a presentation on commands MA command-line interpreter or command-line processor uses a command-line interface (CLI) to receive commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invoking executables and providing information to them as to what actions they are to perform. In some cases the invocation is conditional based on conditions established by the user or previous executables. Such access was first provided by computer terminals starting in the mid-1960s. This provided an interactive environment not available with punched cards or other input methods. Today, many users rely upon graphical user interfaces and menu-driven interactions. However, some programming and maintenance tasks may not have a graphical user interface and use a command line. Alternatives to the command-line interface include text-based user interface menus (for example, IBM AIX SMIT), keyboard shortcuts, and various desktop metaphors centered on the pointer (usually controlled with a mouse). Examples of this include the Microsoft Windows, DOS Shell, and Mouse Systems PowerPanel. Command-line interfaces are often implemented in terminal devices that are also capable of screen-oriented text-based user interfaces that use cursor addressing to place symbols on a display screen. Programs with command-line interfaces are generally easier to automate via scripting. Many software systems implement command-line interfaces for control and operation. This includes programming environments and utility programs. Comparison to graphical user interfaces A graphical user interface with icons and windows (GEM 1.1 Desktop) Compared with a graphical user interface, a command-line interface requires fewer system resources to implement. Since options to commands are given in a few characters in each command line, an experienced user often finds the options easier to access. Automation of repetitive tasks is simplified by line editing and history mechanisms for storing frequently used sequences; this may extend to a scripting language that can take parameters and variable options. A command-line history can be kept, allowing review or repetition of commands. A command-line system may require paper or online manuals for the user's reference, although often a "help" option provides a concise review of the options of a command. The command-line environment may not provide graphical enhancements such as different fonts or extended edit windows found in a GUI. It may be difficult for a new user to become familiar with all the commands and options available, compared with the icons and drop-down menus of a graphical user interface, without reference to manuals. Operating system command-line interfaces Apple Computer's CommandShell in A/UX 3.0.1 Operating system (OS) command-line interfaces are usually distinct programs supplied with the operating system. A program that implements such a text interface is often called a comman

1. A PRESENTATION ON
TOPIC : Commands
 MAN
 MORE
 LESS
 WHATIS
-BY M MADHU SUDHAN
4AL20CS072

2. COMMAND MAN
• man command in Linux is used to display the user manual of any command that we can run
on the terminal.
• It provides a detailed view of the command which includes NAME, SYNOPSIS,
DESCRIPTION, OPTIONS, EXIT STATUS, RETURN VALUES, ERRORS, FILES,
VERSIONS, EXAMPLES, AUTHORS .
• Syntax :
$man [OPTION]... [COMMAND NAME]...
• Examples :
1. $ man printf 2. $ man 2 intro 3. $ man -f ls
4. $ man -a intro 5. $ man -k cd

3. COMMAND MORE
• more command is used to view the text files in the command prompt, displaying one screen
at a time in case the file is large (For example logfiles).
• The more command also allows the user do scroll up and down through the page. Another
application of more is to use it with some other command after a pipe.
• When the output is large, we can use more command to see output one by one.
• Syntax: more [-options] [-num] [+/pattern] [+linenum] [file_name]
o[-options]: any option that you want to use in order to change the way the file is
displayed.
Choose any one from the followings: (-d, -l, -f, -p, -c, -s, -u).

4. o [-num]: type the number of lines that you want to display per screen.
o [+/pattern]: replace the pattern with any string that you want to find in the text file.
o [+linenum]: use the line number from where you want to start displaying the text
content.
o [file_name]: name of the file containing the text that you want to display on the
screen.
EXAMPLE:
1. more -d sample.txt
2. more -f sample.txt
3. more -p sample.txt

5. COMMAND LESS
• Less command is a Linux utility that can be used to read the contents of a text file one
page(one screen) at a time.
• It has faster access because if file is large it doesn’t access the complete file, but accesses it
page by page.
• For example, if it’s a large file and you are reading it using any text editor, then the complete
file will be loaded to main memory.
• The less command doesn’t load the entire file, but loads it part by part which makes it faster.
• Syntax :
less filename

6. • Examples :
1. dmesg | less -p "failure“
The above command tells less to start at first occurrence of pattern
“failure” in the file.
2. dmesg | less –N
It will show output along with line numbers
3. less -F filename
It will not give any output, since file can be displayed in single screen.

7. COMMAND WHATIS
• The whatis command is used to get brief information about Linux commands or functions.
• It displays the manual page description in a single line of the command that passes with the
whatis command.
• It searches for the strings that have been passed with it from its index databases.
• Syntax:
whatis [-options]
• If it is used without any argument, it will display a brief description from the manual about
the specified command in one line.

8. Example:
1. whatis -s "1","2" cat : This command will display brief information about the cat
command and functions of manual page 1 and page 2.
2.whatis -w 'ab*'<br>
3.whatis -w 'cd*’ : This commands will display the commands and functions with the
matching patterns.
4.whatis -r 'cd$’ : This command will display a short description of the functions that match
the specified pattern.
5.whatis --usage :The above command will print a short message about usage.

9. THANK YOU