Search results
Results from the WOW.Com Content Network
The exec calls named ending with an e alter the environment for the new process image by passing a list of environment settings through the envp argument. This argument is an array of character pointers; each element (except for the final element) points to a null-terminated string defining an environment variable .
A high-level overview of the Linux kernel's system call interface, which handles communication between its various components and the userspace. In computing, a system call (commonly abbreviated to syscall) is the programmatic way in which a computer program requests a service from the operating system [a] on which it is executed.
Callbacks are often used to program the graphical user interface (GUI) of a program that runs in a windowing system. The application supplies a reference to a custom callback function for the windowing system to call. The windowing system calls this function to notify the application of events like mouse clicks and key presses.
The fork and execve functions in glibc are examples of this. They call the lower-level fork and execve system calls, respectively. This may lead to incorrectly using the terms "system call" and "syscall" to refer to higher-level library calls rather than the similarly named system calls, which they wrap. [4] [5]
When a process calls fork, it is deemed the parent process and the newly created process is its child. After the fork, both processes not only run the same program, but they resume execution as though both had called the system call. They can then inspect the call's return value to determine their status, child or parent, and act accordingly.
The former allocates the first available descriptor, just like open() behaves; an alternative way to duplicate a file descriptor to an unspecified place is the fcntl system call with F_DUPFD command. The latter places the copy into newfd. If newfd is open, it is closed first.
The GNU C Library is a wrapper around the Linux kernel system call interface. A C standard library for Linux includes wrappers around the system calls of the Linux kernel; the combination of the Linux kernel system call interface and a C standard library is what builds the Linux API. Some popular implementations of the C standard library are glibc
stat() is a Unix system call that returns file attributes about an inode. The semantics of stat() vary between operating systems. As an example, Unix command ls uses this system call to retrieve information on files that includes: atime: time of last access (ls -lu) mtime: time of last modification (ls -l) ctime: time of last status change (ls -lc)