Date: Sat, 17 Apr 2021 21:13:06 GMT From: Mateusz Piotrowski <0mp@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-main@FreeBSD.org Subject: git: c4207d867c20 - main - fork.2: Add a simple use pattern Message-ID: <202104172113.13HLD6UI014137@gitrepo.freebsd.org>
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The branch main has been updated by 0mp (doc, ports committer): URL: https://cgit.FreeBSD.org/src/commit/?id=c4207d867c201a726aa3157e09262f72166c89c4 commit c4207d867c201a726aa3157e09262f72166c89c4 Author: Mateusz Piotrowski <0mp@FreeBSD.org> AuthorDate: 2021-04-17 21:10:48 +0000 Commit: Mateusz Piotrowski <0mp@FreeBSD.org> CommitDate: 2021-04-17 21:12:06 +0000 fork.2: Add a simple use pattern It seems to be a nice idea to show how fork() is usually used in practice. This may act as a guide to developers who want to quickly recall how to use the fork() function. Reviewed by: bcr, yuripv MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D27626 --- lib/libc/sys/fork.2 | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) diff --git a/lib/libc/sys/fork.2 b/lib/libc/sys/fork.2 index 3e55530827c5..d43ade6a483e 100644 --- a/lib/libc/sys/fork.2 +++ b/lib/libc/sys/fork.2 @@ -28,7 +28,7 @@ .\" @(#)fork.2 8.1 (Berkeley) 6/4/93 .\" $FreeBSD$ .\" -.Dd December 1, 2017 +.Dd April 17, 2021 .Dt FORK 2 .Os .Sh NAME @@ -99,6 +99,42 @@ to the parent process, no child process is created, and the global variable .Va errno is set to indicate the error. +.Sh EXAMPLES +The following example shows a common pattern of how +.Fn fork +is used in practice. +.Bd -literal -offset indent +#include <err.h> +#include <stdio.h> +#include <stdlib.h> +#include <unistd.h> + +int +main(void) +{ + pid_t pid; + + switch (pid = fork()) { + case -1: + err(1, "Failed to fork"); + case 0: + printf("Hello from child process!\en"); + exit(0); + default: + break; + } + + printf("Hello from parent process (child's PID: %d)!\en", pid); + + return (0); +} +.Ed +.Pp +The output of such a program is along the lines of: +.Bd -literal -offset indent +Hello from parent (child's PID: 27804)! +Hello from child process! +.Ed .Sh ERRORS The .Fn fork
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