编辑Windows环境变量

我已阅读以下几个问题：

在R中为pdflatex设置miktex的路径

如何在R中设置用于编织的乳胶路径？

https://tex.stackexchange.com/questions/267299/how-to-fix-the-sorry-but-c-miktex-pdftex-exe-did-not-succeed-error https://tex.stackexchange.com / questions / 429706 / rstudio-not-detecting-miktex https://tex.stackexchange.com/questions/231595/rstudio-cant-find-pdflatex-on-windows-7

上面的列表并没有穷尽我尝试过的所有内容，还包括重新安装RStudio，R和MikTex。

然后我以为我可以编辑路径以删除R不断调用的MikTeX 1.9，但不知道该怎么做。

我发现此函数表明我已经为MikTex设置了正确的路径，但是R继续调用MikTeX 1.9：

Sys.which2 <- function(cmd) {
  stopifnot(length(cmd) == 1)
  if (.Platform$OS.type == "windows") {
    suppressWarnings({
      pathname <- shell(sprintf("where %s 2> NUL", cmd), intern=TRUE)[1]
    })
    if (!is.na(pathname)) return(setNames(pathname, cmd))
  }
  Sys.which(cmd)
}

Sys.which和之间的输出不同Sys.which2：

Sys.which2("pdflatex")
                                                       pdflatex 
"C:\\Program Files\\MiKTeX 2.9\\miktex\\bin\\x64\\pdflatex.exe" 

 Sys.which("pdflatex")
                                                  pdflatex 
"C:\\PROGRA~1\\MIKTEX~1.9\\miktex\\bin\\x64\\pdflatex.exe" 

我怎样才能最好地解决这个问题？

我的想法是以某种方式找到R在哪里找到此MikTeX 1.9并替换它，但我无法在系统上找到它，也不十分了解Sys.which幕后行为。

编辑

尝试确定1.9的位置是：

stringr::str_detect(unlist(strsplit(Sys.getenv("PATH"),";")),"latex")
 [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
[13] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
[25] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
[37] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE

输出sys.getenv("PATH"：

“ C：/ Program Files / MiKTeX 2.9 / miktex / bin / x64：C：\ Program Files \ R \ R-3.6.2 \ bin \ x64; C：\ Program Files（x86）\ Common Files \ Oracle \ Java \ javapath; C：\ ProgramData \ Oracle \ Java \ javapath; C：\ Program Files \ copasi.org \ COPASI 4.22.170 \ bin; C：\ Program Files（x86）\ Intel \ TXE Components \ iCLS \; C：\程序文件\英特尔\ TXE组件\ iCLS \; C：\ WINDOWS \ system32; C：\ WINDOWS; C：\ WINDOWS \ System32 \ Wbem; C：\ WINDOWS \ System32 \ WindowsPowerShell \ v1.0 \; C：\ Users \ Administrator \ AppData \ Local \ Microsoft \ WindowsApps; C：\ Recovery \ OEM \ Backup \; C：\ Program Files \ Intel \ TXE Components \ DAL \; C：\ Program Files（x86）\ Intel \ TXE Components \ DAL \; C：\ Program Files \ Intel \ TXE Components \ IPT \; C：\ Program Files（x86）\ Intel \ TXE Components \ IPT \; C：\ Program Files \ Intel \ WiFi \ bin \; C：\ Program Files \ Common Files \ Intel \ WirelessCommon \; C：\ WINDOWS \ system32; C：\ WINDOWS; C：\ WINDOWS \ System32 \ Wbem; C：\ WINDOWS \ System32 \ WindowsPowerShell \ v1.0 \; C：\ WINDOWS \ System32 \ OpenSSH \; E：\ MATLAB \ runtime \ win64; E：\ MATLAB \ bin; C：\ Program Files \ Git \ cmd; C： \ Program Files \ Microsoft SQL Server \ Client SDK \ ODBC \ 130 \ Tools \ Binn \; C：\ Program Files（x86）\ Microsoft SQL Server \ 140 \ Tools \ Binn \; C：\ Program Files \ Microsoft SQL Server \ 140 \ Tools \ Binn \; C：\ Program Files \ Microsoft SQL Server \ 140 \ DTS \ Binn \; C：\ ProgramData \ chocolatey \ bin; C：\ Program Files \ MiKTeX 2.9 \ miktex \ bin \ x64 \; C ：\ Users \我的名字\ AppData \ Local \ Programs \ Python \ Python38 \ Scripts \; C：\ Users \我的名字\ AppData \ Local \ Programs \ Python \ Python38 \; C：\ Users \我的名字\ AppData \ Local \ Programs \ Python \ Python36 \ Scripts \; C：\ Users \ my name \ AppData \ Local \ Programs \ Python \ Python36 \; C：\ Users \ my name \ Desktop \ wget-1.20.3-win64; C：\用户\我的名字\ AppData \ Local \ Programs \ Python \ Python37 \ Scripts \; C：\用户\我的名字\ AppData \ Local \ Programs \ Python \ Python37 \; C：\ Users \我的名字\ AppData \ Local \ Microsoft \ WindowsApps; C：\ Users \我的名字\ AppData \ Local \ Programs \ Python \ Python37-32; E：\ jdk-12_windows-x64_bin; C：\ Users \我的名字\ AppData \ Local \ Microsoft \ WindowsApps; C：\ Users \ my name \ Desktop \ adb +-+ platform + tools + v28.0.1“