创建daemon进程适用于android/linux/mac
# 跨平台通用daemon
```
static int fds[2];
int flag;
pipe(fds);
flag = fcntl(fds[0], F_GETFL, 0);
fcntl(fds[0], F_SETFL, flag | O_NONBLOCK);
flag = fcntl(fds[1], F_GETFL, 0);
fcntl(fds[1], F_SETFL, flag | O_NONBLOCK);
int forkpid = fork();
if (forkpid < 0) {
return -1;
} else if (forkpid > 0) { // father
sleep(1);
return 0;
}
setsid();
chdir("/");
umask(0);
int null_in = open("/dev/null", O_RDONLY);
int null_out = open("/dev/null", O_WRONLY);
dup2(null_in, STDIN_FILENO);
dup2(null_out, STDOUT_FILENO);
dup2(null_out, STDERR_FILENO);
for(unsigned int i = 0; i < 1024; i++) {
close(i);
}
```
### theos makefile命令
```
before-install::
install.exec "echo before-install"
before-uninstall::
install.exec "echo before-uninstall"
after-install::
install.exec "echo after-install"
after-uninstall::
install.exec "echo after-uninstall"
子命令：
install.exec 执行命令
install.copyFile 拷贝文件
注意以上逻辑不会打包到deb文件中，下面来看一种可以打包到deb的方法
```
### deb控制命令
Theos工程下的Layout目录会被打包到deb中
而控制命令包含如下：
preinst
在Deb包文件解包之前，将会运行该脚本。许多“preinst”脚本的任务是停止作用于待升级软件包的服务，直到软件包安装或升级完成。
postinst
该脚本的主要任务是完成安装包时的配置工作。许多“postinst”脚本负责执行有关命令为新安装或升级的软件重启服务。
prerm
该脚本负责停止与软件包相关联的daemon服务。它在删除软件包关联文件之前执行。
postrm
该脚本负责修改软件包链接或文件关联，或删除由它创建的文件。
extrainst_
安装是执行，升级时不执行
在这5个脚本中，传入的参数为install upgrade remove purge
## iOS 创建系统daemon进程
参考：https://developer.apple.com/library/archive/documentation/MacOSX/Conceptual/BPSystemStartup/Chapters/CreatingLaunchdJobs.html
1.配置源文件
a./layout/tmp/test.sh内容
echo $2 >> /tmp/testlog >> /tmp/testlog
sleep 5
b./Library/LaunchDaemons/test.plist内容
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>KeepAlive</key>
<true/>
<key>Label</key>
<string>test</string>
<key>ProgramArguments</key>
<array>
<string>/bin/bash</string>
<string>/tmp/test.sh</string>
</array>
<key>RunAtLoad</key>
<true/>
</dict>
</plist>
c./layout/DEBIAN/prerm内容
#!/bin/sh
if [[ $1 == remove || $1 == purge ]]; then
if [ -f "/Library/LaunchDaemons/test.plist" ]; then
/bin/launchctl unload /Library/LaunchDaemons/test.plist
fi
fi
exit 0
d./layout/DEBIAN/extrainst_内容
#!/bin/sh
if [[ $1 == upgrade ]]; then
if [ -f "/Library/LaunchDaemons/test.plist" ]; then
if [ ! -d "/usr/lib/TweakInject" ]; then
/bin/launchctl unload /Library/LaunchDaemons/test.plist
/bin/launchctl load /Library/LaunchDaemons/test.plist
else
/bin/launchctl kickstart -k system/test
/bin/launchctl load /Library/LaunchDaemons/test.plist
fi
fi
elif [[ $1 == install ]]; then
if [ -f "/Library/LaunchDaemons/test.plist" ]; then
/bin/launchctl load /Library/LaunchDaemons/test.plist
fi
fi
exit 0
注意control也放到/layout/DEBIAN中
