All Linux-Commands with description
System Commands
$ uname –a - display linux system information
$ uname –r - display kernel release information
$ uptime - show how long system running + load
$ hostname - show system host name
$ hostname -i - display the IP address of the host
$ last reboot - show system reboot history
$ date - show the current date and time
$ cal - show this month calendar
$ w - display who is online
$ whoami - who you are logged in as
$ finger user - display information about user
Hardware related
$ dmesg - detected hardware and boot messages
$ cat /proc/cpuinfo - CPU model
$ cat /proc/meminfo - hardware memory
$ cat /proc/interrupts - lists the number of interrupts per CPU per I/O device
$ lshw - displays information on hardware configuration of the system
$ lsblk - displays block device related information in Linux
$ free -m - used and free memory (-m for MB)
$ lspci -tv - show PCI devices
$ lsusb -tv - show USB devices
$ lshal - show a list of all devices with their properties
$ dmidecode - show hardware info from the BIOS
$ hdparm -i /dev/sda -show info about disk sda
$ hdparm -tT /dev/sda - do a read speed test on disk sda
$ badblocks -s /dev/sda - test for unreadable blocks on disk sda
Statistics and Analyze
$ top - display and update the top cpu processes
$ mpstat 1 - display processors related statistics
$ vmstat 2 - display virtual memory statistics
$ iostat 2 - display I/O statistics (2sec Intervals)
$ tail -n 500 /var/log/syslog - last 10 kernel/syslog messages
$ tcpdump -i eth1 - capture all packets flows on interface eth1
$ tcpdump -i eth0 'port 80' - monitor all traffic on port 80 ( HTTP )
$ lsof - list all open files belonging to all active processes
$ lsof -u testuser - list files opened by specific user
$ free –m - show amount of RAM
$ watch df –h - watch changeable data continuously
Users
$ id - show the active user id with login and group
$ last - show last logins on the system
$ who - show who is logged on the system
$ groupadd admin - add group "admin" (force add existing group)
$ useradd -c "Joe Smith" -g admin -m joe - Create user "joe" and add to group "admin"
$ userdel joe - delete user joe (force,file removal)
$ adduser joe - add user "joe"
$ usermod - modify user information
File Commands
$ ls –al - display all information about files / directories
$ ls -alR - display all information about files / directories recursively
$ pwd - show current directory path
$ mkdir directory-name - create a directory
$ rm file-name - delete file
$ rm -r directory-name - delete directory recursively
$ rm -f file-name - forcefully remove file
$ rm -rf directory-name - forcefully remove directory recursively
$ cp file1 file2 - copy file1 to file2
$ cp -r dir1 dir2 - copy dir1 to dir2, create dir2 if it doesn’t exist
$ mv file1 file2 - move files from one place to another
$ ln –s /path/to/file-name link-name - create symbolic link to file-name
$ touch file - create or update file
$ cat > file - place standard input into file
$ more file - output the contents of file
$ head file - output the first 10 lines of file
$ tail file - output the last 10 lines of file
$ tail -f file - output the contents of file as it grows starting with the last 10 lines
$ gpg -c file - encrypt file
$ gpg file.gpg - decrypt file
Process Related
$ ps - display your currently active processes
$ ps aux | grep 'telnet' - find all process id related to telnet process
$ pmap - memory map of process
$ top - display all running processes
$ kill pid - kill process with mentioned pid id
$ killall proc - kill all processes named proc
$ pkill processname - send signal to a process with its name
$ bg - resumes suspended jobs without bringing them to foreground
$ fg - brings the most recent job to foreground
$ fg n - brings job n to the foreground
File Permission Related
$ chmod octal file-name - change the permissions of file to octal , which can be found separately for user, group and world; octal value 4 -read 2 –write 1 –execute
$ chown owner-user file - change owner of the file
$ chown owner-user:owner-group file-name - change owner and group owner of the file
$ chown owner-user:owner-group directory - change owner and group owner of the directory
Network
$ ifconfig –a - display all network ports and ip address
$ ifconfig eth1 mtu 9000 up - set mtu to 9000
$ ifconfig eth0 - display specific ethernet port ip address and details
$ ifconfig -a | grep HWaddr - display MAC address
change MAC address:
# ifconfig eth0 down
# ifconfig eth0 hw ether 00:80:48:BA:d1:30
# ifconfig eth0 up
$ ip addr show - display all network interfaces and ip address (available in iproute2 package,powerful than ifconfig)
$ ip address add 192.168.0.1 dev eth0 - set ip address
$ ethtool eth0 - linux tool to show ethernet status (set full duplex , pause parameter)
$ mii-tool eth0 - linux tool to show ethernet status (more or like ethtool)
$ ping host - send echo request to test connection (learn sing enhanced ping tool)
$ whois domain - get who is information for domain
$ dig domain - get DNS information for domain (screenshots with other available parameters)
$ dig -x host - reverse lookup host
$ host google.com - lookup DNS ip address for the name
$ hostname –i - lookup local ip address (set hostname too)
$ wget file - download file (very useful other option)
$ netstat -tupl - listing all active listening ports(tcp,udp,pid)
WiFi related:
$ iwconfig wlan0 essid "mynetworkESSID" - specify ESSID for the WLAN
$ dhclient wlan0 - to receive an IP address, netmask, DNS server and default gateway from the Access Point
$ iwconfig wlan0 mode managed key [WEP key] - 128 bit WEP use 26 hex characters, 64 bit WEP uses 10
$ iwconfig wlan0 mode master - set the card to act as an access point mode
$ iwconfig wlan0 mode managed - set card to client mode on a network with an access point
$ iwconfig wlan0 mode ad-hoc - set card to peer to peer networking or no access point mode
$ iwconfig wlan0 mode monitor - set card to RFMON mode
$ iwconfig wlan0 essid any - with some cards you may disable the ESSID checking
$ iwconfig wlan0 key 1111-1111-1111-1111 - set 128 bit WEP key
$ iwconfig wlan0 key off - disable WEP key
$ iwconfig wlan0 key open - sets open mode, no authentication is used and card may accept non-encrypted sessions
$ iwlist wlan0 scan - give the list of Access Points and Ad-Hoc cells in range (ESSID, Quality, Frequency, Mode etc.)
$ iwlist wlan0 power - list the various Power Management attributes and modes of the device
$ iwlist wlan0 txpower - list the various Transmit Power available on the device
$ iwlist wlan0 retry - list the transmit retry limits and retry lifetime on the device
Compression / Archives
$ tar cf test.tar test - create tar named test.tar containing test/
$ tar xf test.tar - extract the files from test.tar
$ tar czf test.tar.gz test - create a tar with gzip compression
$ gzip test - compress file and renames it to test.gz
Install Package
$ rpm -i pkgname.rpm - install rpm based package
$ rpm -e pkgname - remove package
Install from source
$ ./configure
$ make
$ make install
$ apt-get update - re-synchronize the package index files from their sources
$ apt-get upgrade - install the newest versions of all packages currently installed on the system from the sources
$ apt-get install package - install package
$ apt-get remove package - remove package
$ apt-cache search package - search for package
Search
$ grep pattern files - search for pattern in files
$ grep -r pattern dir - search recursively for pattern in dir
$ locate file - find all instances of file
$ find /home/tom -name 'index*' - find files names that start with "index"
$ find /home -size +10000k - find files larger than 10000k in /home
Login (ssh and telnet)
$ ssh user@host - connect to host as user
$ ssh -p port user@host - connect to host using specific port
$ telnet host - connect to the system using telnet port
File transfer
scp
$ scp file.txt server2:/tmp - secure copy file.txt to remote host /tmp folder
$ scp gordon@server2:/www/*.html /www/tmp - copy *.html files from remote host to current system /www/tmp folder
$ scp -r gordon@server2:/www /www/tmp - copy all files and folders recursively from remote server to the current system /www/tmp folder
rsync
$ rsync -a /home/apps /backup/ - synchronize source to destination
$ rsync -avz /home/apps gordon@192.168.10.1:/backup - synchronize files/directories between the local and remote system with compression enabled
Disk Usage
$ df –h - show free space on mounted filesystems
$ df -i - show free inodes on mounted filesystems
$ fdisk -l - show disks partitions sizes and types
$ du -ah - display disk usage in human readable form
$ findmnt - displays target mount point for all filesystem
$ mount device-path mount-point - mount a device
Directory
$ cd .. - go up one level of the directory tree
$ cd - go to $HOME directory
$ cd /test - change to /test directory
Keyboard shortcuts
Alt+Ctrl+T - open Terminal Window
Alt+Ctrl+L - lock the screen
Alt+Ctrl+Del - logoff
Alt+F4 - close current window
Alt+F2 - pop up command window (for quickly running commands)
Super-W - show all windows in the current workspace
Ctrl+Super+D - show desktop
Ctrl+A - select all items on list or text
Ctrl+C - copy all selected items to clipboard
Ctrl+X - cut all selected items to clipboard
Ctrl+V or Mouse middle button click - paste all selected items to clipboard
PrintScr - takes screenshot
Alt+PrintScr - takes screenshot of windows
Shift+PrintScr - takes screenshot of selected window area
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