Команды Linux для пользователей Linux, которые хотят изучить Linux

$ uname –a => Display linux system information $ uname –r => Display kernel release information $ cat /etc/redhat_release => Show which version of redhat installed $ 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

$ 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 $ 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

$ 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 $ tail -n 500 /var/log/messages => 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 $ 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

$ 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(real user who logged in) $ groupadd admin => Add group "admin" (force add existing group) $ useradd -c "Sam Tomshi" -g admin -m sam => Create user "sam" and add to group "admin" $ userdel sam => Delete user sam (force,file removal) $ adduser sam => Add user "sam" $ usermod => Modify user information(mostly useful for linux system admins)

$ ls –al => Display all information about files/ directories $ pwd => Show current directory path $ mkdir directory-name => Create a directory $ rm file-name => Delete file(be careful of using rm command) $ 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 (timestamp change) $ 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

$ ps # Display your currently active processes $ ps aux | grep 'telnet' # Find all process id related to telnet process $ pmap # Memory map of process (kernel,user memory etc) $ top # Display all running processes $ kill pid # Kill process with mentioned pid id (types of signals) $ 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 (bg and fg command) $ fg # Brings the most recent job to foreground $ fg n # Brings job n to the foreground

$ ls -al => Display all information about files/ directories $ pwd => Show current directory path(simple but need every day) $ mkdir directory-name => Create a directory(create mutiple directory) $ rm file-name => Delete file(be careful of using rm command) $ 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

$ ifconfig –a # Display all network ports and ip address (set mtu and other all options,ifconfig now in deprecated network command) $ ifconfig eth0 # Display specific ethernet port ip address and details $ 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 (8 examples of host command) $ 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) (13 examples) 

$ tar cf home.tar home # Create tar named home.tar containing home/ (11 tar examples) $ tar xf file.tar # Extract the files from file.tar $ tar czf file.tar.gz files # Create a tar with gzip compression $ gzip file # Compress file and renames it to file.gz (untar gzip file)

$ rpm -i pkgname.rpm # Install rpm based package (Installing, Uninstalling, Updating, Querying ,Verifying) $ rpm -e pkgname # Remove package Install from source ./configure make make install (what it is)

$ grep pattern files # Search for pattern in files (you will this command often) $ 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"(10 find examples) $ find /home -size +10000k # Find files larger than 10000k in /home

$ ssh user@host # Connect to host as user (secure data communication command) $ ssh -p port user@host # Connect to host using specific port $ telnet host # Connect to the system using telnet port

**scp** $ scp file.txt server2:/tmp # Secure copy file.txt to remote host /tmp folder $ scp nixsavy@server2:/www/*.html /www/tmp # Copy *.html files from remote host to current system /www/tmp folder $ scp -r nixsavy@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 [email protected]:/backup # Synchronize files/directories between the local and remote system with compression enabled

$ df –h # Show free space on mounted filesystems(commonly used command) $ df -i # Show free inodes on mounted filesystems $ fdisk -l # Show disks partitions sizes and types(fdisk command output) $ du -ah # Display disk usage in human readable form (command variations) $ du -sh # Display total disk usage on the current directory $ findmnt # Displays target mount point for all filesystem (refer type,list,evaluate output) $ mount device-path mount-point # Mount a device 

$ cd .. # To go up one level of the directory tree(simple & most needed) $ cd # Go to $HOME directory $ cd /test # Change to /test directory