Basic Linux TutorialIntroduction – What is it? Why to learn? Linux installation directory structures Boot process Run levels in Linux Desktop Environments Different shells BASH Internal and External Commands Basic Linux Commands Important files and directories in Linux Environmental and Shell Variables Command history in Linux Character classes in Linux Text editors vim nano Searching files Creating new files Viewing File Contents File commands File permissions and ownership WildCards (Globbing) in files File compression Directory commands xargs command in Linux Comparing files Searching patterns using grep command Translating the characters using tr command Extracting data using cut command Stream editing using sed command Data extraction and reporting using awk command Sorting the file or string input uniq command in Linux Difference between grep, tr, cut, sed and awk commands Hardware commands Hard disk and memory space commands Working with Processes Managing Jobs Working with cron jobs Service command in Linux Network commands Managing Users and Groups Other Popular commands Standard streams and Redirection Pipes Package Managers in Linux
Network commands in linux shellNetwork commands are very helpful in getting information on network interfaces, IP addresses, physical addresses, network connections, domain look up and troubleshooting network issues. Here is the list of network commands in Linux.
curl command in Linuxcurl command allows you to work with applications using HTTP, FTP, FTPS, HTTPS, SCP, SFTP, TFTP, TELNET, DICT, LDAP, LDAPS, FILE, POP3, IMAP, SMTP, RTMP and RTSP protocols. For example – If you want to download any file from the web server, you can use below command.
If curl is not installed on your Ubuntu machine, you can install it using below command.
$ curl www.softpost.org
Here is the list of curl commands.
$ sudo apt-get install curl
$ curl www.softpost.org -> This command will download the home page of www.softpost.org and display it on standard output. $ curl -o index.html www.softpost.org -> If you want to save the file instead of viewing it on console, you can use -o option and provide the file name where you want to save downloaded file. Here -o stands for output. $ curl -O www.example.com/example.html -> If you want to save the downloaded file with same name as url, you can use -O option. $ curl https://securesite.com/login.html $ curl –insecure https://self-signed-cert.com/login.html
wget command in Linuxwget command is just like curl. Main difference is that wget command supports only HTTP, HTTPS and FTP protocols. Also curl is more widely used than wget. wget can get the urls recursively. Here is the list of wget commands.
$ wget www.softpost.org -> This command will download the home page of www.softpost.org and display it on standard output. $ wget -o index.html www.softpost.org -> If you want to save the file instead of viewing it on console, you can use -o option and provide the file name where you want to save downloaded file. Here -o stands for output. $ wget ‐‐input url-list.txt -> This command can be used to download multiple urls specified in url-list.txt file.
ping command in Linuxping command is used to check the connection with other host
ping command sends the packets to given host indefinitely. If you want to restrict the packets to be sent to the host, you can use below command. Here ping command will send only 4 packets to host.
$ ping <host-name>
$ ping -c 4 <host-name>
ifconfig command in Linuxifconfig command shows the ip address and physical address of each network interface on the host.
Below image shows the sample output of ifconfig command. The number next to HWaddr is the physical address of network interface. The number next to inet addr is the IP address of network interface.
$ ifconfig -a
hostname command in Linux
To change the name of your system, you will have to use below command.
$ hostname # This command can be used to print or set system name.
Also note that changes are temporary. To make the changes permanent, you will have to edit /etc/hostname file with the new host name.
$ hostname <new-host-name>
dig/host/nslookup command in Linuxdig command is used for getting DNS information of domain name
Here is the sample output of dig command.host and nslookup commands also provide similar information.
$ dig www.softpost.org
traceroute command in Linuxtraceroute command is used to trace the route to Host.
If this command is not available in your Ubuntu system, you can use below command to install it.
$ traceroute www.softpost.org
$ sudo apt-get install traceroute
netstat command in Linuxnetstat stands for network statistics. This command shows all network connections as well as network interface information. To know about all tcp and udp connections, you can use below command. Here -t stands for TCP connection. -u stands for UDP connections.
You can use below command to know all network connections on your system.
$ netstat -tu
$ netstat -a
lsof command in LinuxBelow command can be used to display the list of all open files including the ones used by network connections.
To list only TCP and UDP connections, you can use below commands
$ sudo lsof
$ lsof -i tcp
To list processes listening on specific port say 80, you can use below command.
$ lsof -i udp
lsof -i :80
ftp command in Linuxftp command allows you to upload, download, manage files on FTP server To connect to any server, type below command.
Once the connection is established, you will have to enter user id and password. Once you log in successfully, you can issue below commands.
$ ftp <server-name>
- put filename – Upload a file to the server
- get filename – Download a file from the server
- mput *.txt – Put multiple files ending with .txt on the server
- mget *.txt – Get multiple files ending with .txt from the server
- ls – Get a list of files in the current directory
- cd – Change directory
- quit – Close your ftp session
telnet command in Linuxtelnet command can be used to manage the compute remotely. It is less secure as compared to ssh command. Data is transferred in plain text.
ssh command in Linuxssh stands for Secure Shell Protocol. You can remotely login to computer and execute the commands using ssh command. Data is encrypted before transmission. Below command will show ssh version you are using.
$ ssh -V
route/arp command in Linuxroute command shows the kernel routing table. Here is the sample output.arp stands for address resolution protocol. arp command shows all ARP entries in the system.
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