@OS X El Capitan users: You might want to check out the new custom Temp folder feature, which allows you to select a temp folder other than
/temp.
This feature might help you avoid data loss, because OS X El Capitan might delete temporary Sigil files (and other temp files) under certain circumstances. For more information see the
Data loss in 0.9.5 on OS X (El Capitan) thread.
You can select a new temp folder via:
Edit > Preferences > General Settings > Set folder where temporary files should be created