RedHat/CentOs

1. IDB-BISEW
MD. SHIHAB HOSSAIN
A simple keyboard shortcuts layout
1. [Ctrl] + [Alt] + [Backspace] = kills your current X session.
2. [Ctrl] + [Alt] + [Delete] = From a non-graphical shell prompt, shuts down your Red Hat
Enterprise Linux system.
3. [Ctrl] + [Alt] + [Fn] = switches screens. [Ctrl]+[Alt] + one of the function keys displays
an available screen. By default, [F1] through [F6] are text-mode shell prompt screens and
[F7] is the graphical desktop screen.
4. [Alt] + [Tab] = switches tasks in a graphical desktop environment.
5. [Ctrl] + [a] = moves cursor to the beginning of a line.
6. [Ctrl] + [d] = logout of (and close) shell prompt. [Ctrl] + [e] = moves cursor to end of a
line. This works in most text editors and in the URL field in Mozilla.
7. [Ctrl] + [l] = clears the terminal
8.
9. [Ctrl] + [u] = clears the current line.
a. .
10. [Middle Mouse Button] = pastes highlighted text.
11. [Tab] = command autocomplete
12. [Up] and [Down] Arrow = shows command history.
13. clear = clears the shell prompt screen. Type this command to clear all visible data from
the shell prompt screen.
14. exit = logout. Type this at a shell prompt to logout of the current user or root account.
15. history = shows history of commands. Type this at a shell prompt to see a numbered
list of the previous 1000 commands you typed. To display a shorter list of previously
used commands, type history followed by a space and a number. For example, history
20.
16. reset = refreshes the shell prompt screen. Type this at a shell prompt to refresh the
screen if characters are unclear or appear corrupt.
17. head = showing first 10 lines
18. tail= showing last 10 lines
19. E s c + = copy the last argument of the previous command
20. C t r l + k= Clear from the cursor to the end
21. C t r l + L e f t A r row= Jump to the beginning ofthe previous word

2. IDB-BISEW
MD. SHIHAB HOSSAIN
Starting terminal
Application  utilities  terminal
Empty desktop right click terminal
Changing hostname
Hostnamectl set-hostname ‘’desired name’’
Command Basic
Command Option argument
Usermod -l shihab
Set local language
[root@host ~]# localctl set-locale LANG=fr_FR.utf8
yum langavailable
yum langinstall code
BashShell
[student@despktopX ~]# Super user interface
[student@despktopX ~]$ Regular user interface

3. IDB-BISEW
MD. SHIHAB HOSSAIN
Changing Password and status
passwd
location: file / e t c / passwd
word count
wc = for counting word
Example: wc /etc/passwd
History = for getting command history
Time and date
Example: timedatectl set-time 22:31:14
timedatectl set-timezone America/New_York
Manpage= for Manual
Man –k= for specific keyword
PWD= for getting information of present working directory
cd= for changing directory
cd..= for parent directory directly

4. IDB-BISEW
MD. SHIHAB HOSSAIN
touch= for creating file instantly
ll= for listing desired information
ls –al= for listing the current location with hidden file
cp= for copy
mv= for move/rename
rm= for remove
mkdir=making directory
cp –r= copy directory
rm –r = removing directory
grep= for specific topic query(Ex: grep “model name” /proc/cpuinfo will give
cpuinfo instantly)

5. IDB-BISEW
MD. SHIHAB HOSSAIN
vim= for editing text ( I for insert, v for visualmode, esc for initial mode, wq/x for
saveand quit)
gedit= For graphicaltext editing
nano= used also for editing text
pinfo= To view the file information
tar = for archiving files and folder (-c for create, -x for extract), rm –rf
‘’foldername’’ for deleting zipped
id= for getting user id
ps= for process information
uid= for getting uid number
su= for switching user
useradd= to add user
usermod= to modify user account (Ex: usermod -l shihab for lock user) –u for
unlock
groupadd= to add group
groupmod= to modify group (-n for new name, -g for GID)
groupdel= for deleting group
Password aging
Chage(-d for minimum days forcing password login,-lfor listing the currentuser
settings, -E for expired days)
Sudo= for delegating user with specific access)
File permission
r= read
w= write
x= execute
drwxr= directory read write and execute permission has been assigned
chmod=changing permission( u,g,o,a for ‘who’ +/- remarks add/remove permission,
rwx for ‘which’)

6. IDB-BISEW
MD. SHIHAB HOSSAIN
chown= to change the userownership (ex: chown - R student foodir)
umask= for masking or unmasking the user permission by using value.( 0 for will not musk, 007 for
other permission)
kill= forkillingprocess.(ex: kill pidforkillingspecificprocessid) killall=forkillingall processwithPID
uptime= for systemuptime information
top= runninggraphical interface
systemd= systemstartupand serverprocessmanger
systemctl=Query the state of all units to verify a system startup.(Ex: systemctl --type=service)
(Ex: systemctl is - active sshd will show particular active unit - all will show all active and inactive)
Daemon
We should add ‘’d’’ after any service for daemon
EX: sudo systemctl is - enabled sshd
Mask/unmask= Masking will create a link in the configuration directories so that if the service is
started nothing will happen.
EX: systemctl mask network systemctl unmask network
ssh= for establishing remote connection
(EX: ssh 192.168.10.10 ssh remoteuser@)remotehost hostname)
systemctl restart sshd= for restarting only ssh service
ssh-keygen= for creating ssh service private key

7. IDB-BISEW
MD. SHIHAB HOSSAIN
IP addresses
Ip addr show eth0= For getting assigned ip address on the Ethernet
ping
netstat
ip route
traceroute
‘’nmcli’’ for networking
nmcli con show= showing connection status
nmcli con show –active= showing active connection
nmcli dev status= for getting device status
nmcli dev show eth0 = specific device status
nmcli con add con - name " default " type ethernet ifname eth0= add a connection profile
nmcli con add con - name " static " ifname eth0 autoconnect no type= assigning ip address
ethernet ip4 172.25.X.10/24 gw4 172.25.X.254
nmcli con up eth0= turning on the connection profile
nmcli con reload= for reloading present connection
getent
getent hosts hostname= for testing host name resolution
yum
For updating, installing software and related repository packages

8. IDB-BISEW
MD. SHIHAB HOSSAIN