\n
Here, the expression ${shoes[-1]}<\/code> accesses the last element nike <\/strong>of the array shoes <\/strong>using the negative index \u2018-1\u2019<\/strong> and the echo "last item:${shoes[-1]}"<\/code> command prints the value nike<\/strong> on the screen.<\/p>\n<\/div><\/div>![\"access](\"https:\/\/linuxsimply.com\/wp-content\/uploads\/2023\/11\/3-last-item.png\")
<\/p>\n<\/span>Loop Through the Elements of Array in Bash<\/span><\/h2>\nUsing Bash loop-based methods are general approach to iterate over an array. To loop through the Bash array elements using for<\/strong> loop with the syntax for elem in ${array[@]}<\/strong>, see the example below:<\/p>\n#!\/bin\/bash\n\n#Declaring an indexed array and assigning it with values \nfruit=(lichie pine orange)\n\n#looping through the elements to print \nfor item in ${fruit[@]}\n do\n echo $item\ndone \n<\/code><\/pre>\n EXPLANATION<\/div>
\n
First, the complete looping expression for elements in ${fruit[@]}<\/code> iterates through the fruit<\/strong> array until it covers the entire array length (which is 3)<\/strong> and prints the items into the terminal iteratively on new lines using echo $item<\/code>.<\/p>\n<\/div><\/div>![\"loop](\"https:\/\/linuxsimply.com\/wp-content\/uploads\/2023\/11\/4-loopelems.png\")
<\/p>\n<\/span>Add Array Elements<\/span><\/h2>\nAdding a new element in an array is very simple in Bash. Use the =+<\/strong> operator with the syntax array_name+=(element to add)<\/strong>. By default, it adds an element to the end of the specified array.<\/p>\nHere\u2019s an example to add an array element CSE<\/strong> in an indexed array named dept<\/strong> using syntax dept+=(CSE)<\/code>:<\/p>\n#!\/bin\/bash\n\n#array declaration with elements \ndept=(EEE CE)\n\n#print array before append\necho "before: ${dept[@]}"\n\n#append element\ndept+=(CSE)\n\n#print array after append\necho "after adding new element: ${dept[@]}"\n<\/code><\/pre>\n EXPLANATION<\/div>
This script uses the syntax\u00a0
dept+=(CSE)<\/strong> to add a new element CSE<\/strong> to the end of the dept<\/strong> array with 2 elements. The final echo<\/strong> command prints the array with 3 elements (EEE CE CSE)<\/strong>.<\/p>\n<\/div><\/div>![\"adding](\"https:\/\/linuxsimply.com\/wp-content\/uploads\/2023\/11\/5-addelem1.png\")
The snap above shows that the dept+=(CSE)<\/strong> expression adds a new element to the array dept which is evident after printing the array in the last line.<\/p>\n\n
NOTE<\/strong>: To add multiple elements to an array, use array+=(item1 item2 ..ItemN)<\/strong>. For instance, to add MME<\/strong> and ECE<\/strong> to the above array, the syntax is: dept+=(MME ECE)<\/code><\/div><\/div>\n<\/span>Add Array Elements Using Index Assignment<\/span><\/h3>\nThe index assignment syntax array_name[index]=element<\/strong> adds a new element to an existing Bash array in any specified index.<\/p>\nI\u2019ll use the same dept array to add 2 new elements Arch<\/strong> and CEE<\/strong> at index 2 and index 10 using the index assignment syntaxes dept[2]=Arch<\/code> and dept[10]=CEE<\/code>. Here\u2019s how:<\/p>\n#!\/bin\/bash\n\n#array declaration with elements \ndept=(EEE CE)\n\n#print array before append\necho "before: ${dept[@]}"\n\n#append element\ndept[2]=Arch\ndept[10]=CEE\n\n#print array after append\necho "after adding new elements: ${dept[@]}"\n\n#print index\necho "the indices are: ${!dept[@]}"\n<\/code><\/pre>\n EXPLANATION<\/div>
In this script, the
dept[2]=Arch<\/strong> add a new element Arch<\/strong> to the dept<\/strong> array at the 3rd position. The dept[10]=CEE <\/strong>expression adds CEE<\/strong> to the array in the 4th position but with index number 10. The echo<\/strong> command prints the array and all the indices to verify the successful running of operations using echo "after adding new elements: ${dept[@]}"<\/code> and echo "the indices are ${!dept[@]}"<\/code><\/p>\n<\/div><\/div>![\"adding](\"https:\/\/linuxsimply.com\/wp-content\/uploads\/2023\/11\/6-addelem2.png\")
Here, you can see that the assignment expression above adds 2 new elements (Arch CEE)<\/strong> to the dept <\/strong>array both in a contiguous manner (index 2)<\/strong> and in a random manner (index 10)<\/strong>.<\/p>\n<\/span>Modify Array Elements in Bash<\/span><\/h2>\nTo modify an array element is to replace the extant value with a new value in the same position. The syntax\u00a0array[index]= new_value<\/strong>modifies the array element by updating with the new_value<\/strong> at the specified index<\/strong>. Here\u2019s an example:<\/p>\n#!\/bin\/bash \n#Declaring the array \nhello=("i" "am" "kohli") \n\n#Printing all the elements of the Array \necho "before:${hello[@]}"\n\n#Updating the Array Element \nhello[2]=williamson \n \n#Printing all the elements of the Array \necho "after modification:${hello[@]}"\n<\/code><\/pre>\n EXPLANATION<\/div>
\n
Here, the hello[2]=williamson<\/code> expression updates the content of index 2 (3rd position) from kohli to williamson. The echo "after modification:${hello[@]}"<\/code> command prints the array with the updated contents.<\/p>\n<\/div><\/div>![\"modify](\"https:\/\/linuxsimply.com\/wp-content\/uploads\/2023\/11\/7-modify-elem.png\")
Terminal output to modify the array element from kohli to williamson<\/strong>.<\/p>\n<\/span>Remove Array Elements<\/span><\/h2>\nTo delete an array element, use the unset command followed by the index value like the format: unset array_name[index]<\/code><\/p>\nHere\u2019s an example to show how to remove an element from an indexed array:<\/p>\n
#!\/bin\/bash\n\n#create an indexed array\njuice=("apple" "banana" "cherry" "date" "kiwi")\n\n#print the entire array\necho ${juice[@]}\n\necho\n\n#remove the element banana\nunset juice[1]\n\n#print array again\necho ${juice[@]}\n<\/code><\/pre>\n EXPLANATION<\/div>
\n
In the script, the unset juice[1]<\/code> command removes the 2nd element banana<\/strong>. After that, the echo<\/strong> command prints the array twice to show that the unset command has removed the array element.<\/p>\n<\/div><\/div>![\"removing](\"https:\/\/linuxsimply.com\/wp-content\/uploads\/2023\/11\/8-remove-Elem.png\")
In the above, the unset<\/strong> command removes the element banana from the array juice.<\/p>\n