wpa_supplicant源码剖析-main.c解析

这里记录了 wpa_supplicant 的命令行用法

static void usage(void)
{int i;printf("%s\n\n%s\n""usage:\n""  wpa_supplicant [-BddhKLqq"
#ifdef CONFIG_DEBUG_SYSLOG"s"
#endif /* CONFIG_DEBUG_SYSLOG */"t"
#ifdef CONFIG_CTRL_IFACE_DBUS_NEW"u"
#endif /* CONFIG_CTRL_IFACE_DBUS_NEW */"vW] [-P<pid file>] ""[-g<global ctrl>] \\\n""        [-G<group>] \\\n""        -i<ifname> -c<config file> [-C<ctrl>] [-D<driver>] ""[-p<driver_param>] \\\n""        [-b<br_ifname>] [-e<entropy file>]"
#ifdef CONFIG_DEBUG_FILE" [-f<debug file>]"
#endif /* CONFIG_DEBUG_FILE */" \\\n""        [-o<override driver>] [-O<override ctrl>] \\\n""        [-N -i<ifname> -c<conf> [-C<ctrl>] ""[-D<driver>] \\\n"
#ifdef CONFIG_P2P"        [-m<P2P Device config file>] \\\n"
#endif /* CONFIG_P2P */"        [-p<driver_param>] [-b<br_ifname>] [-I<config file>] ""...]\n""\n""drivers:\n",wpa_supplicant_version, wpa_supplicant_license);for (i = 0; wpa_drivers[i]; i++) {printf("  %s = %s\n",wpa_drivers[i]->name,wpa_drivers[i]->desc);}#ifndef CONFIG_NO_STDOUT_DEBUGprintf("options:\n""  -b = optional bridge interface name\n""  -B = run daemon in the background\n""  -c = Configuration file\n""  -C = ctrl_interface parameter (only used if -c is not)\n""  -d = increase debugging verbosity (-dd even more)\n""  -D = driver name (can be multiple drivers: nl80211,wext)\n""  -e = entropy file\n"
#ifdef CONFIG_DEBUG_FILE"  -f = log output to debug file instead of stdout\n"
#endif /* CONFIG_DEBUG_FILE */"  -g = global ctrl_interface\n""  -G = global ctrl_interface group\n""  -h = show this help text\n""  -i = interface name\n""  -I = additional configuration file\n""  -K = include keys (passwords, etc.) in debug output\n""  -L = show license (BSD)\n"
#ifdef CONFIG_P2P"  -m = Configuration file for the P2P Device interface\n"
#endif /* CONFIG_P2P */
#ifdef CONFIG_MATCH_IFACE"  -M = start describing new matching interface\n"
#endif /* CONFIG_MATCH_IFACE */"  -N = start describing new interface\n""  -o = override driver parameter for new interfaces\n""  -O = override ctrl_interface parameter for new interfaces\n""  -p = driver parameters\n""  -P = PID file\n""  -q = decrease debugging verbosity (-qq even less)\n"
#ifdef CONFIG_DEBUG_SYSLOG"  -s = log output to syslog instead of stdout\n"
#endif /* CONFIG_DEBUG_SYSLOG */"  -t = include timestamp in debug messages\n"
#ifdef CONFIG_DEBUG_LINUX_TRACING"  -T = record to Linux tracing in addition to logging\n""       (records all messages regardless of debug verbosity)\n"
#endif /* CONFIG_DEBUG_LINUX_TRACING */
#ifdef CONFIG_CTRL_IFACE_DBUS_NEW"  -u = enable DBus control interface\n"
#endif /* CONFIG_CTRL_IFACE_DBUS_NEW */"  -v = show version\n""  -W = wait for a control interface monitor before starting\n");printf("example:\n""  wpa_supplicant -D%s -iwlan0 -c/etc/wpa_supplicant.conf\n",wpa_drivers[0] ? wpa_drivers[0]->name : "nl80211");
#endif /* CONFIG_NO_STDOUT_DEBUG */
}

这里会将 0,1,2 文件描述符指向/dev/null，相当于关闭标准输入，标准输出，标准错误