[R] Get background colour of terminal

[Jan van der Laan]

Thanks. I am not completely sure what you mean with "You can capture 
stdin using system()". How? I had another look at the documentation of 
system and could not figure out how to do this with system.

I know this is really system/terminal specific. Finding out how to 
determine the capabilities of the terminal is another thing on my todo 
list, but I first want to get this to work on my own terminal for which 
I know the capabilities.

Jan




On 21-02-2022 11:15, Jeff Newmiller wrote:
> You can capture stdin using system(), but you should be cautious as this whole mechanism is highly OS-and-configuration-specific. R is not always running connected to a terminal, and not all terminals respond to the same escape commands.
> 
> On February 21, 2022 1:25:05 AM PST, Jan van der Laan <rhelp using eoos.dds.nl> wrote:
>>
>>
>> I am trying to get the background colour of the terminal R is running
>> in. There is a xterm control sequence for that: running the following in
>> a suitable terminal returns the background colour:
>>
>> cat("\033]11;?\033\\")
>>
>> Except that the result is written to stdin and I can't seem to figure
>> out how to get that into a variable in R.
>>
>> Following a shell script example from stackoverflow [1], I had a little
>> bit of success using
>>
>> cat("\033]11;?\033\\")
>> Sys.sleep(1)
>> bg <- readLines(n=1)
>>
>> where one has to press an enter manually, but this is not something that
>> can be put into a function.
>>
>> Wrapping that shell script into a system call works. That does introduce
>> some dependencies, but on systems where this is relevant sh and sed are
>> probably present anyway. But I still would prefers an R-solution.
>>
>> Does anyone know how one can get the background colour of the terminal R
>> is running in?
>>
>> Suggestions other than using the xterm control sequence are, of course,
>> also welcome. Perhaps a c-routine that can be wrapped into a Rcpp-call?
>>
>> Thanks for the help.
>>
>> Best,
>> Jan
>>
>>
>>
>> [1]
>> https://stackoverflow.com/questions/2507337/how-to-determine-a-terminals-background-color
>>
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>