proc $procName $procArgs [appendArgs $procPreBody $procBody]

      return [uplevel 1 [list $procName] $args]
    }
  }

  #
  # NOTE: This procedure returns a string argument value, which may contain
  #       spaces, for use with the [exec] command.  The value argument is
  #       the string value to format as an [exec] argument.
  #
  proc formatExecArgument { value } {
    if {[isEagle]} then {
      return [appendArgs \" $value \"]
    } else {
      return $value
    }
  }

  #
  # NOTE: This procedure returns a formatted, possibly version-specific,
  #       package name, for use in logging.  The package argument is the
  #       name of the package.  The version argument is the version of the
  #       package.
  #
  proc formatPackageName { package version } {

  #       file to verify.
  #
  # <public>
  proc verifyOpenPgpSignature { fileName } {
    variable openPgpVerifyCommand

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

      if {[catch {
        eval exec -success Success [subst $openPgpVerifyCommand]
      }] == 0} then {
        return true
      }
    } else {
      if {[catch {
        eval exec [subst $openPgpVerifyCommand] 2>@1
      }] == 0} then {
        return true
      }
    }

    return false
  }

  #
  # NOTE: This procedure returns the name of the file containing the OpenPGP
  #       passphrase.  This procedure is only used when creating an OpenPGP
  #       signature.  There are no arguments.
  #
  proc getOpenPgpPassphraseFile {} {
    global env

    if {[info exists env(GPG_PASSPHRASE_FILE)]} then {
      set fileName [file normalize $env(GPG_PASSPHRASE_FILE)]

      if {[file exists $fileName]} then {
        return $fileName
      } else {
        error "cannot sign with OpenPGP: passphrase file does not exist"
      }
    } else {
      error "cannot sign with OpenPGP: passphrase file is not configured"
    }
  }

  #
  # NOTE: This procedure attempts to create an OpenPGP signature for the
  #       specified (named) file.  Non-zero is only returned if the OpenPGP
  #       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 openPgpSignCommand

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

      if {[catch {
        eval exec -success Success [subst $openPgpSignCommand]
      }] == 0} then {
        return true
      }
    } else {
      if {[catch {
        eval exec [subst $openPgpSignCommand] 2>@1
      }] == 0} then {
        return true
      }
    }

    return false
  }

  #
  # NOTE: This procedure attempts to import the OpenPGP keys contained in
  #       the specified (named) file.  Non-zero is only returned if the

    variable openPgpImportPattern

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

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

      if {[catch {
        eval exec -nocarriagereturns -stdout output -stderr error \
            [subst $openPgpImportCommand]
      } result] == 0} then {
        set result [appendArgs $output $error]
      } else {

    #       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: Verify that the package script matches the current language
    #       when called from the [package unknown] handler?
    #
    variable strictUnknownLanguage; # DEFAULT: true