Add a new element to an array without specifying the index in Bash

Question

Is there a way to do something like PHPs  array      foo   in bash vs doing   array 0   foo  array 1   bar

User · Answer

If your array is always sequential and starts at 0, then you can do this:

array[${#array[@]}]='foo'

# gets the length of the array
${#array_name[@]}

If you inadvertently use spaces between the equal sign:

array[${#array[@]}] = 'foo'

Then you will receive an error similar to:

array_name[3]: command not found

User · Answer

declare -a arr   arr   a     arr     arr       new     echo   arr     a new   arr     arr       newest     echo   arr     a new newest

User · Answer

As Dumb Guy points out  it s important to note whether the array starts at zero and is sequential  Since you can make assignments to and unset non-contiguous indices    array     is not always the next item at the end of the array     array  a b c d e f g h    array 42   i    unset array 2    unset array 3    declare -p array       dump the array so we can see what it contains declare -a array    0   a   1   b   4   e   5   f   6   g   7   h   42   i      echo    array     7   echo   array    array       h   Here s how to get the last index     end     array          put all the indices in an array   end   end     -1       get the last one   echo  end 42   That illustrates how to get the last element of an array  You ll often see this     echo   array    array     - 1   g   As you can see  because we re dealing with a sparse array  this isn t the last element  This works on both sparse and contiguous arrays  though     echo   array     -1  i

User · Answer

With an indexed array  you can to something like this   declare -a a    a    foo   bar

User · Answer

Yes there is   ARRAY    ARRAY    foo   ARRAY    bar     Bash Reference Manual      In the context where an assignment statement is assigning a value to a shell variable or array index  see Arrays   the          operator can be used to append to or add to the variable s previous value

[bash] Add a new element to an array without specifying the index in Bash

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