Linux Commands For A Beginner [Updated]

These are the most commonly used Linux commands for a beginner or a newbie. This may help out someone who is trying to quickly learn some basic commands in Linux world. All the best!

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Purpose	Commands
View/List Files/Folders	“ls” OR “ll” “ls -ali” (view all including hidden files) “ls -ld” (view only folders) “ls -Zl” (view SELinux context along with file attributes)
Copy Files/Folders	“cp” {cp <Options> <Source> <Destination>}
Secure Copy	“scp” {scp <User@Host:SourcePath> <User@Host:DestinationPath>} - Check manual page of SCP for further options.
Move Files/Folders	“mv” {mv <Options> <Source> <Destination>}
Create a New File	“touch <Filename>” {creates an empty file} OR “vi <Filename> {allows editing new file}
Create a Directory	“mkdir <DirectoryName>” OR “mkdir -p <PathOfTheDirectory>” {this would create all the directories/sub-directories in the given path if not available}
View a File	“cat” # cat <FileName>
Change Directory	“cd <DirectoryName>” {directory name could be an absolute path} “cd -" {to switch to the previous directory} “cd ~” {to go to user home directory} “cd ..” {to go back to parent directory OR scroll up in the directory list}
Print Current Working Directory	“pwd”
Delete a File/Folder	“rm <File/FolderName>” “rm -rf <File/FolderName>” {this would wipe out a file/folder and doesn’t prompt for confirmation}
Check File Type	“file” {file <File/FolderName> }
Change File/Folder Permissions	“chmod” Eg:# chmod o+w /testfile (sets write permission for this file for other users) OR # chmod 646 /testfile
Change File/Folder Ownership	“chown” Eg:# chown redhat /testfile (changes file owner as redhat user) Eg:# chown redhat:redhat /testfile (changes owner and group to redhat user for this file)
View File Special Attributes	"lsattr"
Set File Special Attributes	“chattr” Eg:# chattr +i /testfile (this would not allow file deletion even by root user)  # chattr -i /testfile (this removes “immutable flag” set on the file)
View ACL attributes (Access Control List)	“getfacl <File/FolderName>”
Set ACL attributes (Access Control List)	“setfacl -m u:<Username>:<Permissions> <File/FolderPath>” Ex: # setfacl -m u:testuser:rw /etc/fstab
Check Kernel Version	“uname” {# uname -a Or # uname -r}
Check Red Hat Release Version	# cat /etc/redhat-release OR # cat /etc/os-release
Check OS Architecture	# arch Or # uname -m
List of PCI Devices Found	# lspci
List of USB Devices Found	# lsusb
List of Hard Drives Found	“fdisk” {# fdisk -l} OR “parted” {# parted --list}
Get Processors Details	“lscpu” OR # cat /proc/cpuinfo OR # dmidecode --type processor
Get Memory Modules Details	# dmidecode --type memory
List HAL Devices Found	# lshal
List Block Devices Found	“lsblk” # lsblk -f (this would show up block devices along with file system)
List Swap Device	# swapon -s OR # cat /proc/swaps
Check RAM(Random Access Memory)	“free” {# free -m Or # free -g = display in Megabytes/Gigabytes format} OR # cat /proc/meminfo
List Modules Loaded	# lsmod
List Mounted Devices	“mount” (# mount) OR # cat /proc/mounts OR # cat /etc/mtab OR “df” (# df -h)
Check File System Usage	# df -Th
Check/Display Hostname	# hostname # hostname -f {this would show-up the Fully Qualified Domain Name} OR # sysctl -n kernel.hostname # cat /etc/hostname { RHEL7 & above }
Check System Uptime	# uptime
Check SELinux Status (Security Enhanced Linux)	# sestatus OR # cat /etc/sysconfig/selinux # cat /etc/selinux/config { RHEL7 & above }
Find The IP Address	“ifconfig” {# ifconfig -a} OR # ip a
Find Current User Logged-in	# who -s OR # whoami
Check Current Date & Time	# date
Switch User	“su”
Shutdown Command	# shutdown -h now OR # poweroff OR # halt OR # init 0 # systemctl poweroff { RHEL7 & above }
Reboot Command	# shutdown -r now OR # reboot OR # init 6 # systemctl reboot { RHEL7 & above }
Check Current Runlevel	# runlevel OR # who -r # systemctl get-default { RHEL7 & above }
Switch from Runlevel 3 (text mode) to Runlevel 5 (GUI Mode) { In RHEL7, it is targets not runlevel }	# init 5 OR # startx # systemctl set-default graphical.target { RHEL7 & above } # systemctl isolate graphical.target
Switch from Runlevel 5 to Runlevel 3	# init 3 # systemctl set-default multi-user.target { RHEL7 & above } # systemctl isolate multi-user.target
Create a Partition on a Hard Drive	Using “fdisk” or “parted” command
Create ext4 File System	# mkfs.ext4 <DeviceName> OR # mke2fs -t ext4 <DeviceName>
Create ext3 File System	# mkfs.ext3 <DeviceName> OR # mke2fs -t ext3 <DeviceName>
Check File System for Errors {recommended to un-mount file system before running this command}	# e2fsck -f -y <DeviceName> {-f =force, -y =set automatic answer Yes}
Check if Network Interface is Up {I’ve taken first network interface “eth0” into reference here}	# ping localhost OR # ethtool eth0 {check for “Link Detected”} OR # ifconfig eth0 {check for “UP” in the fourth line} OR # ip addr show eth0 { RHEL7 & above } OR # ip a s eth0
List out Running Processes	# ps aux OR # ps -ef OR # top
Search for a file	# locate <FileName> # find <PathWhereToSearch> -name <FileName> -type f Eg:# find / -name hello.txt -type f {this would search for the file “hello.txt” under the / (root) directory}
Search for a word in a file	“grep” # grep -i <Word> <FileName> {this would search for the “word” within “FileName” regardless of case}
View top 10 lines in a file	“head” # head <FileName>
View bottom 10 lines in a file	“tail” # tail <FileName>
Check All the Daemons/Services Running	# service --status-all # systemctl list-units --type service --all { RHEL7 & above }
List Services Started in Run-level 5	# chkconfig --list | grep “5:on” # chkconfig --list {This would list out all the services/daemons running and their status in each run level} # chkconfig --list |grep “3:on” {this would list out all the services which are running on run-level 3}  # systemctl list-units --type service  { RHEL7 & above }

NOTE: These are a few basic commands commonly used, there would be a many alternatives available, to get complete syntax help check out the “man” pages of a command.