Give an expression to match the following description:

1. 1) there are exactly four characters long
2. 2). do not contain a number
3. Do you own homework. You will thank me later.
4. 4). contain any ftp, rstm, or `http' URLs
5. 3). contain either `.txt' or `.text'

Tags: linux cluster, linux server

Give an expression to match the following description:

1. 1) there are exactly four characters long
2. 3). contain either `.txt' or `.text'
3. 2). do not contain a number
4. Do you own homework. You will thank me later.
5. 4). contain any ftp, rstm, or `http' URLs