Linux System Admin Commands

Linux Server IP Important Commands

hostnamectl command

How to change the Hostname

[root@Sharique ~]# hostnamectl status

Once change the hostname need to restart Linux Server.

[root@Sharique ~]# hostnamectl set-hostname qp

So here you can check the hostname has been changed.

[root@qp ~]# hostnamectl status

[root@qp ~]# hostname

How to change the centos/RedHat Linux  etc/hosts and host IP address.

Now here I am using centos-8 if you will check there is only old version or other Linux difference in directory.

Centos/RedHat Linux

 /etc/sysconfig/network-scripts/ifcfg-eth0

Ubuntu

/etc/netplan/00-installer-config.yaml

[root@qp ~]# vi /etc/sysconfig/network-scripts/ifcfg-ens33

Or

[root@qp ~]# nano /etc/sysconfig/network-scripts/ifcfg-ens33

TYPE=Ethernet
PROXY_METHOD=none
BROWSER_ONLY=no
BOOTPROTO=none
DEFROUTE=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFROUTE=yes
IPV6_FAILURE_FATAL=no
NAME=ens33P96-98f8-48664244bff9
DEVICE=ens33
ONBOOT=yes
IPADDR=192.168.60.49
PREFIX=24
GATEWAY=192.168.60.1
DNS1=192.168.60.2
DOMAIN=querypanel.local
IPV6_PRIVACY=no

After applying the new IP address need to restart the Network.

systemctl start NetworkManager.service

[root@qp ~]# systemctl stop NetworkManager.service

[root@qp ~]# systemctl start NetworkManager.service

[root@qp ~]# systemctl Restart NetworkManager.service

[root@qp ~]# systemctl status NetworkManager.service

Using nmcli Tool

The nmcli is the command-line utility for the managing NetworkManager on CentOS/RHEL 8 Linux system. You can simply use this utility to stop/start network service on your CentOS 8 or RHEL 8 system.

WARNING – Do not run nmcli networking off for the remotely connected systems. This will disable the NetworkManager network connections on the machine and you will lose connection.

[root@qp ~]# sudo nmcli networking off

[root@qp ~]# nmcli general status

[root@qp ~]# nmcli networking on

How do we check mysql and Apache Server Running status.

Here: step by steps methods.

[root@qp ~]# systemctl status httpd

[root@qp ~]# systemctl status httpd.service

[root@qp ~]# systemctl restart httpd

[root@qp ~]# systemctl start httpd

[root@qp ~]# systemctl stop httpd

[root@qp ~]# systemctl status mysqld

[root@qp ~]# systemctl restart mysqld

Command	Function
man	Display information about all commands
uptime	Show how long system is running
users	Show username who are currently logged in
service	Call and execute script
pkill	Kill a process
pmap	Memory map of a process
wget	Download file from network
ftp or sftp	Connect remote ftp host
free	Show memory status
top	Display processor activity of system
last	Display user’s activity in the system
ps	Display about processes running on the system
Shutdown commands	Shutdown and reboot system
info	Display information about given command
env	Display environment variable for currently logged-in user
netstat	Display network status
arp	Check ethernet connectivity and IP address
df	Display filesystem information
du	Display usage
init	Allow to change server bootup
nano	A command line editor
nslookup	Check domain name and IP information
shred	Delete a file by over writing its content
cat	Display, copy or combine text files
pwd>	Print path of current working directory
locate	Finding files by name on system
chown	Change ownership of a file
>alias	To short a command
echo	Display text
cmp	Compare two files byte by byte
mount	Mount a filesystem
ifconfig	Display configuration
traceroute>	Trace existing network
sudo	Run a command as a root user
route	List routing table for your server
ping	Check connection by sending packet test packet
find	Find location of files/directories
users	Show current logged in user
who	Same as w but doesn’t show current process
ls	List all the files
tar	Compress directories
grep	Search for a string in a file
su	Switch from one to another user
awk	Search lines for a given pattern

shariq@unv:~$ man uptime

shariq@unv:~$ man users

shariq@unv:~$ man service

shariq@unv:~$ man pkill

shariq@unv:~$ man pmap