The following command lists the contents of the current directory. The program name is type and the argument is readme.txt. The following command displays the contents of the file readme.txt. Here are some commands for the DOS, OS/2 and Microsoft Windows command prompt processor. The program name is cat, having two file name arguments: The following command displays the contents of the files ch1.txt and ch2.txt. The program is ls, having three flags ( l, t, r), and the argument is the directory /bin: The quotes are used to prevent Hello and World being treated as separate tokens: The program name is echo and the argument is "Hello World". The following command prints the text Hello World on the standard output stream, which, in this case, just prints the text on the screen. The utility program is cd and the argument is /home/pete: The following command changes the user's working position in the directory tree to the directory /home/pete. Here are some commands given to a command-line interpreter ( Unix shell). As an analogy to a natural language, the flags are adverbs, while the other arguments are objects. Many programs allow specially formatted arguments, known as flags or options, which modify the default behaviour of the program, while further arguments may provide objects, such as files, to act on. If one views a statement in an imperative language as being like a sentence in a natural language, then a command is generally like a verb in such a language. The name arises because statements in these languages are usually written in a manner similar to the imperative mood used in many natural languages. Specifically, the term command is used in imperative computer languages. It may be issued via a command-line interface, such as a shell, or as input to a network service as part of a network protocol, or as an event in a graphical user interface triggered by the user selecting an option in a menu. In computing, a command is a directive to a computer program to perform a specific task.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |