Nếu gõ ký tự đầu tiên của chèn một thay thế bằng văn bản cuối cùng được đưa vào (lên đến 128 ký tự), và chèn chấm dứt. A ^ @ (ASCII 0) không thể là một phần của tập tin. Chèn một tab, trong quá trình chèn. Không phải là một nhân vật lệnh. Trong chế độ đầu vào, ^ Q trích dẫn các nhân vật tiếp theo (tương tự như ^ V), | UNIX System Administration Managing user accounts Adding users Run etc adduser by typing adduser. You are asked for a username user ID use the default supplied full name the login group usually users although you can make a new group at this point and any other groups you want the user to be a member of the location of the home directory the default shell and a password. adduser sets up a home directory and copies default .cshrc .login and .profile files into it from usr skel. The username can contain only lower case ASCII characters a - z and digits 0 - 9 . Deleting users Run etc removeuser by typing removeuser. You are asked for the name of the user you wish to remove and whether you wish to destroy the home directory. Make sure there s nothing you want in there first Adding groups Run etc addgroup by typing addgroup. You are asked for the group s name and number. Removing groups Edit etc group manually Changing passwords Run bin passwd by typing passwd -afs name . If no name is supplied passwd operates on your user if you have su d the user you now appear to be . With no other options passwd asks you for an old password unless you are root and a new one. Options - a Supply a list of system-generated passwords. Use this if you want real security - f Change the finger information real name phone number etc. not the password. This is equivalent to the chfn command. -s Change the login shell not the password. Security note anyone who uses an English word or a name connected to them doesn t care about real security or doesn t understand it. The best passwords are random like bx23H5sj - remember UNIX is case-sensitive. The next best are system-generated the system generates pseudo-words that are a little easier to remember such as kuboit. Other good passwords are mis-spelled words such as oppised. Words in a dictionary are vulnerable to a dictionary search and this is a trivial problem for any modern personal computer. The etc passwd file Use vipw to edit etc passwd .
