Hi,

on my R-3.0.2 windows (32bits) no error is thrown occurs when calling a
shell command with intern=TRUE, mustWork=TRUE. Is this a intended/known
behaviour?

>From the source of base::shell it is clear that mustWork is only used when
intern=FALSE. This is not that clear from the help page:

"
Arguments
mustWork a logical; if TRUE failure to run the command will give an R
error, if FALSE a warning and if NA, no R message.

Value
If intern = TRUE, a character vector giving the output of the command, one
line per character string, or an error message if the command could not be
run.
"


Thank you.

Bests,
Renaud

## Example ###

# no error as expected
shell('notacommand')
shell('notacommand', intern=TRUE)
# error as expected
shell('notacommand', mustWork = TRUE)
# I am expecting to get an error here as well, but none is thrown
shell('notacommand', intern = TRUE, mustWork = TRUE)

sessionInfo()

### Output ###

> # no error as expected
> shell('notacommand')
'notacommand' is not recognized as an internal or external command,
operable program or batch file.
Warning messages:
1: running command 'C:\Windows\system32\cmd.exe /c notacommand' had status
1
2: In shell("notacommand") :
  'notacommand' execution failed with error code 1
> shell('notacommand', intern=TRUE)
[1] "'notacommand' is not recognized as an internal or external command,"
[2] "operable program or batch file."
attr(,"status")
[1] 1
Warning message:
running command 'C:\Windows\system32\cmd.exe /c notacommand' had status 1
> # error as expected
> shell('notacommand', mustWork = TRUE)
'notacommand' is not recognized as an internal or external command,
operable program or batch file.
Error in shell("notacommand", mustWork = TRUE) :
  'notacommand' execution failed with error code 1
In addition: Warning message:
running command 'C:\Windows\system32\cmd.exe /c notacommand' had status 1
> # I am expecting to get an error here as well, but none is thrown
> shell('notacommand', intern = TRUE, mustWork = TRUE)
[1] "'notacommand' is not recognized as an internal or external command,"
[2] "operable program or batch file."
attr(,"status")
[1] 1
Warning message:
running command 'C:\Windows\system32\cmd.exe /c notacommand' had status 1
>
> sessionInfo()
R version 3.0.2 (2013-09-25)
Platform: i386-w64-mingw32/i386 (32-bit)

locale:
[1] LC_COLLATE=English_United States.1252
[2] LC_CTYPE=English_United States.1252
[3] LC_MONETARY=English_United States.1252
[4] LC_NUMERIC=C
[5] LC_TIME=English_United States.1252

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

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