-T option help text
Philip Rowlands wrote: On Sun, 30 Aug 2009, James R. Van Zandt wrote: For the help text, here are some alternatives: if DEST is a directory, then delete it first This isn't what -T does. If DEST is an empty directory then it's overwritten with the rename(2) system call. Otherwise mv will fail e.g. if SOURCE isn't a directory or DEST is non-empty. Let's see... vanzandt:/tmp$ date source vanzandt:/tmp$ mkdir dest vanzandt:/tmp$ mv -T source dest mv: cannot overwrite directory `dest' with non-directory vanzandt:/tmp$ rm -rf dest vanzandt:/tmp$ touch test vanzandt:/tmp$ mv -T source dest vanzandt:/tmp$ I agree my proposed help text is wrong. However, I think the current description in the info file is wrong too. It says Do not treat the last operand specially when it is a directory or a symbolic link to a directory. Yet, this is an example where mv fails when DEST is a directory, and succeeds when it is a normal file. So a directory *is* treated differently. The extended discussion on the Target directory page says: For example, when the command `mv /tmp/source /tmp/dest' succeeds, there is no guarantee that `/tmp/source' was renamed to `/tmp/dest': it could have been renamed to `/tmp/dest/source' instead, if some other process created `/tmp/dest' as a directory. However, if `mv -T /tmp/source /tmp/dest' succeeds, there is no question that `/tmp/source' was renamed to `/tmp/dest'. I read the last sentence as saying /tmp/source would get renamed as /tmp/dest whether or not some other process had previously created /tmp/dest as a directory. The fact that it fails instead certainly should be stated. (To me it seems a much less useful behavior.) - Jim Van Zandt
Re: -T option help text
On Sun, 30 Aug 2009, James R. Van Zandt wrote: For the help text, here are some alternatives: if DEST is a directory, then delete it first This isn't what -T does. If DEST is an empty directory then it's overwritten with the rename(2) system call. Otherwise mv will fail e.g. if SOURCE isn't a directory or DEST is non-empty. This is short, but doesn't handle the case of DEST being a symbolic link if DEST is a directory, or a symbolic link to a directory, then delete it first This isn't what -T does either. If DEST is a symlink it isn't deleted, merely clobbered by mv. It's the difference between rename(file, DEST/file) = 0 and rename(file, DEST) = 0 For the short --help description I'd try something like disable special directory handling for DEST Cheers, Phil
-T option help text
Kamil Dudka wrote: On Sunday 30 of August 2009 03:11:34 James R. Van Zandt wrote: ...(I'd first have to check the help printout to see that it's not -T I wanted after all. Then check the info page, because the -T description is so unhelpful. But that's a separate issue.) What exactly is unhelpful on the -T description? We'll be happy to improve the description if you come with something better. The current help entry is: -T, --no-target-directorytreat DEST as a normal file A long option is supposed to be more or less self documenting, but this long option doesn't tell me anything. I find myself asking No target directory? But there's *always* a target directory! I find the help text pretty obscure too. Of the various things DEST could be besides a regular file (symbolic link, device, pipe...) what would it mean to treat it as a regular file? After reading the info page, I have to admit that the help text is technically correct. However, if it can't be understood without reading the info page, then it is not doing its job. For the help text, here are some alternatives: if DEST is a directory, then delete it first This is short, but doesn't handle the case of DEST being a symbolic link if DEST is a directory, or a symbolic link to a directory, then delete it first correct but wordy if DEST exists, then delete it first (even if it's a directory) I prefer this. I'd really like to change the long option too. It should not be saying there is no target directory but rather that the second operand is not naming a target directory. A couple possibilities: --rm-target-first --rm-dest-first However, I am not really happy with either one. - Jim Van Zandt
