为什么用于终止端口进程的R system（）命令也会终止Ubuntu19.10RStudio会话？

用于终止端口进程的系统命令也会终止ubuntu 19.10上的Rstudio会话。在我的系统上，如果我执行以下操作，我会使RSTUDIO会话崩溃：

#IN RSTUDIO RUNNING LINE BY LINE
library(RSelenium)
rD1 <- rsDriver(browser="chrome",port=4567L, chromever = "79.0.3945.36")
system("kill -9 $(lsof -t -i:4567)")
Sys.sleep(1)

> sessionInfo()
R version 3.6.1 (2019-07-05)
Platform: x86_64-pc-linux-gnu (64-bit)
Running under: Ubuntu 19.10

Matrix products: default
BLAS:   /usr/lib/x86_64-linux-gnu/blas/libblas.so.3.8.0
LAPACK: /usr/lib/x86_64-linux-gnu/lapack/liblapack.so.3.8.0

locale:
 [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C               LC_TIME=en_US.UTF-8        LC_COLLATE=en_US.UTF-8    
 [5] LC_MONETARY=en_US.UTF-8    LC_MESSAGES=en_US.UTF-8    LC_PAPER=en_US.UTF-8       LC_NAME=C                 
 [9] LC_ADDRESS=C               LC_TELEPHONE=C             LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C       

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

loaded via a namespace (and not attached):
 [1] RSelenium_1.7.5  compiler_3.6.1   assertthat_0.2.1 tools_3.6.1      wdman_0.2.4      binman_0.1.1     Rcpp_1.0.3      
 [8] caTools_1.17.1.3 openssl_1.4.1    bitops_1.0-6     semver_0.2.0     XML_3.98-1.20    askpass_1.1