Linux/Unix commands with examples
Hello guys,
Welcome to
MikeyToTech
If you want
to learn Linux operating system then you should know Linux/Unix commands. If
you are beginner or searching for kali Linux commands for Linux or hacking or
penetration testing then read this post and practice by yourself.
In this post
I have explained Linux/Unix commands with examples. Remember Linux/Unix
commands are case sensitive.
Linux SYSTEM commands
uname
-a :- It displays the all information of
your Linux System.
uname :- It displays the name of your operating system.
uname
-r :- by this command you can know kernel release
information that you are using.
uname
-v :- It displays the kernel version.
uname
-n :- it
displays the node host name. for example if you are using Kali Linux then it
will display kali as node host name, if you changed you system hostname
manually then it will display changed hostname. Here I have changed my system
hostname that’s why uname -n displaying name MikeyToTech.
uname
-m :- it displays information what kind of
machine you are using.
X86_64 means your system is a 64bit
system.
uptime
:- It shows how long this system has
been running(active). It also displays the number of users with running
sessions.
uptime
-p :- It shows only running time of the
system.
uptime
-s :- It show the date/time since when the
system has been running.
hostname :- it shows system host name. (here I have changed
hostname, if you are using kali Linux then it will display kali as host
name)
hostname
-i :- it displays the IP address of the
host.
last
reboot :- It displays reboot history of system.
date :- It displays the current date and time of you system.
date
-u :- It displays the time in GMT(Greenwich
Mean Time)/UTC(Coordinated Universal Time) time zone.
cal :- It prints calendar of current month.
cal -y :- it prints current year calendar.
cal -m
month_name :-
It prints the
calendar for given month_name.
cal month_name year_name :- It prints the calendar for given
month_name and year_name.
w :- It displays who is online, it
displays name of online user.
w -h
:- I displays
name of online user but it don’t display header.
w -i
:- It displays
IP instead of hostname.
whoami
:- It displays
who are logged in as.
finger
user:- It
displays information of user.
DIRECTORY
TRAVERSE
cd :- It is used for go to home
directory.
cd .. :- It is used for go up one level of
the directory.
cd
/dir_name :- It
changes directory to dir_name.
HARDWARE
COMMANDS
dmesg
:- It displays
detected hardware and boot messeges.
cat
/proc/cpuinfo :-
It displays CPU model information.
cat
/proc/meminfo :-
It displays hardware memory information.
lsblk
:- It shows
block devices related information in Linx.
free
-m :- It shows
free and used memory in MB (-m for MB)
lspci
-tv :- It shows
PCI(Peripheral Component Interconnect) devices.
lsusb :- It displays list of USB devices.
dmidecode :- It shows hardware information
from the BIOS(Basic Input Output Device).
hdparm
-i /dev/sda :-
It shows information about disk sda.
hdparm
-tT /dev/sda :-
It do a read speed test on disk sda.
badblocks
-s /dev/sda :-
It tests on unreadable blocks on disk sda.
USERS
command
id :- It displays the active user id with
login and group.
last
:- It displays
last logins on the system.
who :- It shows who is logged in on the
system.
groupadd admin
:- It make group
admin to “admin”.
useradd
MikeyToTech :-
It will add user “MikeyToTech”.
userdel
MikeyToTech :-
It will delete user “MikeyToTech”.
usermod :- It can modify information of
user.
FILE
commands
ls :- It displays list of directories.
ls -a
:- It displays
formatted list of directories. It also displays hidden directories.
ls -l :- It displays list of directories
with it’s permissions.
ls -al :- It displays all information about
files or directories.
pwd :- It displays the path of current directories.
mkdir
directory_name :-
It creates a directory in current directory.
touch
file_name :- It
creates or update, given named file. If given named file is not exists then it
makes new file.
rm
file_name :- It
deletes, given named file from current directory.
rm -r
directory_name :-
It deletes, given named directory recursively.
rm -f
file_name :- It
removes, given named file forcefully from current directory.
rm -rf
directory_name :-
It removes, given named directory forcefully from current directory.
cp
file1 file2 :-
It will copy file1 into file2. It creates file2 if it is not exists.
mv
file1 file2 :-
It will move file1 into file2. It creates file2 if it’s not exists.
Cp -r
directory1 directory2 :- It will copy directory1 into directory2. It makes directory2
if it is not exist.
mv directory1
directory2 :- It
will move directory1 into directory2. It makes directory2 if it is not exist.
mkdir
path :- It will create
directory on given path.
cat
> file :- It
appends input in file.
more
file :- It
displays content of file.
head
file :- It
displays first 10 lines of file.
tail
file :- It
displays last 10 line of file.
gpg -c
file :- It
encrypts, given named file.
gpg
file.gpg :- It
decrypts, given named file.
wc :- It prints the number of bytes,
words and lines in file.
FILE
permissions commands
chmod
octal file_name
:- It changes the permissions of file to octal.
Example:- chmod 777 test.sh
:- It sets rwx permission for owner, group, world.
chmod 755 test.sh :- It sets rwx permission for
owner, rx for group and world.
chmod
+x test.sh :- It
sets executable permission to test.sh file.
chmod
-x test.sh :- It
removes executable permission to test.sh file.
chown
owner_user file
:- It changes the owner(owner user name) of the file.
chown
owner_user_group file :- It changes the owner and group owner (owner user group name) of the
file.
chown
owner_user_owner_group directory :- It changes the owner and group owner of the directory.
PORCESS
RELATED commands
ps :- It displays current active
processes.
ps aux :- It prints all processes owned by
user named ‘x’.
pmap :- It shows memory map of process.
top :- It displays all running
processes.
kill
pid :- It kills
process with mentioned pid id.
killall
proc :- It kills
all processes named proc.
pkill
process_name :-
It sends signal to processes with it’s name.
bg :- It resumes suspended jobs without
bringing them to foreground.
fg :- It brings the most resent job to
foreground.
fg n :- It brings job n to foreground.
NETWORK commands
ifconfig
:- It displays
all netwok interfaces and ip addresses.
ethtool
eth0 :- It is
linux tool to show ethernet status.
mii-tool
eth0 :- It also
show ethernet status.
pint
host :- It sends
echo requests to test internet connection.
whois
domain :- It
displays who is, information for domain.(example : type command ‘whois system_ip).
dig
domain :- It
provides DNS information for domain.
dig -x
domain :- It is
used for reverse lookup host.
hostname
-i :- It is used
for lookup local IP address.
wget
file :- It is
use to download file. (example – type command
wget url it start downloading file from given url).
netstat
-tupi :- It
lists all active listening ports.
COMPRESSION/ARCHIVE
commands
tar xf
file_name.tar :-
It extracts the file from file_name.tar.
tar cf
file.tar directoy_name :- It converts, given name directory int file.tar.
INSTALL/REMOVE
app commands
sudo
Apt install app_name :- It will install app_name app in you linux system.
sudo
Apt remove app_name :- It will remove app_name app from you linux system.
sudo
apt update :- It
will update your linux system.
sudo
apt update app_name :- It will update only app_name app.
SEARCH command
grep
pattern files :-
It searches for pattern in files.
grep
-r pattern dir
:- It searches for pattern in directories.
locate
file :- It finds
all instance of file.
LOGIN
(SSH @ TELNET)
ssh
user@host :- It
connects the host as user.
ssh -p
port user@host
:- It connects the host as user using specific port.
telent
host :- It connects
the system using telnet.
DISK
USAGES
df -h :- It shows free space on mounted
filesystems.
df -i :- It shows free inodes on mounted
filesystem.
fdisk
-l :- It
displays list of disks partitions size and it’s type.
du -sh :- It displays total disk usage on
current directory.
mount device_path mount_point :- It mounts device on mount point.
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