blog | We Can Code

Learn to write your first shell script

by WeCanCode-Author | Dec 27, 2020 | 3 Minutes : Tutorials, How-To

Learn to write your first shell script to print “Helloworld”?

Come lets Learn to write your first shell script will be the baby step for learning shell programming.

Any programming language or script it be, start it with “Hello world”.

Why start with Hello world?

Writing your first program to print “Hello world”, will allow you to learn the basic setup of the environment, configurations, and more.

https://youtu.be/yxmI8pS2wN0

hello_world.sh

#!/bin/bash
echo "Hello world"

Save the file, then to run open the terminal, and type ./hello_world.sh

PS: You might get permission denied error, due to hello_world.sh file not having execute permission for any users.

Use “chmod +x hello_world.sh” to provide execute permission.

This first line (#!/bin/bash or #!/bin/sh) has a name. It is known as ‘she-bang‘ (shabang). This derives from the concatenation of the tokens sharp (#) and bang (!).
It is also called as sh-bang, hash-bang, pound-bang or hash-pling. In computing, a she-bang is the character sequence consisting of the characters number sign and exclamation mark (#!) at the beginning of a script.

More 3 Minutes: Tutorials here

Check disk usage in unix terminal?

by WeCanCode-Author | Dec 27, 2020 | 3 Minutes : Tutorials, How-To

How to check disk usage in unix terminal?

Here is how you can check disk usage in unix terminal.

Disk usage is a critical thing in servers, Certain times the web service or server acts weird and it could be disk space being full.

In order to check the disk space we can use “df” command in unix. which will show us the disk/file system, used and available disk quantity. also the mount location of the disk.

We have discussed below listed commands

df – disk usage checking
man – man is nothing but manual, by passing the command as parameter to this command will open the manual for the command in parameter.

https://youtu.be/kqVzUOZMSY0

df command

aryanz_co_in@pop-os:~$ df -h
df: /run/user/1001/doc: Operation not permitted
Filesystem      Size  Used Avail Use% Mounted on
tmpfs           1.6G  2.1M  1.6G   1% /run
/dev/sda2       723G  111G  575G  17% /
tmpfs           7.8G   87M  7.7G   2% /dev/shm
tmpfs           5.0M     0  5.0M   0% /run/lock
tmpfs           4.0M     0  4.0M   0% /sys/fs/cgroup
/dev/sda1       1.5G  199M  1.3G  14% /boot/efi

More 3 Minutes: Tutorials here

Check disk usage in unix? — ~3Minutes: Tutorial

Check the port used by any process in unix?

by WeCanCode-Author | Dec 25, 2020 | 3 Minutes : Tutorials, How-To

Here we are going to see how to Check the port used by any process in unix?

Check the port used by any process in unix?

Here is how you can check port used by any process in unix terminal.

While developing any webservice or web server you might end up using existing port number and will face issue while starting the server

Before such thing happens, better to check the port is being used by any process already to avoid such conflicts. Its saves us more time.

We have discussed below listed commands

netstat – network utility used for checking the connection of TCP/UDP
ss – Socket statistics, similar to netstat but faster.
sudo – Run any command with root or super user level/mode.

https://youtu.be/kqVzUOZMSY0

netstat command

aryanz_co_in@pop-os:~/dev/folder1$ sudo netstat -tulpn
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name    
tcp        0      0 127.0.0.1:33060         0.0.0.0:*               LISTEN      5314/mysqld         
tcp        0      0 127.0.0.1:3306          0.0.0.0:*               LISTEN      5314/mysqld         
udp        0      0 127.0.0.53:53           0.0.0.0:*                           4434/systemd-resolv

ss command

aryanz_co_in@pop-os:~/dev/folder1$ sudo ss -tulpn
Netid           State            Recv-Q           Send-Q                     Local Address:Port                       Peer Address:Port           Process                                                                                                                                           
udp             UNCONN           0                0                          127.0.0.53%lo:53                              0.0.0.0:*               users:(("systemd-resolve",pid=4434,fd=12))                                                                                                                                                                                                           
tcp             LISTEN           0                70                             127.0.0.1:33060                           0.0.0.0:*               users:(("mysqld",pid=5314,fd=32))                                                                                                                
tcp             LISTEN           0                151                            127.0.0.1:3306                            0.0.0.0:*               users:(("mysqld",pid=5314,fd=34))

More 3 Minutes: Tutorials here