Unix Tree Catalog Structure / BIN, / ETC, / USR, / VAR, / HOME
/ bin system executable
/ ETC system configuration file
/ USR system application
/ VAR system log and mail, etc.
/ PROC system running process (/ proc / interrupts)
Introduction to the main files in the / etc Directory Passwd, Shadow, Group User Management Hostwd, Hostname, Hosts.deny, Hosts.allow Network FTPAccess, FTPUSER, FTPHOSTS FTP Server FSTAB File System Table inetd.conf Network Service Startup Configuration RC.D System Startup Script Directory Issue, Issue.net, MOTD Information Display Pine.conf Pine.conf.Fixed My.cnf Application Configuration Program
Multitasking
In UNIX systems, there can be several different tasks performed at the same time. A user can execute several programs in a terminal, which seems to be running at the same time. This means that a user can format another file when editing a text file while printing another file.
In fact, the CPU can only perform one task at the same time, but the UNIX system can divide the execution of the CPU into time slice, by scheduling, making it in the same time, as viewing to the user, as if performing different programs while performing different programs .
Multi-user
Multiple users are allowing multiple users to log in and using the system at the same time. Multiple terminals and keyboards can be connected to the same computer. This is a natural extension of multitasking. If the system can run multiple programs at the same time, some programs can also support multiple user clues. Additionally, a single user can log in to the same system at different times through multiple terminals. A great advantage of this architecture is that members of the working group can operate the same data at the same time.
Shell
