Direct mail is a broad term that includes the following types of mailed promotions: Institutional direct mail serves to promote the name of the publishing house with no reasonable expectation of sales revenues.
The touch command is the easiest way to create new, empty files. It is also used to change the timestamps (i.e., dates and times of the most recent access and modification) on existing files and directories. touch's syntax is. touch [option] file_name(s)
While unix-line-discard is a good mnemonic, the use of CTRL+U as a line-erase character precedes the invention of UNIX. It was used as such on various Digital Equipment (DEC) systems, including the PDP-8. For instance, from my dusty bookshelf I see that CTRL+U was used as line-erase in the PDP-8 Symbolic Editor (page 5-13 of the 1972 edition of the PDP-8 Introduction To Programming (Volume 1) manual published by DEC). In fact, in the early days of UNIX, the @ character was often the default line-erase character.