4 ms·

> Bash actually has a POSIX compatibility mode. It's partial. A short example is `date&>FILE`. [edited typo] On a POSIX shell, `date` will run in the backgro

by kps 4y ago

> Bash actually has a POSIX compatibility mode. It's partial. A short example is `date&>FILE`. [edited typo] On a POSIX shell, `date` will run in the background and the date will be written to stdout (`date&`) and `FILE` will be created or truncated (`>FILE`). Using `bash --posix`, the date will be written to `FILE`, since the incompatible bashism `&>` still takes priority.

chasil 4y ago
I agree that is ambiguous. If I were writing such a script where I wanted to launch a background process, and then create/truncate a file, I myself would separate them: date & >FILE Bash wouldn't mistake that, but a lot of shell scripts look like line noise and there are situations where bad form is required (quoted in an ssh, for example). Obviously, people wanting the bash functionality in POSIX would: date > file 2>&1 Bash discourages the latter form in my man page, but anyone interested in portability knows how profoundly bad that advice is.
1vuio0pswjnm7 4y ago
Yikes. This is why I do not use bash. Too complicated. For Linux, I added tab autocomplete to dash and use that for both interactive and non-interactive shell instead of bash. Saves keystrokes and bytes. No need to keep typing "#!/bin/sh" into every script.
- chasil 4y ago
  You can compile dash with a line editing library, but it does not come in most packages.
  - 1vuio0pswjnm7 4y ago
    I use libedit. I am used to NetBSD sh; dash is similar, derived from the same source. I wanted dash to behave more like NetBSD sh, so I changed it. Anyway, I am not a huge fan of "packages". (The problems described in this thread are one reason why.) Of course I use packaged binaries in some instances, but normally I only install them when needed, use them and then uninstall them when I am done. I prefer to compile the kernel and userland myself. That includes the shell. Simply compiling dash with libedit does not provide tabcompletion. Need to make some small changes.

by kps 4y ago

chasil 4y ago

I agree that is ambiguous. If I were writing such a script where I wanted to launch a background process, and then create/truncate a file, I myself would separate them: date & >FILE Bash wouldn't mistake that, but a lot of shell scripts look like line noise and there are situations where bad form is required (quoted in an ssh, for example). Obviously, people wanting the bash functionality in POSIX would: date > file 2>&1 Bash discourages the latter form in my man page, but anyone interested in portability knows how profoundly bad that advice is.

1vuio0pswjnm7 4y ago

Yikes. This is why I do not use bash. Too complicated. For Linux, I added tab autocomplete to dash and use that for both interactive and non-interactive shell instead of bash. Saves keystrokes and bytes. No need to keep typing "#!/bin/sh" into every script.

chasil 4y ago
You can compile dash with a line editing library, but it does not come in most packages.
- 1vuio0pswjnm7 4y ago
  I use libedit. I am used to NetBSD sh; dash is similar, derived from the same source. I wanted dash to behave more like NetBSD sh, so I changed it. Anyway, I am not a huge fan of "packages". (The problems described in this thread are one reason why.) Of course I use packaged binaries in some instances, but normally I only install them when needed, use them and then uninstall them when I am done. I prefer to compile the kernel and userland myself. That includes the shell. Simply compiling dash with libedit does not provide tabcompletion. Need to make some small changes.