Understanding the meaning of the Linux operating system daemon

Article Title: understanding the meaning of the Linux operating system daemon. Linux is a technology channel of the IT lab in China. Includes basic categories such as desktop applications, Linux system management, kernel research, embedded systems, and open source.

When a Linux server is started, many system services need to be started. They provide Linux system function interfaces to local and network users and are directly oriented to applications and users. The programs that provide these services are executed by daemons running in the background. A daemon is a process with a long lifetime. They are independent of control terminals and periodically execute a task or wait for some events to be processed. They are often started during system boot loading and terminated when the system is shut down. In linux, there are many daemon processes, and most servers use daemon. At the same time, the daemon completes many system tasks, such as job planning process crond and printing process lqd. Some books and materials also refer to the daemon process as "services ". Select which daemon processes to run based on your needs. View the services of the daemon that can be provided by the system. Run the following command as root:

# Ntsysv

The window shown in interface 1 describes the functions of various system services in detail. In alphabetical order:

1. Introduction to the Linux daemon

1. alsasound: the Alsa audio card driver daemon. The Alsa sound card driver was originally written for a sound card Gravis UltraSound (GUS). The program was proven to be excellent, so the author began to write drivers for a general sound card. Alsa is compatible with OSS/Free and OSS/Linux, but it has its own access port, which is even better than OSS.

2. acpid: acpid (Advanced Configuration and Power Interface) is a new Power management standard to replace the traditional APM Power management standard. Generally, the laptop needs to be powered on for management.

3. atalk: AppleTalk network daemon. Do not run the program in the background. The data structure of the program must be initialized for a certain period of time before other processes are run.

4. amd: automatically installs the NFS daemon.

5. anacron: An automated task daemon. Red Hat Linux tool with four automated tasks: cron, anacron, at, and batc. When your Linux server is not running all day long, this anacron can help you execute the work that has not been executed within the time set by "crontab.

6. apmd: apmd (Advanced Power Management) is Advanced Power Management. Traditional Power Management Standards are useful for laptops and can be used to understand the battery information of the system. And write the relevant information into the log through syslogd. It can also be used to shut down when the power supply is insufficient.

7. arptables_jf: Specifies the daemon for user control of the arptables network.

8. arpwatch: records logs and constructs an ethernet address and IP address pair database seen on the LAN interface.

Atd: The at and batch command daemon processes. You can use the at command to schedule tasks. Batch is used to run Batch processing tasks when the system load is low.

9. autofs: automatically installs the management process automount, which is related to NFS and depends on the NIS server.

10. bootparamd: boot parameter server that provides information required for booting a diskless workstation on the LAN.

11. ch: the Bluetooth server daemon process.

12. crond: cron is a traditional Unix program that periodically runs user-scheduled tasks. Compared with the traditional Unix version, the Linux version adds many attributes, which are safer and easier to configure. Similar to scheduled tasks.

13. chargen: the chargen server using the tcp Protocol. Character Generator Protocol is a network service. Its main function is to provide a function similar to remote typing.

14. chargen-udp: Use the chargen server of UDP protocol.

15. cpuspeed: monitor the idle percentage of the system to reduce or speed up the CPU clock speed and voltage so as to minimize the energy consumption when the system is idle, while maximizing the system execution speed when the system is busy.

16. dhcpd: service daemon of the Dynamic Host Control Protocol.

17. cups: cups (Common UNIX Printing System) is a Common UNIX print daemon and provides the third-generation Printing function for Linux.

18. cups-config-daemons: the cups printing system switches the daemon process.

19. cups-lpd: the daemon for printing cups rows.

20. daytime: the Daytime daemon of TCP protocol is used to obtain the date and time from the remote server for the client. Default port: 13.

21. daytime-udp: Use the Daytime daemon of UDP protocol.

22. dc_server: the proxy server daemon that uses the SSL secure socket.

23. dc_client: the client daemon that uses the SSL secure socket.

24. diskdump: the server disk backup daemon.

25. echo: the server displays the customer data service daemon.

26. echo-udp: the server that uses the UDP protocol returns the client data service daemon.

27. eklogin: a service daemon that accepts rlogin session authentication and is encrypted with kerberos5.

28. gated: Gateway Routing daemon. It supports various routing protocols, including RIP version 1 and 2, dcn hello protocol, OSPF version 2, and EGP version 2 to 4.

29. gpm: the gpm (General Purpose Mouse Daemon) Daemon provides Mouse support for Linux programs in text mode, such as mc (Midnight Commander. It also supports the copy and paste operations and pop-up menus on the console.

30. gssftp: ftp daemon using kerberos 5 Authentication

31. httpd: the Apache daemon of the Web server. It can be used to provide HTML files and CGI dynamic content services.

32. inetd: Internet operation daemon. The monitoring network needs various services managed by it, and starts corresponding service programs when necessary. It is replaced by xinetd in Redhat and Mandrake linux. Debian, Slackware, and SuSE are still used.

33. innd: Usenet news server daemon.

34. iiim: the daemon process of the Chinese Input Method server.

35. iptables: iptables firewall daemon.

36. irda: infrared port daemon.

37. isdn: start and stop the service daemon process.

38. krb5-telnet: telnet Daemon using kerberos 5 authentication.

39. klogin: log on to the daemon remotely.

40. keytable: the function of this process is to reprinted the keyboard ing table defined in/etc/sysconfig/keyboards. This table can be selected using the kbdconfig tool. You should make the program active.

41. irqbalance: the Server Load balancer daemon for system interrupt requests in multiple system processor environments. If you only install one CPU, you do not need to load this daemon.

42. kshell: kshell daemon.

43. kudzu: The hardware automatic detection program automatically checks whether the hardware has changed and adds or deletes the hardware accordingly. When the system starts, kudzu checks the current hardware and compares it with the hardware information stored in/etc/sysconfig/hwconf, if a hardware is added or deleted from the system, kudzu will detect it and notify the user whether to configure it, And then modify etc/sysconfig/hwconf, synchronize hardware data with the system. If the/etc/sysconfig/hwconf file does not exist, kudzu will start from/etc/modprobe. conf,/etc/sysconfig/network-scripts/and etc/X11/XF86Config to detect existing hardware. If you do not want to add new hardware, you can close the startup service to speed up the system startup time.

44. ldap: ldap (Lightweight Directory Access Protocol) Directory Access Protocol server daemon process.

45. lm_seroems: detects the working process of the motherboard.

46. lpd: lpd is an old-fashioned print daemon that submits lpr and other programs to print jobs.

47. mdmonitor: the daemon of RAID-related devices.

48. messagebus: The D-BUS is a library that provides one-to-one communication for two or more applications. Dbus-daemon-1 is an application that uses this library to implement the messagebus daemon. Multiple applications can exchange information with other programs by connecting to the messagebus daemon.

49. microcode_ctl: encodes and sends new microcodes to the kernel to update the Intel IA32 series processor daemon.

50. mysqld: a fast, efficient, and reliable lightweight SQL database engine daemon process.

51. named: DNS (BIND) server daemon.

52. netplugd: The netplugd (network cable hotplug management daemon) daemon is used to monitor the status of one or more network interfaces and run an external script program when some events are triggered.

53. netdump: Remote network backup server daemon.

54. netfs: Network Filesystem Mounter. This process installs and uninstalls NFS, SAMBA, and NCP Network file systems.

55. nfs: Network File System daemon.

56. nfslock: NFS is a popular protocol for sharing files through TCP/IP networks. This daemon provides the NFS file locking function.

57. ntpd: Network time Protocol daemon (Network time correction Protocol ). Ntpd is a protocol daemon process used to synchronize time between the system and a precise time source.

58. network: enable/disable the network interface daemon at startup.

59. psacct: the daemon includes several tools used to monitor process activity, including ac, lastcomm, accton, and sa.

60. pcmcia: it is mainly used to support the daemon process of the laptop interface.

61. portmap: This daemon is used to support RPC connections. RPC is used for NFS, NIS, and other services.

62. postgresql: PostgreSQL relational database engine.

63. proftpd: proftpd is a dedicated ftp server daemon in Unix.

64. pppoe: ADSL connection daemon.

65. random: a high-quality random number generator for saving and restoring the system. These random numbers are provided by Uniform random behaviors.

66. rawdevices: used to load the daemon of raw devices when using the cluster file system.

67. readahead, readahead_early: readahead and readahead_early are two backend daemon programs launched in Fedora core 2. The function is to read the files used to start the system to the memory during system startup, and then execute the files in the memory to speed up the system startup.

68. rhnsd: Red Hat Network Service daemon. Notify the official security information and patch the system.

69. routed: This daemon supports the automatic IP route table maintenance of the RIP Protocol. RIP is mainly used on small networks. A larger network requires a more complex protocol.

70. rsync: remote sync remote Data Backup daemon.

71. rsh: Start a shell on the remote host and execute USER commands.

72. rwhod: allows remote users to obtain a list of all logged-on users on the machines running the rwho daemon.

73. rstatd: A waiting process for other machines on the LAN to collect and provide system information.

74. ruserd: remote user location service, an RPC-based service that provides user information about a machine log currently recorded on the LAN

75. rwalld: activates the rpc. rwall service process. This is an RPC-based service that allows users to write messages to each terminal registered on the LAN machine.

76. rwhod: activates the rwhod service process. It supports rwho and ruptime services of the LAN.

77. saslauthd: Use the SASL authentication daemon.

78. sendmail: the sendmail daemon of the mail server.

79. smb: Samba file sharing/printing service daemon.

80. snmpd: The local Simple Network Management daemon.

81. squid: the squid daemon of the proxy server.

82. sshd: OpenSSH server daemon. Secure Shell Protocol enables Secure remote host management.

83. smartd: Self Monitor Analysis and Reporting Technology System, which monitors whether your hard disk is faulty.

84. syslog: a script that enables syslog and klogd system logs to wait for processes during system boot.

85. time: the daemon obtains the time and date from the remote host and uses the TCP protocol.

86. time-udp: This daemon obtains the time and date from the remote host and uses UDP protocol.

87. tux: run the daemon of the apache server in the Linux kernel.

88. vsftpd: the daemon of the vsftpd server.

89. vncserver: VNC (Virtual Network Computing, Virtual Network Computing), which provides a lightweight protocol for displaying the entire desktop of a remote computer on a local system.

90. xfs: X Window server daemon, which provides a font set for local and remote X servers.

91. xinetd: supports core daemon processes of multiple network services.

92. ypbind: activates the ypbind service process for the NIS (Network Information System) client.

93. yppasswdd: the NIS Password server daemon.

94. ypserv: the NIS master server daemon.

95. yum: automatically upgrades the RPM operating system and manages the software package daemon.

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