#       OpenPGP installation directory was successfully detected and added
  #       to the PATH -OR- detecting and adding it was not necessary because
  #       it already appeared to be available for use.
  #
  # <internal>
  proc probeForOpenPgpInstallation {} {
    global env
    variable openPgpInstalledDirectory
    variable openPgpInstalledFileName
    variable openPgpFileNameOnly
    variable openPgpInstalledDirectory

    if {[catch {openPgpMustBeInstalled}] == 0} then {
      return true
    }

    if {[isWindows]} then {
      if {[info exists env(ProgramFiles(x86))]} then {

      set directory $openPgpInstalledDirectory
    }

    if {![file isdirectory $directory]} then {
      return false
    }

    set fileName [file join $directory $openPgpInstalledFileName]
    set fileName [file join $directory $openPgpFileNameOnly]

    if {[file exists $fileName] && [file isfile $fileName]} then {
      return [addToPath $directory]
    }

    return false
  }

  #
  # NOTE: This procedure attempts to verify that a configured implementation
  #       of OpenPGP is installed locally.  There are no arguments.  Script
  #       errors are raised if any problems are found.  The return value is
  #       undefined.
  #
  # <public>
  proc openPgpMustBeInstalled {} {
    variable openPgpFileNameOnly
    variable openPgpInstalledCommand
    variable openPgpInstalledPattern

    set message {
      Cannot use OpenPGP: it does not appear to be installed.

      GNU Privacy Guard (GPG) may be downloaded from "https://www.gnupg.org/"
      and then installed.  Signed binaries for Windows may be available from
      "https://www.gpg4win.org/".

      Alternatively, it may be possible to install GNU Privacy Guard (GPG) via
      the package management subsystem included with your operating system.
    }

    if {[isEagle]} then {
      if {[catch {
        eval exec -success Success $openPgpInstalledCommand
        eval exec -success Success [subst $openPgpInstalledCommand]
      } result]} then {
        error $message
      }
    } else {
      if {[catch {
        eval exec $openPgpInstalledCommand
        eval exec [subst $openPgpInstalledCommand]
      } result]} then {
        error $message
      }
    }

    if {![info exists result] || \
        ![regexp -- $openPgpInstalledPattern $result]} then {

  #       OpenPGP signature is verified successfully.  A script error should
  #       not be raised by this procedure.  The fileName argument must be
  #       the fully qualified path and file name of the OpenPGP signature
  #       file to verify.
  #
  # <public>
  proc verifyOpenPgpSignature { fileName } {
    variable openPgpFileNameOnly
    variable openPgpVerifyCommand

    if {[isEagle]} then {
      set fileName [formatExecArgument $fileName]

      if {[catch {
        eval exec -success Success [subst $openPgpVerifyCommand]

  #       signature is created successfully.  A script error should not be
  #       raised by this procedure.  The fileName argument must be the fully
  #       qualified path and file name of the file to be signed.
  #
  # <public>
  proc createOpenPgpSignature { fileName } {
    global env
    variable openPgpFileNameOnly
    variable openPgpSignCommand

    if {[isEagle]} then {
      set fileName [formatExecArgument $fileName]

      if {[catch {
        eval exec -success Success [subst $openPgpSignCommand]

  #       the fully qualified path and file name of the OpenPGP key file
  #       to import.  This procedure is only intended to be used from the
  #       "pkgr_setup.eagle" tool script and may go away in later versions
  #       of this package.
  #
  # <internal>
  proc importOpenPgpKeyFile { fileName varName } {
    variable openPgpFileNameOnly
    variable openPgpImportCommand
    variable openPgpImportPattern

    if {[string length $varName] > 0} then {
      upvar 1 $varName result
    }

      if {[file exists $fileName] && [file isfile $fileName]} then {
        uplevel 1 [list source $fileName]
      }
    }
  }

  #
  # NOTE: This procedure sets up the default values for all configuration
  #       parameters used to interact with the OpenPGP implementation.
  #       There are no arguments.
  #
  proc setupRepositoryOpenPgpVars {} {
    #
    # NOTE: This is the name of the sub-directory containing the OpenPGP
    #       implementation.  It is platform-specific.  On Windows, this
    #       sub-directory is relative to the "Program Files" directory.
    #
    variable openPgpInstalledDirectory; # DEFAULT: [file join GNU GnuPG]

    if {![info exists openPgpInstalledDirectory]} then {
      if {[isWindows]} then {
        set openPgpInstalledDirectory [file join GNU GnuPG]
      } else {
        set openPgpInstalledDirectory [file join / usr bin]
      }
    }

    #
    # NOTE: This is the name of the executable file used to invoke the
    #       OpenPGP implementation, possibly without a file extension.
    #
    variable openPgpFileNameOnly; # DEFAULT: gpg2[.exe]

    if {![info exists openPgpFileNameOnly]} then {
      if {[isWindows]} then {
        set openPgpFileNameOnly gpg2.exe
      } else {
        set openPgpFileNameOnly gpg2
      }
    }

    #
    # NOTE: The command to use when attempting to import an OpenPGP key
    #       file.  This must be configured according to the implementation
    #       of OpenPGP in use.
    #
    variable openPgpImportCommand; # DEFAULT: gpg2 --import

    if {![info exists openPgpImportCommand]} then {
      set openPgpImportCommand \
          {{${openPgpFileNameOnly}} --import {${fileName}}}
    }

    #
    # NOTE: The regular expression pattern used when attempting to verify
    #       that OpenPGP successfully imported one or more keys.  This must
    #       be configured according to the implementation of OpenPGP in use.
    #
    variable openPgpImportPattern; # DEFAULT: ^gpg: Total number processed: 1$

    if {![info exists openPgpImportPattern]} then {
      set openPgpImportPattern {^gpg: Total number processed: 1$}
    }

    #
    # NOTE: The command to use when attempting to verify that OpenPGP is
    #       installed locally.  This must be configured according to the
    #       implementation of OpenPGP in use.
    #
    variable openPgpInstalledCommand; # DEFAULT: gpg2 --version

    if {![info exists openPgpInstalledCommand]} then {
      set openPgpInstalledCommand \
          {{${openPgpFileNameOnly}} --version}
    }

    #
    # NOTE: The regular expression pattern used when attempting to verify
    #       that OpenPGP is installed locally.  This must be configured
    #       according to the implementation of OpenPGP in use.
    #
    variable openPgpInstalledPattern; # DEFAULT: ^gpg \(GnuPG\) 2\.[012]\.

    if {![info exists openPgpInstalledPattern]} then {
      set openPgpInstalledPattern {^gpg \(GnuPG\) 2\.[012]\.}
    }

    #
    # NOTE: The command to use when verifying OpenPGP signatures for the
    #       downloaded package scripts.  This must be configured according
    #       to the implementation of OpenPGP in use.
    #
    variable openPgpVerifyCommand; # DEFAULT: gpg2 --verify {${fileName}}

    if {![info exists openPgpVerifyCommand]} then {
      set openPgpVerifyCommand \
          {{${openPgpFileNameOnly}} --verify {${fileName}}}
    }

    #
    # NOTE: The command to use when creating OpenPGP signatures for the
    #       downloaded package scripts.  This must be configured according
    #       to the implementation of OpenPGP in use.
    #
    variable openPgpSignCommand; # DEFAULT: gpg2 --detach-sign ...

    if {![info exists openPgpSignCommand]} then {
      set openPgpSignCommand ""

      append openPgpSignCommand \
          {{${openPgpFileNameOnly}} --detach-sign --armor}

      append openPgpSignCommand \
          { --passphrase-file [formatExecArgument [getOpenPgpPassphraseFile]]}

      append openPgpSignCommand { --batch --yes {${fileName}}}
    }
  }

  #
  # NOTE: This procedure sets up the default values for all configuration
  #       parameters used by the package repository client.  There are no
  #       arguments.
  #
  proc setupPackageUnknownVars {} {
    #

          [llength [package versions Garuda]] > 0} then {
        set autoRequireGaruda true
      } else {
        set autoRequireGaruda false
      }
    }

    #
    # NOTE: This is the name of the sub-directory containing the OpenPGP
    #       implementation.  It is platform-specific.  On Windows, this
    #       sub-directory is relative to the "Program Files" directory.
    #
    variable openPgpInstalledDirectory; # DEFAULT: [file join GNU GnuPG]

    if {![info exists openPgpInstalledDirectory]} then {
      if {[isWindows]} then {
        set openPgpInstalledDirectory [file join GNU GnuPG]
      } else {
        set openPgpInstalledDirectory [file join / usr bin]
      }
    }

    #
    # NOTE: This is the name of the executable file used to invoke the
    #       OpenPGP implementation, without an extension.
    #
    variable openPgpInstalledFileName; # DEFAULT: gpg2

    if {![info exists openPgpInstalledFileName]} then {
      if {[isWindows]} then {
        set openPgpInstalledFileName gpg2.exe
      } else {
        set openPgpInstalledFileName gpg2
      }
    }

    #
    # NOTE: The command to use when attempting to import an OpenPGP key
    #       file.  This must be configured according to the implementation
    #       of OpenPGP in use.
    #
    variable openPgpImportCommand; # DEFAULT: gpg2 --import

    if {![info exists openPgpImportCommand]} then {
      set openPgpImportCommand {gpg2 --import {${fileName}}}
    }

    #
    # NOTE: The regular expression pattern used when attempting to verify
    #       that OpenPGP successfully imported one or more keys.  This must
    #       be configured according to the implementation of OpenPGP in use.
    #
    variable openPgpImportPattern; # DEFAULT: ^gpg: Total number processed: 1$

    if {![info exists openPgpImportPattern]} then {
      set openPgpImportPattern {^gpg: Total number processed: 1$}
    }

    #
    # NOTE: The command to use when attempting to verify that OpenPGP is
    #       installed locally.  This must be configured according to the
    #       implementation of OpenPGP in use.
    #
    variable openPgpInstalledCommand; # DEFAULT: gpg2 --version

    if {![info exists openPgpInstalledCommand]} then {
      set openPgpInstalledCommand {gpg2 --version}
    }

    #
    # NOTE: The regular expression pattern used when attempting to verify
    #       that OpenPGP is installed locally.  This must be configured
    #       according to the implementation of OpenPGP in use.
    #
    variable openPgpInstalledPattern; # DEFAULT: ^gpg \(GnuPG\) 2\.[01]\.

    if {![info exists openPgpInstalledPattern]} then {
      set openPgpInstalledPattern {^gpg \(GnuPG\) 2\.[01]\.}
    }

    #
    # NOTE: The command to use when verifying OpenPGP signatures for the
    #       downloaded package scripts.  This must be configured according
    #       to the implementation of OpenPGP in use.
    #
    variable openPgpVerifyCommand; # DEFAULT: gpg2 --verify {${fileName}}

    if {![info exists openPgpVerifyCommand]} then {
      set openPgpVerifyCommand {gpg2 --verify {${fileName}}}
    }

    #
    # NOTE: The command to use when creating OpenPGP signatures for the
    #       downloaded package scripts.  This must be configured according
    #       to the implementation of OpenPGP in use.
    #
    variable openPgpSignCommand; # DEFAULT: gpg2 --detach-sign ...

    if {![info exists openPgpSignCommand]} then {
      set openPgpSignCommand ""

      append openPgpSignCommand {gpg2 --detach-sign --armor}

      append openPgpSignCommand \
          { --passphrase-file [formatExecArgument [getOpenPgpPassphraseFile]]}

      append openPgpSignCommand { --batch --yes {${fileName}}}
    }

    #
    # NOTE: The command to use when creating Harpy signatures for downloaded
    #       package scripts.
    #
    variable harpySignCommand; # DEFAULT: {${shellFileName}} -file ...

    if {![info exists harpySignCommand]} then {

  #
  # NOTE: Setup the server and URI variables, in this namespace, that are
  #       used by this script.
  #
  setupRepositoryServerVars false
  setupRepositoryUriVars false

  #
  # NOTE: Setup the OpenPGP implementation related variables, in this
  #       namespace, that are used by this script.
  #
  setupRepositoryOpenPgpVars

  #
  # NOTE: Setup the variables, within this namespace, used by this script.
  #
  setupPackageUnknownVars

  #
  # NOTE: Setup for our [package unknown] handler, which may involve a few