bug#33125: the destrustive and non predent behavior of ALL UNIX commands

[Bernhard Voelker]

On 10/23/18 11:46 AM, address@hidden wrote:
> Hello, 
> 
> I just destroyed 3 days of scaninng work. This was the command: 
> 
> ls p.*.png | sort -t. -k2 -n | gawk '{ printf("mv '\''%s'\'' '\''p. 
> %d.png'\''\n", $0, NR+6) }' | bash [ mailto:address@hidden ] 
> 
> The problem was that the sequence of mv command resulted in one .png file: 
> 
> mv 'p. 123.png' 'p. 124.png' 
> mv 'p. 124.png' 'p. 125.png' 
> mv 'p. 126.png' 'p. 127.png' 
> 
> The result is that you end up with one file: 'p. 127.png'. 

outch, sorry for your loss.

> When you look at the commands (without the trailing bash), you think it's ok 
> because you think declaratively. However, this thing works 
> imperative/procedural. 

As you said, the problem originated from a logic error in the counting
for the new names of the files.
Didn't you run that without the executing "| bash" first?

> I would not have lost all my files if I would have used "mv -i": 
> 
> ls p.*.png | sort -t. -k2 -n | gawk '{ printf("mv -i '\''%s'\'' '\''p. 
> %d.png'\''\n", $0, NR+6) }' | bash 

No, because once you would have confirmed the -i prompt, the same would have 
happened.
The point is to recognize that file 123 is first renamed to 124, then 124 is 
renamed
to 125, and so on.

> ============================== 
> 
> With the rm command it is the same. It deletes/removes, and the file is gone 
> forever. No tracing back option like a recycle bin under Windows. 
> 
> In this mail I make a plei for a more protective manner for the coreutils. 
> The "-i" options should dissapear altoghether and being the default. Instead 
> there should be options to force execution without confirmation. 

The GNU coreutils are a low-level tool set which adheres to certain
standards and provides certain compatibility with other implementations.
We cannot (and therefore will not) simply change such behavior.
Furthermore, -i is not effective in scripts without stdin (in this case
stdin came from the pipe).
Finally, as written above, -i would *not* have helped you unless you
would have seen the logical mistake.

As such, I'm afraid we can not do something at this point.

> Also: 
> 
> 
>     * There should be a recycle bin for rm. 
>     * There should be a call back facility to undo the latest action. In 
> Windowds this is ctrl z. 

Different topic.
I think this has been already discussed.  Again, the GNU coreutils as command 
line
tools are quite low-level, and things like a recycle bin belongs to desktop 
apps.

I'd compare it with using a sharp Japanese kitchen knife: of course one can cut 
oneself
into the fingers, but if one uses it as it's designed for, then it can do things
one can't with a blunt, old steel knife (although the latter may or may not have
its merits regarding other aspects).

Have a nice day,
Berny