Linux Services

Description The Common UNIX Printing System ("CUPS") is a cross-platform printing solution for all UNIX environments. It is based on the "Internet Printing Protocol" and provides complete printing services to most PostScript and raster printers. CUPS is a replacement for the LPD printing system. It replaces the lpr command with its own and the LPD printer drivers with its own versions. However, CUPS is similar to LPD in that it uses PostScript as its underlying language for page … [Read more...] about Linux OS Service ‘cups’

This is a script which configures kdump (kernel dump). Kdump provides a memory dump into a file named vmcore when the kernel has a critical issue. Vmcore is often required to investigate the issue. The crash dump is captured from the context of a freshly-booted kernel, not from the context of the crashed kernel. Kdump uses kexec to boot into a second kernel whenever the system crashes. Kexec is a fast-boot mechanism which allows rebooting a new Linux kernel from the context of a running kernel … [Read more...] about Linux OS Service ‘kdump’

Description The Linux Hardware Abstraction Layer (HAL) implements a coherent description of all the hardware on a system, including hot-plugged devices such as on USB (Universal Serial Bus). It works by merging information presented by the operating system, the physical hardware, device drivers, subsystems such as CUPS (Common Unix Printing System), and even from system administrators. This information is collated and made available to application programs via a HAL programming … [Read more...] about Linux OS Service ‘haldaemon’

The portreserve program aims to help services with well-known ports that lie in the portmap range. It prevents portmap from a real service's port by occupying it itself, until the real service tells it to release the port (generally in the init script). For example the cups package provides /etc/portreserve/cups. # cat /etc/portreserve/cups ipp In /etc/services, it is defined "service-name ipp" is equal to 631 ports. When portreserve service starts, portreserve reserves 631 ports. # … [Read more...] about Linux OS Service ‘portreserve’

Service Name kudzu Description This executes kudzu, the automatic hardware detection tool developed by Red Hat. "kudzu" detects and configures new and/or changed hardware on a system. It loads the required drivers and unloads redundant drivers. It is configured by default to run at system boot time to determine what hardware has been added or removed from the system. First, it compares hardware detected against information in /etc/sysconfig/hwconf (if it exists). Then it determines … [Read more...] about Linux OS Service ‘kudzu’

Service Name lm_sensors Description The lm_sensors is a service, set up to monitor hardware like CPU temperature or fan speed. Not all system hardware provides the necessary sensor hardware resource for the lm_sensors service to be useful. Later lm_sensor packages include the sensors_detect utility, which can be used to probe which sensors your hardware provides and which drivers you need. lm_sensors drivers include two groups: Bus drivers are provided for the I2C(Inter … [Read more...] about Linux OS Service ‘lm_sensors’

SELinux (Security Enhanced Linux) provides mandatory access control to the Linux operating system. SELinux is quite pervasive, even if only in PERMISSIVE mode. This can expose latent bugs in non-SELinux components that are not visible unless SELinux is running. Frustrated users have developed the perception that SELinux is difficult to use. The setroubleshoot service is intended to make SELinux more friendly. It collects SELinux audit events from the kernel and runs a series of analysis … [Read more...] about Linux OS Service ‘setroubleshoot’

The psacct service is responsible for starting and stopping process accounting at system boot time and at system shutdown. This service is a wrapper that invokes the action accounting control program. Service Control To obtain the psacct service, install the psacct RPM package: # yum install psacct To manage the psacct service for automated service start and stop, use the chkconfig tool: # chkconfig psacct on # chkconfig --list psacct psacct 0:off 1:off 2:on 3:on 4:on 5:on 6:off # … [Read more...] about Linux OS Service ‘psacct’

The NetworkManager daemon attempts to keep an active network connection available at all times. The NetworkManager facility offers a tool called NetworkManagerDispatcher which executes commands in /etc/NetworkManager/dispatcher.d according to the changing state of the network interfaces. All scripts in this directory are invoked for every state change of any network interface; the scripts must decide whether to process the event. The companion service NetworkManager must be running to … [Read more...] about Linux OS Service ‘NetworkManagerDispatcher’

The yum-updatesd daemon regularly checks the yum repository and provides notification of updates available for your system. Notifications can be made via syslog, email or dbus, a communication method used between applications. When configured to connect a yum repository, the daemon calls the "yum update" command to update packages on the system. The yum-updatesd service (/etc/init.d/yum-updatesd) is provided by the yum-updatesd package. When started, the service calls /usr/sbin/yum-updatesd, a … [Read more...] about Linux OS Service ‘yum-updatesd’