[Rd] Sys.readlink (on BSD vs Linux)
sven.templer at gmail.com
Mon Feb 29 16:10:25 CET 2016
`Sys.readlink` is returning values as explained/expected.
I was very confused by mixing C library functions with coreutils and not reading careful enough, please excuse me for that.
A link to `normalizePath` would be of help in the 'See Also' section, in my opinion.
> On 29 Feb 2016, at 16:02, Simon Urbanek <simon.urbanek at r-project.org> wrote:
>> On Feb 29, 2016, at 5:59 AM, Sven Templer <sven.templer at gmail.com> wrote:
>> sorry for not being clear enough.
>> My problem is represented with the following code, running on OSX:
>> mkdir ~/test
>> ln -s ~/test ~/testlink
>> touch ~/test/foo
>> Rscript -e 'Sys.readlink(c("~/test/foo", "~/testlink/foo")); normalizePath(c("~/test/foo","~/testlink/foo"))'
>> I expected `Sys.readlink` to show the same output as `normalizePath`.
> Why? To quote from the Sys.readlink() docs:
> A character vector of the same length as ‘paths’. The entries are
> the path of the file linked to, ‘""’ if the path is not a symbolic
> since you are referring to a file and not a link the result is as expected "" - both on OS X and Linux.
>> Also, I think the readlink.h imported to R to be the same as from the system's `readlink` command, thus mimicking the command line difference.
>> Am I wrong with the latter? Anyway, the behaviour is irritating, thus the request to at least mention `normalizePath` in the Rd of `Sys.readlink`.
>>> On 29 Feb 2016, at 11:44, Mikko Korpela <mikko.korpela at aalto.fi> wrote:
>>> On 29.02.2016 10:34, Sven E. Templer wrote:
>>>> Hello together,
>>>> the function `Sys.readlink` uses the system's readlink command to resolve symlink paths. On OSX/BSD the command has a different meaning than on Linux .
>>>> There exists the tool 'realpath', which seems suitable for the task, at least applied at the command line level . It is used in `normalizePath`.
>>>> I suggest (at least the latter) to
>>>> * use realpath instead readlink within Sys.readlink (do_readlink -> do_normalizepath)
>>>> * link to `normalizePath` in the Rd document, eventually mentioning the difference
>>>> Many thanks,
>>>>  see
>>> What do you mean by "different meaning"? How are the command line tools
>>>  relevant when R is using the C function 'readlink'?
>>> Mikko Korpela
>>> Aalto University School of Science
>>> Department of Computer Science
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