.SH "Communicating With Other Users" .P There are several ways in which users can "talk" to other users. One way (write) corresponds to making a telephone call and the other (mail) corresponds to mailing a letter. .H 2 "Mailing A User" The process of mailing somebody has been explained earlier, but here is a short rundown on the procedure. To mail a user you type .DS % mail [login-name] .DE followed by all of the mail you want sent. To finish sending the mail you must type .DS [control]d .DE ie. hold down the control key and type a 'd'. In general [control]d is the way that you indicate to most programs that you have no more data for them. You can 'mail' a user regardless of whether he/she is logged on. .H 2 "Writing To Another User" Writing to a user is a very convenient way of having a conversation with another user 'cu who is logged in. To write to a user 'joe' type .DS % write joe .DE If the user is not logged in the system will tell you so and the terminal will respond .DS joe not logged in % .DE You can't write to someone unless he is logged in. You may also receive the message .DS permission denied % .DE This means that joe is logged in but that he doesn't want to be interrupted. This can be done via the command 'mesg'. The command .DS % mesg n was y % .DE means that nobody can write to you now. The 'was y' comes from 'mesg' and reminds you of your previous status. You can change your mind by typing 'mesg y' or just 'mesg'. \&'mesg' by itself changes from either 'y' or 'n' to 'n' or 'y' respectively. .P If the user were logged on, then he would receive the message .DS Message from [your-login-name]... .DE When writing to someone it is usual to wait for his reply, before you start talking to him. .P After you have typed in .DS % write joe .DE everything that you now type will also appear on his terminal. As an example the following may happen (lines in capitals are generated by the other user) .DS % write joe Message from joe.... ('joe' has just written back) have you still got that book on Accounting, or did you take it back to the library???????? I WAS JUST ON MY WAY TO THE LIBRARY NOW TO RETURN IT. well don't run off with it, I need it for an assignment. OK, WILL DO thanks. .DE Now that you have finished the conversation you type .DS [control]d .DE and the terminal will respond, as usual .DS % .DE and 'joe' will receive .DS EOT .DE When 'joe' types in a [control]d you will receive .DS EOT .DE as well. The EOT indicates that the user writing to you has finished talking with you. .H 2 "Who is 'root'" \&'root' is the name of a rather special user of the system. This user has powers and abilities far beyond those of mortal men\*F. .FS have .ul you seen the movie? .FE Nothing you can do can ever stop 'root' being able to read or write on your files. The mode on any file or directory is totally ignored whenever 'root' wishes to access anything. As well as ignoring modes on files, \$'root' has the ability to change your password, which can be handy if you forget it! .P Like Superman, 'root' is generally friendly and uses his powers for good. \&'root' allocates new accounts, initiates the backup copying of files on week nights. .P In reality, the system staff use 'root'\*F to perform their duties. .FS although they, like him, have apparently super\-normal abilities. .FE Thus messages and mail of a system nature (hardware or other such problems) should be directed to 'root'. The name 'root' comes from the fact that he is the root of the system.