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Power 6/32 Unix version 1.2b

.TH FORK 2 
.SH NAME
fork \- create a new process
.SH SYNOPSIS
.B int fork (\|)
.SH DESCRIPTION
.I Fork\^
causes creation of a new process.
The new process (child process) is an
exact copy of the calling process (parent process).
This means the child process inherits the following attributes from the parent
process:
.PP
.PD 0
.RS 0.5i
.PP
environment
.PP
close-on-exec flag (see
.IR exec (2))
.PP
signal handling settings (i.e.,
.SM
.BR SIG_DFL ", " SIG_ING ,
function address)
.PP
set-user-\s-1ID\s+1 mode bit
.PP
set-group-\s-1ID\s+1 mode bit
.PP
profiling on/off status
.PP
nice value (see 
.IR nice (2))
.PP
all attached shared memory segments (see
.IR shmop (2))
.PP
process group
.SM ID
.PP
tty group
.SM ID
(see 
.IR exit (2)
and
.IR signal (2))
.PP
trace flag (see
.IR ptrace "(2) request 0)"
.PP
time left until an alarm clock signal (see 
.IR alarm (2))
.PP
current working directory
.PP
root directory
.PP
file mode creation mask (see
.IR umask (2))
.PP
file size limit (see 
.IR ulimit (2))
.RE
.PD
.PP
The child process differs from the parent process in the following ways:
.IP
The child process has a unique process
.SM ID\*S.
.IP
The child process has a different parent process
.SM ID
(i.e., the
process
.SM ID
of the parent process).
.IP
The child process has its own copy of the parent's file descriptors.
Each of the child's file descriptors shares a common file pointer with the
corresponding file descriptor of the parent.
.IP
All semadj values are cleared (see
.IR semop (2)).
.IP
Process locks, text locks and data locks are not inherited by the child (see
.IR plock (2)).
.IP
The child process's
.IR utime , " stime" , " cutime" ,
and
.I cstime\^
are set to 0.
The time left until an alarm clock signal is reset to 0.
.PP
.I Fork\^
will fail and no child process will be created if one or more of the
following are true:
.sp
.TP 15
\s-1\%[EAGAIN]\s+1
The system-imposed limit on the total number of processes under execution
would be exceeded.
.TP
\s-1\%[EAGAIN]\s+1
The system-imposed limit on the total number of processes under execution
by a single user would be exceeded.
.SH RETURN VALUE
Upon successful completion,
.I fork\^
returns a value of 0 to the child process and returns the process
.SM 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
.I errno\^
is set to indicate the error.
.SH NOTES
This manual page replaces the 4.2BSD manual page.
.SH "SEE ALSO"
exec(2), nice(2), plock(2), ptrace(2), semop(2), shmop(2), signal(2), times(2), ulimit(2), umask(2), wait(2).
.\"	@(#)fork.2	6.2 of 9/6/83

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