Arrays in Bash

• Quotes from Bash Reference Manual: Arrays

  Any element of an array may be referenced using ${name[subscript]}. The braces
  are required to avoid conflicts with the shell's filename expansion operators.
  If the subscript is ‘@’ or ‘*’, the word expands to all members of the array
  name. These subscripts differ only when the word appears within double quotes.
  If the word is double-quoted, ${name[*]} expands to a single word with the
  value of each array member separated by the first character of the IFS
  variable, and ${name[@]} expands each element of name to a separate word. When
  there are no array members, ${name[@]} expands to nothing. If the double-quoted
  expansion occurs within a word, the expansion of the first parameter is joined
  with the beginning part of the original word, and the expansion of the last
  parameter is joined with the last part of the original word. This is analogous
  to the expansion of the special parameters ‘@’ and ‘*’.  ${#name[subscript]}
  expands to the length of ${name[subscript]}. If subscript is ‘@’ or ‘*’, the
  expansion is the number of elements in the array.  Referencing an array
  variable without a subscript is equivalent to referencing with a subscript of
  0.
  

• append

  a=(1 0 7 3)
  echo ${a[@]}
  #1 0 7 3
  b=(${a[@]} 8)
  echo ${b[@]}
  #1 0 7 3 8
  

• slice

  a=(1 0 7 3)
  echo ${a[0]}
  echo ${a[@]:1}  # from the 2nd till the end
  

• get a list of file names

  names=`ls ./`
  for name in $names; do echo $name; done
  

• convert string to array

  str='1 2 3 a b c'
  array=($str)
  

• or

  dd="random normal X1 link";
  for d in $dd; do
      echo $d;
  done;
  

• Join elements of an array

http://stackoverflow.com/questions/1527049/bash-join-elements-of-an-array

FOO=( a b c )
SAVE_IFS=$IFS
IFS=","
FOOJOIN="${FOO[*]}"
IFS=$SAVE_IFS
echo $FOOJOIN

#/!bin/bash
foo=('foo bar' 'foo baz' 'bar baz')
bar=$(printf ",%s" "${foo[@]}")
bar=${bar:1}
echo $bar

reference: The Ultimate Bash Array Tutorial with 15 Examples