Linux has a default mode of operation init 0-6 7
0 means shutdown
1 shows a single-user mode
2 shows a multi-user mode
3 a handoff to a general command line mode service in this mode
4 shows the mode is not used
5 shows a switch to desktop
6 represents restart
linux basic commands
1.chkconfig command is mainly used to update operational level information (start or stop) and query system services
2.ls command to view the current directory information, common parameters -l: view file details, -a: view the current directory of all files, including hidden files .file
3.mkdir to create a directory, cd / home / user / switch to the user directory, mkdir lina create a blank file named lina folder. -P parameter to create a recursive directory, such as mkdir -p / lina / music
4.rm delete files or folders, rm pathname delete files, -r parameter to delete a folder, -f parameter to force the removal, caution must be used with caution in mind, it is best not to use rm -rf
5.tree file directory tree view list
6.chkconfig [--add] [- del] [- list] [System Services] or chkconfig [--level <class code>] [Service System] [on / off / reset] a.
Computer Performance :
1. Scale Cluster: strength in numbers . A load balancing cluster . B high-availability cluster . C High Performance Cluster (application layer) --- the Hadoop cluster = map reduces + HDFS
The basic format of linux command of
command [options] Parameters
* []: On behalf of the brackets, optional; specify a particular function to achieve command
* <>: object code command executed; if not add <> on behalf of not omission must be added to the object.
* Long integer options (not consolidated)
* short integer options (can be combined)
extension (to know): command subcommand [options] Parameters
