Processes Running After Boot Up

Date: 2015-01-31

To Compile this reference:

  1. Plugged in the Yun into the USB on my laptop. Logged in. Started YunSerialTerminal. Rebooted.
  2. Watched the reboot process via the YunSerialTerminal.
  3. When completed, I ssh'd into the Yun.
  4. ran ps w > ps-w
  5. ran just ps > ps

The raw dumps of ps-w & ps.

The first 30 (or so) items in the process table are kernel process (the ones in square brackets). They are beyond the scope of this writing.

PID #1 is 'init' which is the mother of all process. From there until PID # 575, all the processes are kernel related. This leaves about 20 or so processes to document.

NOTE on references: Where possible, the utility is linked to Wikipedia, a Linux reference, the OpenWrt reference page, the Busybox reference page, and at times the later two. As a reference, it is also good to know about the OpenWrt HOWTOs Page.

PID
Process filename
Description
573
/etc/init.d/rcS
rc apparently means run command. The S (upper case) is for Start. This process does the boot process and launches many of the programs we see in this table.
575
logger
logger(1) - a shell command interface to the syslog(3) system log module
576
init
init - boot process management daemon
617
[cfg80211]
kernel module for wireless
699
/sbin/syslogd
syslogd - a Busybox utility - system logging utilities
701
/sbin/klogd
klogd - Kernel Log Daemon
703
/sbin/hotplug2
hotplug2 - is a system for managing devices that can be dynamically attached to and removed from the system while it's running.
713
/sbin/ubusd
ubusd - interface for other daemons to register themselves as well as sending messages.
736
/sbin/netifd
netifd - Netifd (Network Interface Daemon) reference
799
udhcpc
udhcpc - a Busybox utility - a very small DHCP client. THIS FOR THE ETHERNET.
1222
wpa_supplicant
wpa_supplicant - is support for the wireless security protocols WPA and WPA2 (IEEE 802.11i / RSN)
1295
/sbin/watchdog
watchdog - a Busybox utility stated as: Periodically write to watchdog device DEV.

THIS IS PART of HOTPLUG.

The reboot default is 60 seconds, with the reset default at 30 seconds.

Yun reset is every 5 seconds.

1301
udhcpc
udhcpc - a Busybox utility - a very small DHCP client. THIS FOR THE WIFI.
1409
/usr/sbin/dropbear
dropbear - an SSH server
1416
/usr/sbin/uhttpd
uhttpd - a webserver written from scratch by OpenWrt/LuCI developers.
1425
/usr/sbin/dbus-daemon
dbus-daemon - a system messaging system ala IPC
1446
/usr/sbin/dnsmasq
dnsmasq - a DNS forwarder and DHCP server
1452
avahi-daemon: running [Arduino.local]
a mDNS daemon that provides zeroconf (zero configuration) service.
1455
/usr/sbin/thd
triggerhappy a daemon service for (HID) hardware buttons
1479
/usr/sbin/ntpd
ntpd - a Busybox utility - a NTP (Network Time Protocol) server. Beside Busybox other utilities are available.
1486
{uSDaemon} /bin/sh /sbin/uSDaemon
uSDaemon - a daemon to automatically discover the presence of a SD.
1554
/usr/sbin/dropbear
dropbear - an SSH server - the instance that logged me in.