'!' 是什么意思？当它被添加到 ex 命令时真的会做吗 (:wq! | :w! | :q! )？

Question

我明白这意味着强制做某事。

这样做时$ vim -R file我进入read-only模式，但这仅作为预防模式起作用

-R  Readonly mode.  The 'readonly' option will be set for all the
    files being edited.  You can still edit the buffer, but will
    be prevented from accidentally overwriting a file.  If you
    forgot that you are in View mode and did make some changes,
    you can overwrite a file by adding an exclamation mark to
    the Ex command, as in ":w!".  The 'readonly' option can be
    reset with ":set noro" (see the options chapter, |options|).
    Subsequent edits will not be done in readonly mode.  Calling
    the executable "view" has the same effect as the -R argument.
    The 'updatecount' option will be set to 10000, meaning that
    the swap file will not be updated automatically very often.

但我还不能理解的是，即使文件的所有者是root用户，它也会指示跳过权限，此外它还更改所有者和组。

Answer 1

!通常意味着您对“强制”的期望，但对于特定命令的含义取决于命令。在 的情况下w!，如果 Vim 由于某种原因无法写入文件，它将尝试删除并使用当前缓冲区的内容创建一个新文件。

考虑以下示例（观察 inode 编号）：

$ touch foo
$ chmod -w foo
$ stat foo
  File: ‘foo’
  Size: 0           Blocks: 0          IO Block: 4096   regular empty file
Device: 22h/34d Inode: 10396141    Links: 1
Access: (0444/-r--r--r--)  Uid: ( 1000/ muru)   Gid: ( 1000/ muru)
Access: 2015-09-10 00:24:28.259290486 +0530
Modify: 2015-09-10 00:24:28.259290486 +0530
Change: 2015-09-10 00:24:30.771263735 +0530
 Birth: -
$ vim -c 'r!date' -c 'wq!' foo
$ stat foo                    
  File: ‘foo’
  Size: 30          Blocks: 8          IO Block: 4096   regular file
Device: 22h/34d Inode: 10396151    Links: 1
Access: (0444/-r--r--r--)  Uid: ( 1000/ muru)   Gid: ( 1000/ muru)
Access: 2015-09-10 00:24:37.727189657 +0530
Modify: 2015-09-10 00:24:37.731189614 +0530
Change: 2015-09-10 00:24:37.763189273 +0530
 Birth: -
$ cat foo
Thu Sep 10 00:24:37 IST 2015

这就是所有者和组更改的原因。权限被保留 - :h write-permissions：

                                                    write-permissions
When writing a new file the permissions are read-write.  For unix the mask is
0666 with additionally umask applied.  When writing a file that was read Vim
will preserve the permissions, but clear the s-bit.

如果你想让 Vim 拒绝写入，请参阅:h write-readonly：

                                                    write-readonly
When the 'cpoptions' option contains 'W', Vim will refuse to overwrite a
readonly file.  When 'W' is not present, ":w!" will overwrite a readonly file,
if the system allows it (the directory must be writable).

请注意，它说“目录必须是可写的”——因为没有可写的目录，Vim 既不能删除也不能创建新文件。