System Information
Hardware Information
Performance Monitoring and Statistics
User Information and Management
File and Directory Commands
Process Management
File Permissions
Networking
Archives ( TAR Files)
Installing Packages
Searching for Information
SSH Login
File Transfer
Disk Usage
Directory Navigation
Misc - ie: open image file from CMD
-- Display Linux system information
uname -a
-- Display kernel release information
uname -r
-- Show which version of redhat installed
cat /etc/redhat-release
-- Show how long the system has been running + load
uptime
-- Show system host name
hostname
-- Display the IP addresses of the host
hostname -I
-- Show system reboot history
last reboot
-- Show the current date and time
date
-- Show this month's calendar
cal
-- Display who is online
w
-- Who you are logged in as
Whoami
2 – HARDWARE INFORMATION
-- Display messages in kernel ring buffer
dmesg
-- Display CPU information
cat /proc/cpuinfo
-- Display memory information
cat /proc/meminfo
-- Display free and used memory ( -h for human readable, -m for MB, -g for GB.)
free -h
-- Display PCI devices
lspci -tv
-- Display USB devices
lsusb -tv
-- Display DMI/SMBIOS (hardware info) from the BIOS
dmidecode
-- Show info about disk sda
hdparm -i /dev/sda
-- Perform a read speed test on disk sda
hdparm -tT /dev/sda
-- Test for unreadable blocks on disk sda
badblocks -s /dev/sda
3 – PERFORMANCE MONITORING AND STATISTICS
-- Display and manage the top processes
top
-- Interactive process viewer (top alternative)
htop
-- Display processor related statistics
mpstat 1
-- Display virtual memory statistics
vmstat 1
-- Display I/O statistics
iostat 1
-- Display the last 100 syslog messages (Use /var/log/syslog for Debian based systems.)
tail 100 /var/log/messages
-- Capture and display all packets on interface eth0
tcpdump -i eth0
-- Monitor all traffic on port 80 ( HTTP )
tcpdump -i eth0 'port 80'
-- List all open files on the system
lsof
-- List files opened by user
lsof -u user
-- Display free and used memory ( -h for human readable, -m for MB, -g for GB.)
free -h
-- Execute "df -h", showing periodic updates
watch df –h
4 – USER INFORMATION AND MANAGEMENT
-- Display the user and group ids of your current user.
id
-- Display the last users who have logged onto the system.
last
-- Show who is logged into the system.
who
-- Show who is logged in and what they are doing.
w
-- Create a group named "test".
groupadd test
-- Create an account named john, with a comment of "John Smith" and create the user's home directory.
useradd -c "John Smith" -m john
-- Delete the john account.
userdel john
-- Add the john account to the sales group
usermod -aG sales john
5 – FILE AND DIRECTORY COMMANDS
-- List all files in a long listing (detailed) format
ls -al
-- Display the present working directory
pwd
-- Create a directory
mkdir directory
-- Remove (delete) file
rm file
-- Remove the directory and its contents recursively
rm -r directory
-- Force removal of file without prompting for confirmation
rm -f file
-- Forcefully remove directory recursively
rm -rf directory
-- Copy file1 to file2
cp file1 file2
-- Copy source_directory recursively to destination. If destination exists, copy source_directory into destination, otherwise create destination with the contents of source_directory.
cp -r source_directory destination
-- Rename or move file1 to file2. If file2 is an existing directory, move file1 into directory file2
mv file1 file2
-- Create symbolic link to linkname
ln -s /path/to/file linkname
-- Create an empty file or update the access and modification times of file.
touch file
-- View the contents of file
cat file
-- Browse through a text file
less file
-- Display the first 10 lines of file
head file
-- Display the last 10 lines of file
tail file
-- Display the last 10 lines of file and "follow" the file as it grows.
tail -f file
6 – PROCESS MANAGEMENT
-- Display your currently running processes
ps
-- Display all the currently running processes on the system.
ps -ef
-- Display process information for processname
ps -ef | grep processname
-- Display and manage the top processes
top
-- Interactive process viewer (top alternative)
htop
-- Kill process with process ID of pid
kill pid
-- Kill all processes named processname
killall processname
-- Start program in the background
program &
-- Display stopped or background jobs
bg
-- Brings the most recent background job to foreground
fg
-- Brings job n to the foreground
fg n
7 – FILE PERMISSIONS
U = User G = Group W = World r = Read w = write x = execute - = no access
8 – NETWORKING
-- Display all network interfaces and ip address
ifconfig -a
-- Display eth0 address and details
ifconfig eth0
-- Query or control network driver and hardware settings
ethtool eth0
-- Send ICMP echo request to host
ping host
-- Display whois information for domain
whois domain
-- Display DNS information for domain
dig domain
-- Reverse lookup of IP_ADDRESS
dig -x IP_ADDRESS
-- Display DNS ip address for domain
host domain
-- Display the network address of the host name.
hostname -i
-- Display all local ip addresses
hostname -I
-- Download http://domain.com/file
-- Display listening tcp and udp ports and corresponding programs
netstat -nutlp
9 – ARCHIVES (TAR FILES)
-- Create tar named archive.tar containing directory.
tar cf archive.tar directory
-- Extract the contents from archive.tar.
tar xf archive.tar
-- Create a gzip compressed tar file name archive.tar.gz.
tar czf archive.tar.gz directory
-- Extract a gzip compressed tar file.
tar xzf archive.tar.gz
-- Create a tar file with bzip2 compression
tar cjf archive.tar.bz2 directory
-- Extract a bzip2 compressed tar file.
tar xjf archive.tar.bz2
10 – INSTALLING PACKAGES
-- Search for a package by keyword.
yum search keyword
-- Install package.
yum install package
-- Display description and summary information about package.
yum info package
-- Install package from local file named package.rpm
rpm -i package.rpm
-- Remove/uninstall package.
yum remove package
-- Install software from source code.
tar zxvf sourcecode.tar.gz
cd sourcecode
./configure
make
make install
11 – SEARCH FOR INFORMATION
-- Search for pattern in file
grep pattern file
-- Search recursively for pattern in directory
grep -r pattern directory
-- Find files and directories by name
locate name
-- Find files in /home/john that start with "prefix".
find /home/john -name 'prefix*'
-- Find files larger than 100MB in /home
find /home -size +100M
12 – SSH LOGINS
-- Connect to host as your local username.
ssh host
-- Connect to host as user
ssh user@host
-- Connect to host using port
ssh -p port user@host
13 – FILE TRANSFERS
-- Secure copy file.txt to the /tmp folder on server
scp file.txt server:/tmp
-- Copy *.html files from server to the local /tmp folder.
scp server:/var/www/*.html /tmp
-- Copy all files and directories recursively from server to the current system's /tmp folder.
scp -r server:/var/www /tmp
-- Synchronize /home to /backups/home
rsync -a /home /backups/
-- Synchronize files/directories between the local and remote system with compression enabled
rsync -avz /home server:/backups/
14 – DISK USAGE
-- Show free and used space on mounted filesystems
df -h
-- Show free and used inodes on mounted filesystems
df -i
-- Display disks partitions sizes and types
fdisk -l
-- Display disk usage for all files and directories in human readable format
du -ah
-- Display total disk usage off the current directory
du –sh
15 – DIRECTORY NAVIGATION
-- To go up one level of the directory tree. (Change into the parent directory.)
cd ..
-- Go to the $HOME directory
cd
-- Change to the /etc directory
cd /etc
16 - Misc
-- Open an image from command line
xdg -open <file name>
eog <file name> (for ubuntu)