Using ExecuteScriptText to get a list of all environment variables and their values

//**
// Using ExecuteScriptText, gets the environment variables.
// Variables are returned as a carriage-return-separated
// string.
//
// Usage examples:
//  print GetEnvironmentVariables()     // Prints all variables to Igor's command history
//  String sys_path = StringByKey("PATH", GetEnvironmentVariables(), "=", "\r")
//*
Function/S GetEnvironmentVariables()

    String envInfoString = ""

   
    // This has to be done differently depending on the operating system.
    String platform = IgorInfo(2)
    String errorMessage
    StrSwitch (platform)
        Case "Windows":
            try
                // Do some setup.
                String tmpDir = SpecialDirPath("Temporary", 0, 0, 0)
                AbortOnValue (numtype(strlen(tmpDir)) != 0 || !(strlen(tmpDir) > 0)), 1
   
               
                // Make sure that the directory we just got is, in fact, a directory.
                GetFileFolderInfo/Q tmpDir
                AbortOnValue (V_Flag >= 0 && !V_isFolder), 3
               
                // Set an Igor symbolic path to the temporary directory.
                String tmpDirectoryPath = UniqueName("tmpPath", 12, 0)
                NewPath/Q $(tmpDirectoryPath), tmpDir
                AbortOnValue (V_flag), 5        // Setting of the new path failed.
               
                // Write a temporary batch file to the temporary directory that will
                // call the "set" command from the command shell and save the
                // output of the command to a temporary file.
                String tempBatFileName, tempResultsFileName
                String tempBatFileFullPath, tempResultsFileFullPath
                Variable tempBatFileRefNum, tempResultsFileRefNum
               
                sprintf tempBatFileName, "IgorGetEnvironmentVars_%.4u.bat", abs(trunc(StopMsTimer(-2)))
                Open/P=$(tmpDirectoryPath)/T=".bat"/Z=1 tempBatFileRefNum as tempBatFileName
                AbortOnValue (V_flag != 0), 7
   
                // Add a path separator character to the end of the path, if necessary, and add on the file name.
                tempBatFileFullPath = ParseFilePath(2, tmpDir, ":", 0, 0) + tempBatFileName
               
                // Convert the path into a windows path that uses "\" as the path separator.
                tempBatFileFullPath = ParseFilePath(5, tempBatFileFullPath, "\\", 0, 0)
   
                sprintf tempResultsFileName, "IgorGetEnvironmentVars_%.4u.txt", abs(trunc(StopMsTimer(-2)))        
   
                // Add a path separator character to the end of the path, if necessary, and add on the file name.
                tempResultsFileFullPath = ParseFilePath(2, tmpDir, ":", 0, 0) + tempResultsFileName
               
                // Convert the path into a windows path that uses "\" as the path separator.
                tempResultsFileFullPath = ParseFilePath(5, tempResultsFileFullPath, "\\", 0, 0)
   
                fprintf tempBatFileRefNum, "set > \"%s\"\r\n", tempResultsFileFullPath
                Close tempBatFileRefNum
               
                // Call the batch file we just created.  Timeout after 2 seconds if this doesn't succeed.
                String scriptText
                sprintf scriptText, "cmd.exe /C \"%s\"", tempBatFileFullPath
                ExecuteScriptText/W=2/Z scriptText
               
                // Check for an error.
                AbortOnValue (V_flag != 0), 9
               
                // Check that the temporary results file exists.
                GetFileFolderInfo/Z=1/Q/P=$(tmpDirectoryPath) tempResultsFileName
                AbortOnValue (V_flag != 0 || !(V_isFile)), 10
               
                // Get the results from the temporary file created by the batch file.
                Open/P=$(tmpDirectoryPath)/R/Z=1 tempResultsFileRefNum as tempResultsFileName
                AbortOnValue (V_flag != 0), 12

                String buffer
                do
                    FReadLine tempResultsFileRefNum, buffer
                    if (strlen(buffer) <= 0)
                        break
                    else
                        envInfoString += buffer
                    endif
                while (1)  
                Close tempResultsFileRefNum
               
                // Delete the temporary batch file and temporary results file.
                DeleteFile/P=$(tmpDirectoryPath)/Z=1 tempBatFileName
                DeleteFile/P=$(tmpDirectoryPath)/Z=1 tempResultsFileName
                // If we get an error here we don't really care.  We've already got
                // the goods, so just run.
                break
            catch
                // Error handling
                Switch (V_abortCode)
                    Case 1:
                        errorMessage = "Could not locate the operating system's temporary directory, so can't get environment variables."
                        break
                    Case 3:
                        errorMessage = "Could not locate the operating system's temporary directory, so can't get environment variables."
                        break
                    Case 5:
                        errorMessage = "Igor was unable to create a symbolic path to the temporary file directory."
                        break
                    Case 7:
                        errorMessage = "Igor was unable to create a batch file in the temporary directory."
                        break
                    Case 9:
                        errorMessage = "Igor was unable to execute the batch file to read the environment variables."
                        break
                    Case 10:
                        errorMessage = "Igor was unable to locate or read the temporary file containing environment variables."
                        break
                    Case 12:
                        errorMessage = "Igor was unable to open the temporary file containing environment variables."
                        break
                    default:
                        errorMessage = "An unspecified error occurred while trying to read the environment variables."                     
                EndSwitch
                print errorMessage
                KillPath/Z $(tmpDirectoryPath)
                return ""
           
            endtry
           
        Case "Macintosh":
            // This is a lot easier on the Macintosh because we can just use AppleScript.
            try
                String appleScriptCommand = "do shell script \"env\""
                ExecuteScriptText/Z appleScriptCommand
                AbortOnValue V_flag, 1
               
                envInfoString = S_Value
            catch
                errorMessage = "Could not execute AppleScript command."
                print errorMessage
                return ""              
            endtry
            break
    EndSwitch
    return envInfoString
End