Content of Linux system management and Common commands

The content of Linux system management and Common commands-Linux Enterprise Application-Linux server application information. For details, refer to the following section. Linux system management has a lot of content, which is similar to UNIX systems. In my daily work, I have access to some common system management content and commands, and I will discuss them with my friends.
Start and end the system
1. Start the system
Guided by LILO, read the system running level set in the configuration file/etc/inittab. The levels are classified as follows:
Level content

0 low-level system initialization, power off

1 single user or management level. You can run tasks that may run under multiple tasks, such as detailed disk checks.

2-user mode, but no network support.

3. All functions are enabled.

4 temporarily unavailable

5. log on to Linux using a graphical Terminal

6. restart the system after interruption, sync + reboot

S, S single user status, used for the parameter after the boot name in LILO, can handle the remedy for the loss of the root password.


Run runlevel to view the current running level of the system. telinit changes the init status.
2. Terminate the system
As Linux is a multi-task, multi-user operating system, you should check the current users of the system and their work before termination, and notify them to terminate the operation.
Who lists the logon name, terminal name, and logon time for each current user in the system.
W. query the detailed information of the host
Wall broadcasts notifications to every current user in the system.
Shutdown can be added with parameters for shutdown control
Reboot: Terminate the system and reboot the system.
Halt and poweroff Shutdown
System User Management
Useradd
Userdel remove old account
Modify an existing account using usermod
Groupadd
Remove Old member groups by groupdel
Groupmod modify existing member groups
Passwd Change Password
Chfn modify finger information
Chsh: Modify the login shell
Provides global default values for various commands and files
Configure the corresponding configuration file for different commands and files.
Service Process loaded when ntsysv is started
Set network services such as NFS, SAMBA, and DNS
Testparm checks whether the configuration file of smb. conf is correct.
Smbstatus displays the shared resources currently output by Samba.
Smbclient? L allows you to view the shared resources of a host.
Smbmount and smbumount install and uninstall the shared name of the specified host to the local directory
Ndc Start and Stop DNS Service
Nslookup performs forward DNS resolution and reverse DNS resolution checks
Create a Crontab for regular jobs and Scheduling
Crontab is used to operate the daemon and execution time of each user, create a command list, specify the running time and interval of a command on each line, and cron regularly scans the file to schedule jobs within the required time.
Create a large job running table using batch to run jobs with a low priority, as long as the average system load is less than 1.5
At scheduling a job in a future period
Atq lists jobs in the queue.
Atrm deletes a job in the queue
Backup system and data files
The tar GNU file packaging backup tool creates an archive file and supports Incremental backup. It is the easiest system to use.
Cpio creates an archive file, which can process the length of the file name, and can also handle localized tape errors by skipping errors.
Dump backs up the entire file system and retains change records for Incremental backup.
Handle System security transactions, set up monitoring firewalls, and timely virus detection and removal
Pwconv5 shadow password
Set firewall for ipfwadm and ipchains to build soft routes
Maintain System and other Event Log Files
Syslogd Linux System Log Process
Klogd core log process
Logger shell Interface System Log Module Tool
Check file system integrity
The fsck File System check can only be used by the root user. Check the file size table of the logical file and the disk file, check the number of links between the file and the name, and ensure that the file is correctly delivered, make sure that all idle disk blocks are properly placed in the idle table of the file system.
Create a Linux File System Using mkfs
E2fsck Linux File System check
Mount and umount mount and uninstall the File System
Update online and offline documents
Use RPM to update relevant HOWTO documents.
Disaster recovery
Mkbootdisk
Upgrade and change of software and hardware
RPM is a commonly used software tool for managing and maintaining software installation, upgrade, and deletion.
Hardware configuration tools vary from system to system, but core support is required for the application of a hardware in Linux.
Linux core configuration in linuxconf
Lsmod list current loaded modules
Insmod inserts a module into the active Kernel
Modprobe loads one or more modules and their attachments
Depmod
Rmmod deletes a currently loaded module.
Kerneld core activity Module
Configure the video card for Xconfigurator, XF86Setup, and xf86config
Netcfg
Printtool printer configuration
Configure the sound card for sndcfg
System Performance Monitoring and reasonable resource allocation
Ruptime and uptime provide the average value of System Burden and user information to get an overview of system activities.
Ps display program running statistics
Netstat displays network conditions
Time computing the time taken to execute a command