1 files changed, 8 insertions, 5 deletions
diff --git a/file.c b/file.c
index 7b4303acd..0e3a2d209 100644
--- a/file.c
+++ b/file.c
@@ -3499,15 +3499,18 @@ rb_thread_flock(void *data)
  *
  *  Example:
  *
- *     # write lock
+ *     # update a counter using write lock
  *     # don't use "w" because it truncates the file before lock.
- *     File.open("testfile", File::WRONLY|File::CREAT, 0644) {|f|
+ *     File.open("counter", File::RDWR|File::CREAT, 0644) {|f|
  *       f.flock(File::LOCK_EX)
- *       f.truncate(0)
- *       f.write "new content"
+ *       value = f.read.to_i + 1
+ *       f.rewind
+ *       f.write("#{value}\n")
+ *       f.flush
+ *       f.truncate(f.pos)
  *     }
  *
- *     # read lock
+ *     # read the counter using read lock
  *     File.open("testfile", "r") {|f|
  *       f.flock(File::LOCK_SH)
  *       p f.read