Append exports to end of .bash_profile instead of overwriting

In the process at an explanation of where the lines came from
so that users know they can remove the lines if desired.

diff --git a/setup/bin/swc-nano-installer.py b/setup/bin/swc-nano-installer.py
index f27aac1bf72632bc5d7cd58ea9e2b0b0298d2c26..67dd7e8b5683687ddea0a27bafeb101a9ffd53b5 100644 (file)
--- a/setup/bin/swc-nano-installer.py
+++ b/setup/bin/swc-nano-installer.py
@@ -48,12 +48,13 @@ def make_bash_profile(home_dir, nano_dir):
     """
 
     nano_path = make_posix_path(nano_dir)
-    contents = '\n'.join([
-        'export PATH=$PATH:%s' % nano_path,
-        'export EDITOR=nano',
-            '',
-            ])
-    with open(os.path.join(home_dir, '.bash_profile'), 'w') as f:
+    contents = '\n'.join(['',
+                          '# Add nano to path and set as default editor',
+                          '# Added by the Software Carpentry nano installer',
+                          'export PATH=$PATH:%s' % nano_path,
+                          'export EDITOR=nano',
+                          ''])
+    with open(os.path.join(home_dir, '.bash_profile'), 'a') as f:
         f.write(contents)
 
 def make_posix_path(windows_path):