add exit trap trick (#45)

README.md

@@ -1095,6 +1095,18 @@ source ~/.bashrc
 cd $hotellogs
 ```
 
+## Exit traps
+
+Make your bash scripts more robust by reliably performing cleanup.
+
+```bash
+function finish {
+  # your cleanup here. e.g. kill any forked processes
+  jobs -p | xargs kill
+}
+trap finish EXIT
+```
+
 # 4. Debugging
 You can easily debug the bash script by passing different options to `bash` command. For example `-n` will not run commands and check for syntax errors only. `-v` echo commands before running them. `-x` echo commands after command-line processing.