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Sistemi operativi - Syscall wait Appunti scolastici Premium

Appunti di sistemi operativi per l'esame dei professori Cotroneo e Natella. gli argomenti trattati sono i seguenti: System call wait: name, sypnosis, description, return value, errors, examples, application usage, future directions, see also, derivation.

Esame di Sistemi operativi docente Prof. D. Cotroneo

Anteprima

ESTRATTO DOCUMENTO

wait http://www.opengroup.org/onlinepubs/007908799/xsh/wait.html

The Single UNIX ® Specification, Version 2

Copyright © 1997 The Open Group

NAME

wait, waitpid - wait for a child process to stop or terminate

SYNOPSIS

#include <sys/types.h>

#include <sys/wait.h>

pid_t wait(int *stat_loc);

pid_t waitpid(pid_t int *stat_loc, int

pid, options);

DESCRIPTION

The wait() and waitpid() functions allow the calling process to obtain status information

pertaining to one of its child processes. Various options permit status information to be

obtained for child processes that have terminated or stopped. If status information is available

for two or more child processes, the order in which their status is reported is unspecified.

The wait() function will suspend execution of the calling thread until status information for

one of its terminated child processes is available, or until delivery of a signal whose action is

either to execute a signal-catching function or to terminate the process. If more than one

waitpid() awaiting termination of the same process, exactly

thread is suspended in wait() or

one thread will return the process status at the time of the target process termination. If status

information is available prior to the call to wait(), return will be immediate.

The waitpid() function will behave identically to wait(), if the pid argument is (pid_t)-1 and

the options argument is 0. Otherwise, its behaviour will be modified by the values of the pid

and options arguments.

The pid argument specifies a set of child processes for which status is requested. The

waitpid() function will only return the status of a child process from this set:

If pid is equal to (pid_t)-1, status is requested for any child process. In this respect,

waitpid() is then equivalent to wait().

If pid is greater than 0, it specifies the process ID of a single child process for which

status is requested.

If pid is 0, status is requested for any child process whose process group ID is equal to

that of the calling process.

If pid is less than (pid_t)-1, status is requested for any child process whose process

group ID is equal to the absolute value of pid.

The options argument is constructed from the bitwise-inclusive OR of zero or more of the

following flags, defined in the header <sys/wait.h>.

WCONTINUED

The waitpid() function will report the status of any continued child process specified by

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DETTAGLI
Corso di laurea: Corso di laurea in ingegneria informatica
SSD:
A.A.: 2013-2014

I contenuti di questa pagina costituiscono rielaborazioni personali del Publisher N. A. di informazioni apprese con la frequenza delle lezioni di Sistemi operativi e studio autonomo di eventuali libri di riferimento in preparazione dell'esame finale o della tesi. Non devono intendersi come materiale ufficiale dell'università Napoli Federico II - Unina o del prof Cotroneo Domenico.

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