(Linux Command Line) Part 1 – Linux Commands for Server Management and Monitoring

Linux is an open-source Operating System, typically used on servers because it is high stable, secured and free. Linux is primarily based on Command Lines (Linux Commands), similar to the previous Microsoft DOS. Linux server administration is quite complicated, it requires certain knowledge and experiences.

Serial Linux Commands:

  >> Part 1 – Linux Commands for Server Management and Monitoring
  >> Part 2 – Linux Commands for File and Folder/ Directory Management
  >> Part 3 – Linux Commands for File Editor in Linux (CentOS, Ubuntu)
  >> Part 4 – Linux Commands for Network Configuration in Linux (CentOS, Ubuntu)
  >> Part 5 – Other Useful Linux Commands (CentOS, Ubuntu) you need to know

In this serial articles of Linux Commands, I will summarize and classify all the useful Linux Command Lines into groups so that you can easily understand and use. There are many ways we can connect to a Linux Server via SSH from a terminal (to perform a Command Line), you can use Putty, OpenSSH …

Linux Commands for Server Management and Monitoring

Linux server administration includes many tasks, such as: System Monitor (CPU status, memory status, processes…), service management, user management, user roles (create users, change passwords, permission …), reset server, run tasks or schedule task …

Below tables are the most important Command Line you need to know to start managing a Linux Server. Most command lines apply to both Ubuntu and CentOS

1. System information

COMMAND	PURPOSE / DESCRIPTION
cat /proc/cpuinfo	Check CPU information (number of core, family, vendor, clock speed…)
cat /proc/meminfo	Check RAM usage status – used by each process/ service
cat /proc/version	Check Linux Kernel version
cat /proc/ioports	Check I/O port information
cat /etc/redhat-release	Check Centos (and other Redhat) version
uname -a	Check Kernel information
free -m	Check memory (RAM and SWAP) usage status – summary
init 0	Shuttown the server (similar to shutdown -h now or telinit 0)
df -h	Display system files and disk usage status
du -sh	Display the capacity of the current folder/ directory
du -ah	Display the capacity of sub-folders and files in the current folder
du -h –max-depth=1	Display the capacity of direct child sub-folders in the current folder
df	Display the capacity of hard disks and all its partitions
lspci	Display the mainboard information
/sbin/ifconfig	Display the IP configuration of the server
hostname	Display the hostname of the server
finger [email protected]	Collect details about the current user
arch	Check server’s architech
cat /proc/swaps	Check SWAP information (SWAP in Linux is very similar to Virtual RAM in Windows)
last reboot	Check reboot history of the server

2. Linux Commands to shutdown, restart… Linux server

COMMAND	PURPOSE / DESCRIPTION
logout	Kill the current session
reboot	Restart the server
shutdown -r now	Restart the server (similar to the command reboot)
shutdown -h now	Shutdown the server immediately
shutdown -h 9:30	Shedule for shutting down the server (the server will shutdown at 9:30)
shutdown -c	Cancel all scheduled shutdown commands
telinit 0	Turn off the server (similar to the command shutdown -h now)
init 0	Turn off the server (similar to the command shutdown -h now ortelinit 0)
exit	Exit the current terminal window
halt	Turn off the server (similar the command shutdown)
sleep	Pause/Sleep the system (similar to Sleep in Windows)

3. Linux Commands for User management in Linux (CentOS, Ubuntu)

COMMAND	PURPOSE / DESCRIPTION
passwd	Change password (standard user can only change his password, while  root user can change the password of any user)
pwck	Check the syntax and data format of user/password (/etc/passwd)
useradd	Create a new user, eg: useradd -c “New user 1” -g Group1
userdel	Delete a user
usermod	Change/ Edit/ Modify user information (group, user name…)
groupadd	Create a new group (group user)
groupdel	Delete a group
groupmod	Modify/ Edit group information, eg: groupmod -n “old group name”  “new group name”
who /w	Display all logged in users in the system
uname	Display system name (host)
id	Display user id (user identification number)
logname	Display current logged in user name
su	Login the system with other user (similar to Secondary Logon feature in Windows)
groups	Display all groups that the current user belongs to
#vi /etc/passwd	Display list users
#vi /etc/group	Display list groups
chmod [file,folder]	Set permission for file/ folder (only the file/ folder owner can perform this command)
chown user [file, folder]	Set/ Change the owner for file/ folder
chgrp group [filefolder]	Set/ Change the owner-group for file/ folder

4. Linux Commands for Service and Process management in Linux (CentOS, Ubuntu)

COMMAND	PURPOSE / DESCRIPTION
top	Similar to Task Manager in Windows, it will display all the information/ status of the system resource (processes, services, average load). Command top -d will allow you to set a refresh duration
ps -u username	Display processes performed by a user
ps -U root	Display all processes except system processes
ps –A	Display all running processes
ss	Display all connecting/ open sockets
ss -l	Display all open ports
w username	Check the logged in user, login history, processes running by this user
vmstat 3	Control behaviors of the system, hardware and system information
ps	Displays all the current running program
uptime	Display the uptime and load average of the system
rpm	Check, uninstall or install a .RPM package
yum	Install a packaged program (like rpm)
wget	Download from a URL
sh	Run an .SH program
startx	Start xwindows mode from a terminal window
yum update –y	Update Linux (CentOS)
stop/start/restart	Stop/ Start or Restart a service or a program, eg: service mysql stop or /etc/init.d/mysqld start
kill	Kill a proccess (the super-user can kill all processes, standard users can kill only processes run by the user)
kill PID or %job	Stop/ Kill a process by the ID (Process Identification Number) or job number
pstree	Display all processes in a process-tree
service –status-all	Check all the service status
whereis mysql	Display the location that the service is installed (eg: MySQL)
service –status-all |     grep abc	Check the status of a particular process
kill -9 PID	Force close a process by process ID
kill -1 PID	Force close a process ID then re-load the default config of the process

5. Other Usefull Linux Commands for Server Management

COMMAND	PURPOSE / DESCRIPTION
clear	Clear the command window (similar CLS in MS-DOS)
hwclock	Fix BIOS calendar
cal	Display system calendar
date	Display date, time of the system
date –s “27 SEP 2011 14:26:00”	Set system date-time by a string
date +%Y%m%d -s “20130318″	Set system date by a string (time does not change)
date +%T -s “00:29:00″	Set system time by a string (date does not change)

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Source: https://easytipz.com/computer-tips/linux-command-line-part-1-commands-line-for-server-management-and-monitoring/