Linux empty files and other useful instructions summary _linux

1). > filename

2).:> filename

3. echo "" > filename (file size truncated to 1 bytes)

4). echo > FileName

5). cat/dev/null > FileName

6). cp/dev/null filename

Cat A.log >> b.log add content from a append to B

Cat A.log > B.log writes the contents of A to B and covers the contents of B Central

View newest logfile:tail-f logfile

View all installed packages packages for the system: dpkg-query-l

Viewing services for System sniffing

# NETSTAT-LN

If you need to see all the processes currently running on your system, you need to use the following command:

# PS AUXW

service[Service Name] Perform action

Options and Parameters:

To perform an action: the work to be done by a service (Start|stop|status|restart ...)

--status-all: Display all of the system's self-boot services

Format: Service <service>

Print command line usage Help for the specified service <service>.

Format: Service <service> start

Start the specified system service <service>

Format: Service <service> stop

Stop the specified system service <service>

Format: Service <service> restart

Restarts the specified system service <service>, stopping (stop) before starting (start).

format: Chkconfig--list

View the list of system services and the level of operation for each service.

format: Chkconfig <service> on

Sets the specified service <service> starts automatically when it is powered on.

format: chkconfig <service> off

Sets the specified service <service> does not start automatically when the machine is open.

It can be divided into 2 categories according to how the service is started:

Self-initiated services: Most of the services that will be started when powered on. Each service has a process to control

Unified Control Start Service: A separate process is responsible for starting these services, as to when the user control is initiated. This independent process is xinetd.

The Unified control boot service is also a self starter service, but its controlled service does not necessarily boot on

A few important catalogs

/etc/init.d/: All service startup Script Repository (Learn shell script syntax good place)
/etc/sysconfig/(Initialization environment profile for each service)
/etc/xined.conf Unified Control Start service overall configuration file
/etc/xined.d/Unified Control Start service profile (profile for each service)
/etc/: Self-starting service individual profiles
/var/lib/the respective profiles of the self-boot service
/var/run/: PID records for each service's program

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