1. Creating general users

You can use useradd and passwd commands to create general users.
For example, creating a new user account named  wsuser.

useradd wsuser

passwd wsuser

• use man command to find out about how to use commands
• man stands for "manual", a series of online "pages" which can tell you the purpose of many commands.
• Todo: check the man pages of the command man

man man

• Where you are? To find where you are, use the command

pwd

• Command pwd return the absolute path of your current working directory. every absolute path are started with '/'. '/' means the root (top) of the Linux filesystem. Every accessible directories and files are stored uder the root directory to form a hierarchical file structure (just like a tree, you may just call it a directory tree).
• To change your current working directory to the place you want to go, use the change directory command

cd

• Relative path is the path relative to your current directory. If you want to move up, you can change directory to '..' (the parent directory).

$ cd /etc/X11     $ pwd     /etc/X11     $ cd /etc     $ pwd     /etc     $ cd /etc/X11     $ cd ..     $ pwd     /etc

• To check the contents of a directory or a file in a directory, use the list command

$ ls     $ ls /etc/X11

• Options used with ls. Yoy can view the full list by reading the ls man page (man ls)
• -a, --all: List all files in the directory, including the hidden files (files starting with '.').
• -l, --long: Lists details about contents, including permission (modes), owner, group, size, creation date, whether the file is linked to somewhere else on the system and where its link points.
• -F, --classify: Adds a symbol to the end of each listing. These symbols include / to indicate a directory, @ to indicate a symbolic link to another file, * to indicate an executable file.
• -R, --recursive: Lists the contents of all directories (below the current directory) recursively.
• Todo:

$ cd /etc/X11     $ ls     $ ls -F     $ ls -a     $ ls -la     $ ls -lR     $ ls -la /etc     $ ls -la /etc | more     $ ls -la /etc | less

• To create a directory under the current directory, use make directory command mkdir.

cd /tmp     mkdir test     ls -F     cd test

• To create a file, you can use any text editor. Such a pico, gedit, kedit, or simply cat.

$ pico test

• To copy a file, use the copy command

$ cp test test1     $ cp /etc/X11/XF86Config .     $ ls

• To rename a file or a directory, use the move command

$ mv test1 test2     $ ls     $ cd ..     $ mv temp temp1     $ cd temp1     $ ls

• To delete a file, use the remove command

$ rm test2     $ ls

• To delete a directory, use the remove directory command

$ rm test     $ ls     $ cd ..     $ rmdir temp1     $ ls

• To cleanup the screen, use the clean command

clear

• If your terminal screen have been screwed up by strange characters, you can reset the terminal windows by the reset command

reset

try this

cat /bin/ls  ^C    [Control]-C

• command cat, short for "concatenate", means concatenate files and print on the standard output.
• Standard input and standard output direct input and output (often referred to as I/O) to the user. If a program reads from standard input, it will, by default be reading from the keyboard. If a program writes to standard output, by default it will be writing to the screen.
• Try cat command and type anything on the screen

$ cat

• To return to the shell prompt, type ^D (Control-D).

• Unix shells and utilities are developed in a consistent way which conform to certain guidelines. This is important because by following the guidelines, tools can easily be integrated together to accomplish larger tasks. And remember that building a program to achieve a large task is a complex process. The resulting program cab be inflexible and buggy.
• Every interactive tools should have input and output. In the Unix shell environment, you can redirect input or output of a program from or to a file.
• By redirect standard output and command cat, you can create short file without a text editor.

$ cat > file1     from file1     ^D     $ cat > file2u     from file2     ^D     $ cat file1     $ cat file2

• you can use cat to combine two files and rediecting the output the a new file.

$ cat file1 file2     $ cat file1 file2 > file3     $ cat file3

• the output redirection > is used to create a file or replace the contents of the existing file with the output from the previous command. To append the output to the end of the exists file without overwrite its existing contents, you should use the append symbol '>>'.

$ cat file1 > file3     $ cat file2 >> file3     $ cat file3

• you can also the standard input for a command from a file using standard input redirection '<'.

$ cat < file3

• in the above example, without the filename as the parameter, command cat will check input from standard input. And in this case, the standard input have been rediected to the file file3, so the contents of file3 will be displayed.

• Pipe is an important shell functions to integrate tools to make it working together.
• Pipes connect the stardard output of one command to the standard input of another command.

$ ls -la /etc | less     $ ls -la /etc | grep hosts | less

• To enter multiple commands in a single line, you can separate the commands with a semicolon ';'. In this case, the commands are separated just as you enter it separately the shell prompt.

$ cat; ls     $ ls ; cat