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fork(3f) [bsd man page]

FORK(3F)																  FORK(3F)

NAME
fork - create a copy of this process SYNOPSIS
integer function fork() DESCRIPTION
Fork creates a copy of the calling process. The only distinction between the 2 processes is that the value returned to one of them (referred to as the `parent' process) will be the process id of the copy. The copy is usually referred to as the `child' process. The value returned to the `child' process will be zero. All logical units open for writing are flushed before the fork to avoid duplication of the contents of I/O buffers in the external file(s). If the returned value is negative, it indicates an error and will be the negation of the system error code. See perror(3F). A corresponding exec routine has not been provided because there is no satisfactory way to retain open logical units across the exec. How- ever, the usual function of fork/exec can be performed using system(3F). FILES
/usr/lib/libU77.a SEE ALSO
fork(2), wait(3F), kill(3F), system(3F), perror(3F) 4.2 Berkeley Distribution May 27, 1986 FORK(3F)

Check Out this Related Man Page

FORK(2) 							System Calls Manual							   FORK(2)

NAME
fork - create a new process SYNOPSIS
#include <sys/types.h> #include <unistd.h> pid_t fork(void) DESCRIPTION
Fork causes creation of a new process. The new process (child process) is an exact copy of the calling process except for the following: The child process has a unique process ID. The child process has a different parent process ID (i.e., the process ID of the parent process). The child process has its own copy of the parent's descriptors. These descriptors reference the same underlying objects, so that, for instance, file pointers in file objects are shared between the child and the parent, so that an lseek(2) on a descriptor in the child process can affect a subsequent read or write by the parent. This descriptor copying is also used by the shell to establish standard input and output for newly created processes as well as to set up pipes. The child starts with no pending signals and an inactive alarm timer. RETURN VALUE
Upon successful completion, fork returns a value of 0 to the child process and returns the process ID of the child process to the parent process. Otherwise, a value of -1 is returned to the parent process, no child process is created, and the global variable errno is set to indicate the error. ERRORS
Fork will fail and no child process will be created if one or more of the following are true: [EAGAIN] The system-imposed limit on the total number of processes under execution would be exceeded. This limit is configuration- dependent. (The kernel variable NR_PROCS in <minix/config.h> (Minix), or <minix/const.h> (Minix-vmd).) [ENOMEM] There is insufficient (virtual) memory for the new process. SEE ALSO
execve(2), wait(2). 3rd Berkeley Distribution May 22, 1986 FORK(2)

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