`fread` with filenames containing spaces returns non-instructive warning and not error

[richard-davey-arcadisgen]

# Minimal reproducible example; please be sure to set verbose=TRUE where possible!

Where a file does not exist and the filename does not contain spaces, the datatable::fread() function errors correctly.

fread(file.path("data_raw", "foobar.csv"))

Error in fread(file.path("data_raw", "foobar.csv")) :
File 'data_raw/foobar.csv' does not exist or is non-readable. getwd()=='C:/projects/'

However, where a file does not exist and the filename does contain spaces, the datatable::fread() function does not error at all; it warns incorrectly.

fread(file.path("data_raw", "foo bar.csv"))

'data_raw' is not recognized as an internal or external command,
operable program or batch file.
Null data.table (0 rows and 0 cols)

This is problematic as any Rmarkdown document proceeds beyond the warning and errors downstream when relying on the null data.table. My expectation would be that an error - not a warning - would be raised.

# Output of sessionInfo()

R version 4.4.1 (2024-06-14 ucrt)
Platform: x86_64-w64-mingw32/x64
Running under: Windows 11 x64 (build 26200)

Matrix products: default


locale:
[1] LC_COLLATE=English_United Kingdom.utf8  LC_CTYPE=English_United Kingdom.utf8    LC_MONETARY=English_United Kingdom.utf8 LC_NUMERIC=C                           
[5] LC_TIME=English_United Kingdom.utf8    

time zone: Europe/London
tzcode source: internal

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

other attached packages:
 [1] RANN_2.6.2         waterfalls_1.1.4   yardstick_1.4.0    caret_7.0-1        lattice_0.22-6     vip_0.4.6          tune_2.1.0         workflows_1.3.0   
 [9] workflowsets_1.1.1 parsnip_1.6.0      themis_1.0.3       recipes_1.3.3      rsample_1.3.2      ggplot2_4.0.0      tidyr_1.3.1        dplyr_1.1.4       
[17] sf_1.0-21          data.table_1.17.8  knitr_1.50        

loaded via a namespace (and not attached):
 [1] tidyselect_1.2.1     timeDate_4052.112    farver_2.1.2         S7_0.2.0             fastmap_1.2.0        pROC_1.19.0.1        digest_0.6.37       
 [8] rpart_4.1.23         timechange_0.3.0     lifecycle_1.0.4      survival_3.6-4       magrittr_2.0.4       compiler_4.4.1       rlang_1.1.6         
[15] tools_4.4.1          yaml_2.3.10          bit_4.6.0            classInt_0.4-11      plyr_1.8.9           DiceDesign_1.10      RColorBrewer_1.1-3  
[22] KernSmooth_2.23-24   withr_3.0.2          purrr_1.2.0          stats4_4.4.1         nnet_7.3-19          grid_4.4.1           e1071_1.7-16        
[29] future_1.68.0        iterators_1.0.14     globals_0.18.0       scales_1.4.0         MASS_7.3-60.2        cli_3.6.5            crayon_1.5.3        
[36] rmarkdown_2.30       generics_0.1.4       rstudioapi_0.17.1    future.apply_1.20.2  tzdb_0.5.0           reshape2_1.4.4       DBI_1.2.3           
[43] proxy_0.4-27         stringr_1.5.2        splines_4.4.1        dials_1.4.4          parallel_4.4.1       vctrs_0.6.5          hardhat_1.4.2       
[50] Matrix_1.7-0         hms_1.1.4            bit64_4.6.0-1        listenv_0.10.0       foreach_1.5.2        gower_1.0.2          units_1.0-0         
[57] glue_1.8.0           parallelly_1.45.1    codetools_0.2-20     stringi_1.8.7        lubridate_1.9.4      gtable_0.3.6         ROSE_0.0-4          
[64] tibble_3.3.0         furrr_0.3.1          pillar_1.11.1        htmltools_0.5.8.1    ipred_0.9-15         lava_1.9.2           R6_2.6.1            
[71] vroom_1.6.6          evaluate_1.0.5       readr_2.1.5          renv_0.14.0          class_7.3-22         Rcpp_1.1.2           nlme_3.1-164        
[78] prodlim_2026.03.11   xfun_0.53            ModelMetrics_1.2.2.2 pkgconfig_2.0.3     

[aitap]

Thank you for the report! fread(file = ...) will always fail for non-existent files. fread(input = ...) is magic and tries to guess that the space-containing argument that doesn't correspond to a file must be an external command. fread(cmd = ...) didn't handle failing external commands until #7097, but 1.17.8 is too old to have that fix.