System function return value in c

2019-08-23 15:08

It will return an integer value, which is interpretation is different on various systems, thus system dependent. If you want to check whether there is a command processor exist then you use the NULL argument in the function. Parameters: A C string that is containing a system command name. Return value:Overview. In C, return exp; (where exp is an expression) is a statement that tells a function to return execution of the program to the calling function, and report the value of exp. If a function has the return type void, the return statement can be used without a value, in which case the program just breaks out of the current function and returns to the calling one. system function return value in c

The value returned is 1 on error, and the return status of the command otherwise. Example The following example shows the usage of system() function to list down all the files and directories in the current directory under unix machine.

In C, a function always returns its value to the calling function and never to itself (if return type is not void). Like, int main() But since 'main' function is called by the Operating System, which is not a function. So, whom does the 'main' function returns its value? Where does the value go, when its returned using the expression system() executes a command specified in command by calling binsh c command, and returns after the command has been completed. During execution of the command, SIGCHLD will be blocked, and SIGINT and SIGQUIT will be ignored. system function return value in c Finally, note that a function is free to define what its return value means. Some functions use return values as status codes, to indicate whether they succeeded or failed. Other functions return a calculated or selected value. Other functions return nothing. What the function returns and the meaning of that value is defined by the functions

8 Answers. The return value of system is (ironically) systemdependent, but in POSIX systems (including Linux, etc), it's the same as for wait low 8 or 16 bits are the exit status of the child (probably what you mean by value returned by ), higher bits indicating what kind of signal terminated the child, if system function return value in c RETURN VALUE. The return value of system() is one of the following: If command is NULL, then a nonzero value if a shell is available, or 0 if no shell is available. If a child process could not be created, or its status could not be retrieved, the return value is 1. System call return value in C. Ask Question 4. I am using system function in C code to invoke cp command. I want to know whether it got executed successfully or not? c linux. share improve this question. edited Feb 15 '10 at 8: 37. Tim. 7, 971 24 45. asked Feb 15 '10 at 8: 04. Susmi Return Value. If command is a null pointer, the function returns a nonzero value in case a command processor is available and a zero value if it is not. If command is not a null pointer, the value returned depends on the system and library implementations, but it is generally expected to be the status code returned by the called command, if supported. In this case, the return value of the called function is undefined. If a return value is not required, declare the function to have void return type; otherwise, the default return type is int. Many programmers use parentheses to enclose the expression argument of the return statement. However, C does not require the parentheses.

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