hey guys welcome to the next blog on shell scripting tutorial for beginners in this blog we will see how we can use arrays in shell scripting now bash suppose simple one-dimensional arrays and to declare arrays you just need to use the name of the array so whatever name you want to give to your array variable just give it for example you want to have operated system array variables so I will just write OS is equal to this is the name of the array o X right and then you just use this parent ever and in the single quotes you just add the element to the array so for example I will just add Ubuntu here and then separate it by a space no comma you just need to add things a second the elements for example windows and so on so third for example we will add Kali Linux or Kali right and just save it and to print this array you just need to use echo and I think in the first few blogs we have read how we can print array but we will repeat this thing so just use dollar symbol and then in the curly bracket name of the array or a name is OS and then in the square bracket use the special character at the rate which is going to print the elements of the array so let's run the script and let's see what happens so you can see it prints the elements of the array right now in order to print any specific element you just need to use echo and once again dollar symbol curly brackets name of the array and
the square bracket the index of the element which you want to print so for example I want to print Windows which is the first element and how it's the first element or for the first index the element or index of the array starts from the 0th position so this is the index 0 this is the index 1 and this is at the index 2 right so index 1 is assigned to the windows element right so let's run the script once again and let's see what happens so it prints windows if you right here 0th index it's going to print ubuntu right and let's go ahead and i'm going to show you how you can print the indexes or indices of the array so you just need to use once again the dollar symbol and the curly bracket and the name of the array and once again in the square bracket use the add the rate but this time here you just need to use not symbol this exclamation mark okay and let's see what happens when we run the script and you can see it trains the indexes of the array or indices of the array right so we have 3 element which starts from 0 1 2 so it prints 0 1 2 ok now for example you want to print the length of the array what we will do we will just write echo and once again echo and then the dollar symbol once again and then the square bracket name of the array and in the square bracket you just need to write at the rate special character and in front of the array variable name you just need to add this hash symbol okay and this means you want to print the length of the array okay so let's run the script and let's see what happens so you can see the array length in our case is 3 because it contains 3 elements right now how we can add elements to the array so to add elements you just need to write the name of the array and then whatever index at whatever index you want to add an element you just need to write the index of that element so for example I want to add at the index 3 some other OS name so for example I want to write Mac here okay so this will be added to the third index of this array now let's see what happens when we run the script you can see here this fourth element is added to an array at the index three right so in this way you can add the element now if you want to update this so for example I right here at the 0th index then this Mac will be assigned at the 0th index which is going to replace this ubuntu by Mac right so let's run the script and you can see now it has at the 0th index Mac then Windows then Kali okay so if you want to update it you just need to write the index of the element which you want to replace the new element with and then you just assign the element value okay now we will see how we are going to remove how can we remove element from an array so to remove an element from an array what we will do we will use the keyword unset so just write unset and then the name of the array so money array name is where and then whatever index of the element you want to remove so for example I want to remove the index at which Kali Linux is let me just edit this index also so Mac is at the third index right and Kali is at the second index so 0 1 2 ok so I am going to remove the callee from my array right so just write the index value of the element which you want to remove and then once again run the script and you can see now we have open to Windows and Mac and no Colleen right now you may ask why it's printing like this because we already have removed the element at index two right so it's like that that in bash you can add element at any index so it can be for example at fixed index and nothing is going to happen it's going to print the elements of the array in the sequence of the index right so if it it's at the fixed index it will be sorted in the ascending order so 0 1 and then if it it it is at the 6th position or index and it's going to just print the value at the fixed index and now this position will be ignored so this means that some members of the array can be left uninitialized and gaps in the arrays are okay now bash permits arrays operation on variables also even if the variables are not explicitly declared as an arrays so let's take an example so I have a variable name called string for example and I assign any value to it so let's say this random string right now when I I will just take this echo come on here and then I will just print the string right string array and let's see what happens so let me clear the terminal and let's run the script once again and you can see here it prints the you know array or string value as it is right so you can see string is printed right so taking this string as an array so you can use this kind of notation also but let's print for example the 0th index of the array so once again I'm going to just write 0 here instead of at the rate I will just write 0 and then once again run the script and it prints the same string value right let me just print the index 1 value and here the magic happens you can see at index 1 there is nothing so why this is happening because you are going to treat any variable as an array the array element value at 0 10 Dex whatever the value of the variable it's assigned at the 0th index right so you can treat any variable as an array but the value of this array will be assigned to the 0th index okay so at the first index there is nothing because the whole value is assigned to the 0th index and this we can prove by printing the length of the array also so let's print the length of this string array and let's see what happens so you can see the length of the string array is only 1 which is this one ok so this is how you can use arrays in bash scripting I hope you've enjoyed this BLOG 😊
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