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r - 在 Linux 中查找软件包的二进制文件

问题描述

我正在整理一个包，但是我似乎没有找到让包在系统中找到二进制文件的方法，请注意以下代码：

    find_nim <- function(message=TRUE) {
  nimexe <- ""
  if (.Platform$OS.type == "unix") {
      nimexe <- try(system2("which", "nim", stdout=TRUE))
      if (message) message("Nim found at ", nimexe)
  } else {
    message("Unrecognized operating system.")
  }
#  if (nimexe=="") message("nim executable not found.\n Specify the location of your nim executable.")
  return(nimexe)
}

这将在安装包时返回：

Warning in system2("which", "nim", stdout = TRUE) :
  running command ''which' nim' had status 1
Nim found at 
Error: package or namespace load failed for ‘nimrmarkdown’:
 .onAttach failed in attachNamespace() for 'nimrmarkdown', details:
  call: if (nimexe != "") {
  error: argument is of length zero

相同的代码在 R 中本地工作。

标签： r

解决方案

R 本身有Sys.which()你可以使用：

R> Sys.which("emacs")
           emacs 
"/usr/bin/emacs" 
R> Sys.which("does_not_exist")
does_not_exist 
            "" 
R>

编写 R 扩展手册也提到了它：

 Usage of external commands should always be conditional on a test
 for existence (perhaps using 'Sys.which'), as well as declared in
 the 'SystemRequirements' field.

和

 example in some locales.  (Use e.g. 'capabilities()' or
 'nzchar(Sys.which("someprogram"))' to test for features needed in
 the examples wherever possible, and you can also use 'try()' or

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