# Linux
### Linux Commands List
The commands found in the downloadable cheat sheet are listed below.
#### Hardware Information
Show **bootup messages**:
```
dmesg
```
See **CPU information**:
```
cat /proc/cpuinfo
```
Display **free and used memory** with:
```
free -h
```
List **hardware configuration** information:
```
lshw
```
See information about **block devices**:
```
lsblk
```
Show **PCI devices** in a tree-like diagram:
```
lspci -tv
```
Display **USB devices** in a tree-like diagram:
```
lsusb -tv
```
Show **hardware information** from the BIOS:
```
dmidecode
```
Display **disk data** information:
```
hdparm -i /dev/disk
```
Conduct a **read-speed test** on device/disk:
```
hdparm -tT /dev/[device]
```
Test for **unreadable blocks** on device/disk:
```
badblocks -s /dev/[device]
```
#### Searching
[Search for a specific pattern](https://phoenixnap.com/kb/grep-multiple-strings) in a file with [grep](https://phoenixnap.com/kb/grep-command-linux-unix-examples):
```
grep [pattern] [file_name]
```
**Recursively search for a pattern** in a directory:
```
grep -r [pattern] [directory_name]
```
Find all **files and directories related to a particular name**:
```
locate [name]
```
List names that **begin with a specified character** **`[a]`** in a specified location **`[/folder/location]`** by using the [**`find`** command](https://phoenixnap.com/kb/guide-linux-find-command):
```
find [/folder/location] -name [a]
```
See **files larger than a specified size** **`[+100M]`** in a folder:
```
find [/folder/location] -size [+100M]
```
**Note:** Some commands are not recommended to use. Learn about them in our list of [dangerous Linux commands](https://phoenixnap.com/kb/dangerous-linux-terminal-commands).
#### File Commands
**List files** in the directory:
```
ls
```
**List all files** ([shows hidden files](https://phoenixnap.com/kb/show-hidden-files-linux)):
```
ls -a
```
**Show directory** you are currently working in:
```
pwd
```
[Create a new directory](https://phoenixnap.com/kb/create-directory-linux-mkdir-command):
```
mkdir [directory]
```
[Remove a file](https://phoenixnap.com/kb/how-to-remove-files-directories-linux-command-line):
```
rm [file_name]
```
**Remove a directory** recursively:
```
rm -r [directory_name]
```
**Recursively remove a directory** without requiring confirmation:
```
rm -rf [directory_name]
```
[Copy the contents of one file](https://phoenixnap.com/kb/how-to-copy-files-directories-linux) to another file:
```
cp [file_name1] [file_name2]
```
**Recursively copy the contents of one file** to a second file:
```
cp -r [directory_name1] [directory_name2]
```
**Rename** **`[file_name1]`** to **`[file_name2]`** with the command:
```
mv [file_name1] [file_name2]
```
[Create a symbolic link](https://phoenixnap.com/kb/symbolic-link-linux) to a file:
```
ln -s /path/to/[file_name] [link_name]
```
Create a **new file** using [touch](https://phoenixnap.com/kb/touch-command-in-linux):
```
touch [file_name]
```
**Show the contents** of a file:
```
more [file_name]
```
or use the [**`cat`** command](https://phoenixnap.com/kb/linux-cat-command):
```
cat [file_name]
```
Append file contents to another file:
```
cat [file_name1] >> [file_name2]
```
Display the **first 10 lines** of a file with:
```
head [file_name]
```
Show the **last 10 lines** of a file:
```
tail [file_name]
```
**Encrypt** a file:
```
gpg -c [file_name]
```
**Decrypt** a file:
```
gpg [file_name.gpg]
```
Show the **number of words, lines, and bytes** in a file:
```
wc
```
**Note:** Want to read more about file creation? Check out an article about [how to create a file in Linux using the command line](https://phoenixnap.com/kb/how-to-create-a-file-in-linux).
#### Directory Navigation
Move **up one level** in the directory tree structure:
```
cd ..
```
Change **directory to** **`$HOME`**:
```
cd
```
**Change location** to a specified directory:
```
cd /chosen/directory
```
#### File Compression
**Archive an existing file**:
```
tar cf [compressed_file.tar] [file_name]
```
[Extract an archived file](https://phoenixnap.com/kb/extract-tar-gz-files-linux-command-line#htoc-using-tar-utility):
```
tar xf [compressed_file.tar]
```
Create a **gzip compressed tar file** by running:
```
tar czf [compressed_file.tar.gz]
```
**Compress** a file with the **`.gz`** extension:
```
gzip [file_name]
```
**Note:** For a more comprehensive overview of how to use **`tar`** refer to our guide [tar Command in Linux With Examples](https://phoenixnap.com/kb/tar-command-in-linux).
#### File Transfer
[Copy a file to a server](https://phoenixnap.com/kb/how-to-use-linux-scp-command-examples) directory securely:
```
scp [file_name.txt] [server/tmp]
```
**Synchronize** the contents of a directory **with a backup directory** using the [rsync command](https://phoenixnap.com/kb/rsync-command-linux-examples):
```
rsync -a [/your/directory] [/backup/]
```
#### Users
See details about the **active users**:
```
id
```
Show **last system logins**:
```
last
```
Display who is **currently logged into the system** with the [who command](https://phoenixnap.com/kb/linux-who-command):
```
who
```
Show which users are **logged in** and **their activity**:
```
w
```
**Add a new group** by typing:
```
groupadd [group_name]
```
Add a **new user**:
```
adduser [user_name]
```
Add a **user to a group**:
```
usermod -aG [group_name] [user_name]
```
Temporarily **elevate user privileges** to superuser or root using the [sudo command](https://phoenixnap.com/kb/linux-sudo-command):
```
sudo [command_to_be_executed_as_superuser]
```
**Delete** a user:
```
userdel [user_name]
```
**Modify** user information with:
```
usermod
```
**Note:** If you want to learn more about users and groups, take a look at our article on [how to add a user to a group in Linux](https://phoenixnap.com/kb/how-to-add-user-to-group-linux).
#### Package Installation
[List all installed package](https://phoenixnap.com/kb/how-to-list-installed-packages-on-centos)s with **`yum`**:
```
yum list installed
```
Find a package by a **related keyword**:
```
yum search [keyword]
```
Show **package information and summary**:
```
yum info [package_name]
```
Install a package using the **YUM package manager**:
```
yum install [package_name.rpm]
```
Install a package using the **DNF package manager**:
```
dnf install [package_name.rpm]
```
Install a package[ using the **APT package manager**](https://phoenixnap.com/kb/how-to-use-apt-get-commands):
```
apt-get install [package_name]
```
**Install** an **`.rpm`** package from a local file:
```
rpm -i [package_name.rpm]
```
**Remove** an **`.rpm`** package:
```
rpm -e [package_name.rpm]
```
Install software from **source code**:
```
tar zxvf [source_code.tar.gz]
cd [source_code]
./configure
make
make install
```
#### Process Related
See a **snapshot of active processes**:
```
ps
```
Show **processes in a tree-like diagram**:
```
pstree
```
Display a **memory usage map** of processes:
```
pmap
```
See **all running processes**:
```
top
```
[Terminate a Linux process](https://phoenixnap.com/kb/how-to-kill-a-process-in-linux) under a **given ID**:
```
kill [process_id]
```
Terminate a process under a **specific name**:
```
pkill [proc_name]
```
Terminate all processes **labelled** **"proc”**:
```
killall [proc_name]
```
**List and resume stopped jobs** in the background:
```
bg
```
Bring the most **recently suspended job to the** **foreground**:
```
fg
```
Bring a **particular job to the** **foreground**:
```
fg [job]
```
List **files opened by running processes**:
```
lsof
```
**Note:** If you want to learn more about shell jobs, how to terminate jobs or keep them running after you log off, check out our article on [how to use disown command](https://phoenixnap.com/kb/disown-command-linux).
#### System Information
Show **system information**:
```
uname -r
```
See [kernel release information](https://phoenixnap.com/kb/check-linux-kernel-version):
```
uname -a
```
Display **how long the system has been running**, including load average:
```
uptime
```
See system **hostname**:
```
hostname
```
Show the **IP address** of the system:
```
hostname -i
```
List system **reboot history**:
```
last reboot
```
See current **time and date**:
```
date
```
Query and **change the system clock** with:
```
timedatectl
```
Show current **calendar** (month and day):
```
cal
```
List **logged in users**:
```
w
```
See which **user you are using**:
```
whoami
```
Show **information about a particular user**:
```
finger [username]
```
#### Disk Usage
You can use the df and du commands to [check disk space in Linux](https://phoenixnap.com/kb/linux-check-disk-space).
See **free and used space** on mounted systems:
```
df -h
```
Show **free inodes** on mounted filesystems:
```
df -i
```
Display **disk partitions, sizes, and types** with the command:
```
fdisk -l
```
See [**disk usage** for all files and directory](https://phoenixnap.com/kb/show-linux-directory-size):
```
du -ah
```
Show **disk usage of the directory** you are currently in:
```
du -sh
```
Display **target mount point** for all filesystem:
```
findmnt
```
**Mount a device**:
```
mount [device_path] [mount_point]
```
#### SSH Login
**Connect to host** as user:
```
ssh user@host
```
Securely **connect to host via SSH** default port 22:
```
ssh host
```
Connect to host **using a particular port**:
```
ssh -p [port] user@host
```
Connect to host **via telnet default port 23**:
```
telnet host
```
**Note**: For a detailed explanation of SSH Linux Commands, refer to our [19 Common SSH Commands in Linux](https://phoenixnap.com/kb/linux-ssh-commands) tutorial.
#### File Permission
[Chown command in Linux](https://phoenixnap.com/kb/linux-chown-command-with-examples) changes file and directory ownership.
Assign **read, write, and execute permission** to everyone:
```
chmod 777 [file_name]
```
Give **read, write, and execute permission to owner**, and r**ead and execute permission to group and others**:
```
chmod 755 [file_name]
```
Assign **full permission to owner**, and **read and write permission to group and others**:
```
chmod 766 [file_name]
```
Change the **ownership of a file**:
```
chown [user] [file_name]
```
Change the **owner and group ownership of a file**:
```
chown [user]:[group] [file_name]
```
**Note**: To learn more about how to check and change permissions, refer to our [Linux File Permission Tutorial](https://phoenixnap.com/kb/linux-file-permissions).
#### Network
[List IP addresses ](https://phoenixnap.com/kb/linux-ip-command-examples)and **network interfaces**:
```
ip addr show
```
Assign an **IP address to interface eth0**:
```
ip address add [IP_address]
```
Display **IP addresses of all network interfaces** with:
```
ifconfig
```
See **active (listening) ports** with the [netstat command](https://phoenixnap.com/kb/netstat-command):
```
netstat -pnltu
```
Show **tcp** and **udp** **ports** and their programs:
```
netstat -nutlp
```
Display more **information about a domain**:
```
whois [domain]
```
Show **DNS information** about a domain using the [dig command](https://phoenixnap.com/kb/linux-dig-command-examples):
```
dig [domain]
```
Do a **reverse lookup** **on domain**:
```
dig -x host
```
Do **reverse lookup of an IP address**:
```
dig -x [ip_address]
```
Perform an **IP lookup for a domain**:
```
host [domain]
```
Show the **local IP address**:
```
hostname -I
```
**Download a file** from a domain using the [**`wget`** command](https://phoenixnap.com/kb/wget-command-with-examples):
```
wget [file_name]
```
#### Linux Keyboard Shortcuts
**Kill process** running in the terminal:
```
Ctrl + C
```
Stop **current process**:
```
Ctrl + Z
```
The process can be **resumed** in the **foreground** with **`fg`** or in the **background** with **`bg`**.
Cut **one word before the cursor** and add it to clipboard:
```
Ctrl + W
```
Cut **part of the line before the cursor** and add it to clipboard:
```
Ctrl + U
```
Cut **part of the line after the cursor** and add it to clipboard:
```
Ctrl + K
```
**Paste** from clipboard:
```
Ctrl + Y
```
**Recall last command** that matches the provided characters:
```
Ctrl + R
```
**Run** the previously recalled command:
```
Ctrl + O
```
**Exit command history** without running a command:
```
Ctrl + G
```
**Run the last command** again:
```
!!
```
**Log out** of current session:
```
exit
```
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