Familiarizing with UNIX Commands

UNIX Commands Unix systems are heavily command based. This often makes us feel uncomfortable. Moreover the system is unfriendly by not providing us with an acknowledgement after execution of the command. But these drawbacks can be acceptable when compared to the power of the OS. What is a command? A command is a binary that has to be executed to accomplish a certain task. There are two types of commands 1) Internal Command 2) External Command

UNIX Commands INTERNAL COMMAND: These are a set of command built in in a Shell. The shell will interpret that command and will execute the result for us. It will not create a child process to execute that command. Examples of Internal command are cd,echo etc. EXTERNAL COMMANDS: The external commands are stored as files. The shell will need to create an child process and then execute an command. The execution time of these command would be a bit more than the external commands. Examples of external command are ls, grep, etc.

UNIX Commands Components of a command A command can have the following components 1) Options 2) Arguments OPTIONS: Options are special kind of arguments that would add more meaning to the command. They come along with the '-' sign. e.g.: ls -l This command would give a long listing of the files in the directory. AGRUMENTS: Arguments are extra words added to the command. e.g. : $ ls –l dir_name Here the directory name is the argument

Some basic commands