The Programming Knowledge

Shell is a UNIX term for the interactive user interface with an operating system. The shell is the layer of programming that understands and executes the commands a user enters. In some systems, the shell is called a command interpreter. A shell usually implies an interface with a command syntax (think of the DOS operating system and its "C:>" prompts and user commands such as "dir" and "edit"). •           The shell is a user program or it is an environment provided for user interaction. •           It is a command language interpreter that executes commands read from the standard input device such as keyboard or from a file. •           The shell gets started when you log in or open a console (terminal). •           Quick and dirty way to execute utilities. •     ...

LIFE-CYCLE OF C PROGRAM There are at least five phases of execution of  a C language program:- 1. Pre-Processing 2. Compilation 3. Linking 4. Loading 5. Execution   Pre-processing :- Pre-processing is under control of pre-processor directives. It is a program which will be executed automatically before passing the source program to compiler. The pre-processor statements are processed first. All the statements starting with # (pound) symbol are called pre-processor statements. Pre-processor is not a part of C compiler. After pre-processing, there generates a file with .I extension file.( read header file and #include article – coming soon ). Compilation:- The grammatical rules or syntactical validity of the complete program is checked. If there is any error, the location and type of error is reported to the programmer. These are called syntax error. If there is no error, then the compiler generate  object code  and prepare symbolic ta...

PL / SQL . Triggers are stored programs, which are automatically executed or fired when some events occur . Triggers are, in fact, written to be executed in response to any of the following events − ·         A  database manipulation (DML)  statement (DELETE, INSERT, or UPDATE) ·         A  database definition (DDL)  statement (CREATE, ALTER, or DROP). ·         A  database operation  (SERVERERROR, LOGON, LOGOFF, STARTUP, or SHUTDOWN). Triggers can be defined on the table , view , schema , or database with which the event is associated.                        A trigger is a special kind of a stored procedure that executes in response to certain action on the table like insertion , deletion or updation of data. It is a d...