add df example

bindings/python/examples/df.py

@@ -0,0 +1,23 @@
+import os, sigar;
+
+sg = sigar.open()
+fslist = sg.file_system_list()
+
+def format_size(size):
+    return sigar.format_size(size * 1024)
+
+print 'Filesystem\tSize\tUsed\tAvail\tUse%\tMounted on\tType\n'
+
+for fs in fslist:
+    dir_name = fs.dir_name()
+    usage = sg.file_system_usage(dir_name)
+
+    total = usage.total()
+    used = total - usage.free()
+    avail = usage.avail()
+    pct = usage.use_percent() * 100
+    if pct == 0.0:
+        pct = '-'
+
+    print fs.dev_name(), format_size(total), format_size(used), format_size(avail),\
+        pct, dir_name, fs.sys_type_name(), '/', fs.type_name()