The Command Line Interface q Windoze-like GUI’s are exist, but we will not discuss them.r In the past year or so, both Gnome and KDE have become excellent desktops. q The shell is the program that you interact with. It is between you and the UNIX/Linux kernel. It uses a command line interface. There are different shells, but we will use bash, which stands for “Bourne again shell.” r One of the original shells was written by Steve Bourne of AT&T Bell Labs. It was named sh q The shell maintains an idea of your present working directory. This distinguishes it from Windoze-like interfaces. q Everything is customisable.q The default bash prompt is: [you@faraday pwd]$ _ where you is your login name, faraday is the name of the computer,and pwd is name of your present working directory: we will discuss directory names further in Module 2. When you first log in, your present workingdirectory is called your home directory, and typically has the same name as your login. r Throughout these documents, the underscore _ represents the cursor, waiting for you to type something. q You enter a command by typing its name and pressing Enter. In the early days the input/output device was a teletype and many of the geeks were not good typists, so command names are often very short. q Getting the date and time looks like: [you@faraday pwd]$ dateThu Apr 25 13:50:51 EDT 2002[you@faraday pwd]$ _ Note in the above example that the shell prompt is shown after the command has executed, so you may enter another command. Logging Out q To log out, you just need to exit the shell. Type: [you@faraday pwd]$ exit q Alternatively, you can give the shell an “end of file” command, which tells it that the input is over. On a keyboard you send an end of file by simultaneously holding down the Ctrl key and the letter d. In documentation, the following forms are commonly used to indicate this sequence: r Ctrl+D: note that despite the notation it is a lower-case d.r ^dr C-d Command Syntax q Most commands take arguments r Some commands require themr For example, echo simply displays its arguments: [you@faraday pwd]$ echo[you@faraday pwd]$ echo hi there hi there[you@faraday pwd]$ _ q UNIX/Linux is case-sensitive, including commands: [you@faraday pwd]$ echo whisperwhisper[you@faraday pwd]$ ECHO SHOUT bash: ECHO: command not found[you@faraday pwd]$ _ q Many commands have options, which begin with a hyphen – or double hypens –. Options are given immediately after the name of the command and before any arguments. For example, echo has an option -n which means donot output the trailing newline. [you@faraday pwd]$ echo -n hi therehi there[you@faraday pwd]$ _.
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