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authorMateusz Piotrowski <0mp@FreeBSD.org>2021-04-17 21:10:48 +0000
committerMateusz Piotrowski <0mp@FreeBSD.org>2021-04-17 21:12:06 +0000
commitc4207d867c201a726aa3157e09262f72166c89c4 (patch)
treede7ad67cc3741d7d976803846faba5a31662a5aa /lib/libc
parentd25f7d324a9d0c33655876b920ba590918d16f4c (diff)
downloadsrc-c4207d867c201a726aa3157e09262f72166c89c4.tar.gz
src-c4207d867c201a726aa3157e09262f72166c89c4.zip
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
Diffstat (limited to 'lib/libc')
-rw-r--r--lib/libc/sys/fork.238
1 files changed, 37 insertions, 1 deletions
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