Hi Jen, This was already resolved for R 3.5.1 by just disabling buffering on terminal file connections like stdin.
Sounds like you might want to be running a web service or something instead though. Michael On Tue, Jun 12, 2018 at 4:46 PM, Jennifer Lyon <jennifer.s.l...@gmail.com> wrote: > Hi: > > I have also just stumbled into this bug. Unfortunately, I can not > change the data my program receives from stdin. My code runs in a > larger system and stdin is sent to a Docker container running my R > code. The protocol is I read a line, readLines("stdin", n=1), do some > actions, send output on stdout, and wait for the next set of data. I > don't have control over this protocol, so I can't use the ^D > workaround. > > I am open for other workaround suggestions. The single line is > actually JSON and can be quite large. If there isn't something else > cleaner, I am going to try readChar() in a while loop looking for \n > but I'm guessing that would likely be too slow. I am open to other > workaround solutions. For the moment I have reverted back to R 3.4.4. > > Thanks for any suggestions. > > Jen. > > >>> >>>>> Martin Maechler >>> >>>>> on Mon, 28 May 2018 10:28:01 +0200 writes: >>> >>> >>>>> Ralf Stubner >>> >>>>> on Fri, 25 May 2018 19:18:58 +0200 writes: >>> >>> >> Dear all, I would like to draw you attention to this >>> >> question on SO: >>> >> > https://stackoverflow.com/questions/50372043/readlines-function-with-new-version-of-r >>> >>> >>> >> Based on the OP's code I used the script >>> >>> >> ####################################### >>> >> create_matrix <- function() { >>> >> cat("Write the numbers of vertices: ") >>> >> user_input <- readLines("stdin", n=1) >>> >> user_input <- as.numeric(user_input) >>> >> print(user_input) >>> >> } >>> >> create_matrix() >>> >> ####################################### >>> >>> >> and called it with "R -f <filename>" from the command line. >>> >>> >> With 'R version 3.4.4 (2018-03-15) -- "Someone to Lean On"' the > script >>> >> prints the inputed number as expected. With both 'R version 3.5.0 >>> >> (2018-04-23) -- "Joy in Playing"' and 'R Under development > (unstable) >>> >> (2018-05-19 r74746) -- "Unsuffered Consequences"' the script does > not >>> >> continue after inputing a number. >>> >>> > I can confirm. >>> > It "works" if you additionally (the [Enter], i.e., EOL) you also >>> > "send" an EOF -- in Unix alikes via <Ctrl>-D >>> >>> > The same happens if you use 'Rscript <filename>' >>> >>> > I'm not the expert here, but am close to sure that we (R core) >>> > did not intend this change, when fixing other somewhat subtle >>> > bugs in Rscript / 'R -f' >>> >>> > Martin Maechler >>> >>> The same behavior in regular R , no need for a script etc. >>> >>> > str(readLines("stdin", n=1)) >>> >>> then in addition to the input you need to "give" an EOF (Ctrl D) in R >>= 3.5.0 >>> >>> Interestingly, everything works fine if you use stdin() instead >>> of "stdin" : >>> >>> > rr <- readLines(stdin(), n=1) >>> foo >>> > rr >>> [1] "foo" >>> > >>> ---------- >>> >>> So, for now use stdin() which is much clearer than the string >>> "stdin" anyway >>> >>> Martin Maechler > > [[alternative HTML version deleted]] > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel