[Rd] Detect a terminated pipe

Kirill Müller kirill.mueller at ivt.baug.ethz.ch
Fri Mar 14 16:03:31 CET 2014

On 03/14/2014 03:54 PM, Simon Urbanek wrote:
> As far as R is concerned, the connection is open. In addition, pipes exist even without the process - you can close one end of a pipe and it will still exist (that’s what makes pipes useful, actually, because you can choose to close arbitrary combination of the R/W ends). Detecting that the other end of the pipe has closed is generally done by sending/receiving data to/from the end of interest - i.e. reading from a pipe that has closed the write end on the other side will yield 0 bytes read. Writing to a pipe that has closed the read end on the other side will yield SIGPIPE error (note that for text connections you have to call flush() to send the buffer):
>> >p=pipe("true","r")
>> >readLines(p)
> character(0)
>> >close(p)
>> >p=pipe("true","w")
>> >writeLines("", p)
>> >flush(p)
> Error in flush.connection(p) : ignoring SIGPIPE signal
>> >close(p)
Thanks for your reply. I tried this in an R console and received the 
error, just like you described. Unfortunately, the error is not thrown 
when trying the same in RStudio. Any ideas?



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