use bsdtar on linux (#1234)

kindlecomicconverter/KCC_gui.py

@@ -42,7 +42,7 @@ from raven import Client
 from tempfile import gettempdir
 
 from .shared import HTMLStripper, sanitizeTrace, walkLevel, subprocess_run
-from .comicarchive import SEVENZIP, available_archive_tools
+from .comicarchive import SEVENZIP, TAR, available_archive_tools
 from . import __version__
 from . import comic2ebook
 from . import metadata
@@ -1358,7 +1358,7 @@ class KCCGUI(KCC_ui.Ui_mainWindow):
                             '<a href="https://github.com/ciromattia/kcc/wiki/Important-tips">important tips</a>.',
                             'info')
         
-        self.tar = 'tar' in available_archive_tools()
+        self.tar = TAR in available_archive_tools()
         self.sevenzip = SEVENZIP in available_archive_tools()
         if not any([self.tar, self.sevenzip]):
             self.addMessage('<a href="https://github.com/ciromattia/kcc#7-zip">Install 7z (link)</a>'