Running a shell command

General
1

I’m trying to run a command line tool from within a Shell in a desktop app. I’m on a Mac.

The tool is definitely installed on my Mac in my PATH. The tool is called rtl_433.

In the macOS Terminal if I run:

which rtl_433

I get:

/opt/homebrew/bin/rtl_433

If I put this code in the Opening event of my app:

Var sh As New Shell
sh.ExecuteMode = Shell.ExecuteModes.Synchronous
sh.Execute("which ls")
Var result As String = sh.Result ' bin/ls

sh.Execute("which rtl_433")
result = sh.Result ' Empty. Shell returns error 1
Break

The Shell can’t find rtl_433. The execute command is working though because it finds the ls tool which is bundled with macOS.

Does anyone have any code that will run a CLI from a Shell? I’m guessing this has something to do with the incorrect PATH in Xojo’s Shell class but I’m not sure how to address it.

1 Like
2

Call the utility with the complete path.

sh.Execute "/path/to/cli"
3

And just like that, the problem is solved. Thanks.

Out of interest, any idea why you have to use the full path?

4

You have to use the full path because the Xojo shell is not the Terminal and therefore doesn’t know the new CLI.

2 Likes
5

When you log into your account, it gets a lot of information from the environment. When you run a shell script, or run a shell from xojo, you don’t have all that information. Both shell scripts and xojo shells have to be more explicit.

2 Likes
6

in the terminal, if you run the ‘env’ command you will see the PATH variable. On my machine it’s this long mess:

PATH=/opt/local/bin:/opt/local/sbin:/opt/local/bin:/opt/local/sbin:/usr/local/bin:/System/Cryptexes/App/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Library/Apple/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/local/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/bin:/var/run/com.apple.security.cryptexd/codex.system/bootstrap/usr/appleinternal/bin

(apparently the Cryptexes and codex stuff is new in Ventura, ugh)

In Xojo if you run this code:

dim sh as new shell
sh.Execute("env")
MessageBox sh.Result

the PATH is quite different:

PATH=/usr/bin:/bin:/usr/sbin:/sbin

3 Likes
7

FYI, you can use something like this on Mac or Linux to get the path to the utility you want:

Private Function FindCliApp(cli As String) As FolderItem
  dim f as FolderItem
  
  #if TargetMacOS or TargetLinux then
    dim sh as new shell
    sh.Execute "/bin/bash -lc " + ShellQuote("which " + cli.Trim)
    if sh.ErrorCode = 0 then
      dim path as string = sh.Result
      path = ReplaceLineEndings(path, EndOfLine).Trim
      path = path.NthField(EndOfLine, path.CountFields(EndOfLine))
      f = new FolderItem(path, FolderItem.PathTypeNative)
    end if
  #endif
  
  return f
  
End Function

Private Function ShellQuote(s As String) As String
  s = s.ReplaceAll("'", "'\''")
  s = "'" + s + "'"
  return s
  
End Function
4 Likes
8

I know this is an old thread. Still, Kem, thank you for this. It was very useful. It turned out that I was already close. However, I found that, to get it to work on my Sequoia (M1) system, I had to change the shell backend to zsh. I keep bash for pre-Catalina.

2 Likes