I cannot redirect the I/O streams from r_bg().

[wlandau]

# The error message is cryptic.
callr::r_bg(func = function() 1 + "A", stdout = "~/out.txt", stderr = "~/err.txt")
#> Error in process_initialize(self, private, command, args, stdout, stderr, : callr error
# No traceback or warnings are available to the master process.
traceback()
#> No traceback available
warnings()
#> NULL
# Neither I/O stream made it to a text file.
any(c("out.txt", "err.txt") %in% list.files("~"))
#> [1] FALSE
# Using development callr: 3d398568995e5769eb9cab844ca735662e009485
sessionInfo()
#> R version 3.4.3 (2017-11-30)
#> Platform: x86_64-pc-linux-gnu (64-bit)
#> Running under: KDE neon User Edition 5.12
#> 
#> Matrix products: default
#> BLAS: /usr/lib/libblas/libblas.so.3.6.0
#> LAPACK: /usr/lib/lapack/liblapack.so.3.6.0
#> 
#> locale:
#>  [1] LC_CTYPE=en_US.UTF-8       LC_NUMERIC=C              
#>  [3] 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   
#>  [7] LC_PAPER=en_US.UTF-8       LC_NAME=C                 
#>  [9] LC_ADDRESS=C               LC_TELEPHONE=C            
#> [11] 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] Rcpp_0.12.15     crayon_1.3.4     digest_0.6.15    rprojroot_1.3-2 
#>  [5] assertthat_0.2.0 R6_2.2.2         backports_1.1.2  formatR_1.5     
#>  [9] magrittr_1.5     evaluate_0.10.1  debugme_1.1.0    stringi_1.1.6   
#> [13] callr_2.0.2.9001 rmarkdown_1.8    tools_3.4.3      stringr_1.3.0   
#> [17] yaml_2.1.16      compiler_3.4.3   htmltools_0.3.6  knitr_1.20

[gaborcsardi]

~ is not expanded, you need to use path.expand() manually.

[wlandau]

Thanks @gaborcsardi, it worked.

callr::r_bg(
  func = function() 1 + "A",
  stdout = path.expand("~/out.txt"),
  stderr = path.expand("~/err.txt")
)