Re: 'tr' strange behaviors with '-t'

[Pádraig Brady]

On 22/10/2023 00:46, Eduardo Mezêncio wrote:
> Greetings,
>
> I would like some help to understand if some behaviors of 'tr' are bugs or just 
> the intended behavior.
>
> # First case
>
> Consider `echo aaabcc | tr -ds bc a`:
>    It outputs `a` as expected, because it deletes `b` and `c` and squeezes 
> `aaa` to a single `a`.
>
> Now consider the same command including `-t`, `echo aaabcc | tr -dst bc a`:
>    The result is the same, `a`, but I expected it to be `acc`, because `bc` 
> would be truncated to the lenght of `a`, resulting in `b`, so `b` should be 
> deleted and `a` squeezed, resulting in `acc`
>
> # Second case
>
> Consider `echo aaabcc | tr -c a _`:
>    It outputs `aaa___` as expected
>
> Now the same with -t, `echo aaabcc | tr -ct a _`:
>    I expected it to output the same thing, because `-t` should make no 
> difference in this case, but it outputs `aaabcc`, same as the input

-t is there mainly to provide compat with System V tr operation.
The full manual also states that -t is only significant with translation,
which explains the first case at least.
In the second case it depends on the order of operations,
but I expect this is compat with System V operation
(which I don't have access to to confirm at present).

cheers,
Pádraig