with a #!/bin/sh shebang (or no shebang, unless they're run from bash), system() calls, etc. This means bashisms will work sometimes, which can be worse than not working at all. I agree about the importance of differentiating bashisms from basic scripting, but I think the root cause of that is documentation (including this book) that don't make the distinction.
  - layer8 4y ago
    The book is very clear about the fact that it’s using Bash, even noting when a feature requires a newer version, and uses #!/bin/bash for scripts throughout.
  - John23832 4y ago
    ...But the foreword for any script could just as easily be `#!/bin/bash`... you're choosing not to use bash. If you're on a system with no bash, and are forced to use `sh`, then just don't use bashisms... I'm not trying to be difficult, but I just don't see a problem. Explicitly use bash (or a derivative) if you want bashisms, don't if you do not.
- quesera 4y ago
  FWIW, zsh is not a bash derivative. Both are spiritual descendants of Bourne shell directly, with some ksh, csh, and tcsh mixed in, in varying proportions.
  - wyclif 4y ago
    Yes, a lot of people don't realise that bash (1989) and zsh (1990) are almost the same age and were parallel projects, not derivative.
  - John23832 4y ago
    True, what I really mean was bash compatibility

by chasil 4y ago

John23832 4y ago

Hm but the default shell is still bash. It would make sense that "bashisms" don't work on "sh". You should use bash or bash derivatives (zsh) for bashisms. I think the bigger stumbling block is that people often can't differentiate bashisms from basic shell scripting.

gdavisson 4y ago
bash is the default interactive shell for users, but dash is the default shell for scripts with a #!/bin/sh shebang (or no shebang, unless they're run from bash), system() calls, etc. This means bashisms will work sometimes, which can be worse than not working at all. I agree about the importance of differentiating bashisms from basic scripting, but I think the root cause of that is documentation (including this book) that don't make the distinction.
- layer8 4y ago
  The book is very clear about the fact that it’s using Bash, even noting when a feature requires a newer version, and uses #!/bin/bash for scripts throughout.
- John23832 4y ago
  ...But the foreword for any script could just as easily be `#!/bin/bash`... you're choosing not to use bash. If you're on a system with no bash, and are forced to use `sh`, then just don't use bashisms... I'm not trying to be difficult, but I just don't see a problem. Explicitly use bash (or a derivative) if you want bashisms, don't if you do not.
quesera 4y ago
FWIW, zsh is not a bash derivative. Both are spiritual descendants of Bourne shell directly, with some ksh, csh, and tcsh mixed in, in varying proportions.
- wyclif 4y ago
  Yes, a lot of people don't realise that bash (1989) and zsh (1990) are almost the same age and were parallel projects, not derivative.
- John23832 4y ago
  True, what I really mean was bash compatibility