Leo Chan questions

• Does Gmail not allow sender to set a return path value to receive bounce messages?
• How to use datatables (jquery datagrid plugin ) to implement an check all and delete function?
• How to modify a file by using awk?
• Use php to set cron jobs in Windows
• Can I use sed to manipulate a variable in bash?
• How can I count the occurrences of a string within a file?

Leo Chan answers