job_start behaves differently than running the command in command line

[ipod825]

Describe the bug
running rm command with job_start behaves differently than running it in the command line.

To Reproduce
First run in command line:

mkdir foo; cd foo; touch a; chmod u-w a;vim --clean

:call job_start('rm a',{'out_cb':{j,d->append(line('.',d))}})
:!ls

Actual behaviour

The file a is deleted without any output being append to the current buffer.

Expected behavior
Because the file a is write protected, rm prompts rm: remove write-protected regular empty file 'a'? in the command line, while it didn't trigger the on_stdout with this prompt.

Environment (please complete the following information):

• Vim version: 8.1.1467
• OS: [5.1.7-arch1-1-ARCH

[ipod825]

Same issue in neovim

[k-takata]

The prompt will be output to stderr, not stdout.

[ipod825]

@k-takata
Changing the command to

:call job_start('rm a',{'err_cb':{j,d->append(line('.',d))}})

Still no output append to the buffer and the file is deleted silently.

[k-takata]

Maybe because stdin is redirected to /dev/null?
The following command deletes the file a silently:

$ rm a < /dev/null

[ipod825]

That's possible. Thought based on the document:

"in_io": "pipe"         stdin is connected to the channel (default)

stdin shouldn't be redirected by default.

Explicitly running
:call job_start('rm a',{'out_cb':{j,d->append(line('.',d))}, 'err_cb':{j,d->append(line('.',d))} , 'in_io':'pipe'})
still not working.

[blueyed]

Using 'pty': 1 makes it work on Neovim - it outputs to stdout then.

[mattn]

You must specify ["rm", "a"] for the first argument instead of "rm a".

[chrisbra]

This is not a bug in Vim. The error message from rm that you see, is only issued, if rm is connected to a tty. See remove.c from coreutils:

https://github.com/coreutils/coreutils/blob/0251229bfd9617e8a35cf9dd7d338d63fff74a0c/src/remove.c#L210-L216

  if (!x->ignore_missing_files
      && ((x->interactive == RMI_ALWAYS) || x->stdin_tty)
      && dirent_type != DT_LNK)
    {
      write_protected = write_protected_non_symlink (fd_cwd, filename, sbuf);
      wp_errno = errno;
}

So only when the stdin is a tty (or the -i option has been used), write_protected will be set and only if it is set, the prompt will be shown later.

You can see the same behaviour when using ssh, compare this:

0 141896 chrisbra@debian ~/temp/foo % touch a && chmod a-w a && ssh  localhost rm $PWD/a
chrisbra@localhost's password:
0 141897 chrisbra@debian ~/temp/foo % ls -l
total 0
0 141898 chrisbra@debian ~/temp/foo % touch a && chmod a-w a && ssh -t  localhost rm $PWD/a
chrisbra@localhost's password:
rm: remove write-protected regular empty file '/home/chrisbra/temp/foo/a'? n
Connection to localhost closed.

You can force this in Vim using the pty argument of job_start().