Arrays in unix shell

Question

How do I create an array in unix shell scripting

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An array can be loaded in twoways   set -A TEST ARRAY alpha beta gamma   or  X 0   Initialize counter to zero    -- Load the array with the strings alpha  beta  and gamma  for ELEMENT in alpha gamma beta do     TEST ARRAY  X   ELEMENT       X   X   1   done   Also  I think below information may help      The shell supports one-dimensional arrays  The maximum number of array   elements is 1 024  When an array is defined  it is automatically   dimensioned to 1 024 elements  A one-dimensional array contains a   sequence of array elements  which are like the boxcars connected   together on a train track    In case you want to access the array   echo   MY ARRAY 2    Show the third array element  gamma    echo   MY ARRAY      Show all array elements -   alpha beta gamma   echo   MY ARRAY      Show all array elements  -  alpha beta gamma   echo    MY ARRAY       Show the total number of array elements -   3   echo    MY ARRAY       Show the total number of array elements -   3  echo   MY ARRAY    Show array element 0  the first element  -  alpha

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There are multiple ways to create an array in shell   ARR 0   ABC  ARR 1   BCD  echo   ARR         ARR     prints all elements in the array   Second way is   ARR   A   B   C   D  5 7  J   echo    ARR     echo   ARR 0        ARR     is used to count length of the array

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The following code creates and prints an array of strings in shell      bin bash array   A   B   ElementC   ElementE   for element in    array      do     echo   element  done  echo echo  Number of elements     array      echo echo    array        Result   A B ElementC ElementE  Number of elements  4  A B ElementC ElementE

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In ksh you do it   set -A array element1 element2 elementn    view the first element echo   array 0      Amount elements  You have to substitute 1  echo    array        show last element echo   array         array     - 1

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You can try of the following type       bin bash  declare -a arr   i 0  j 0    for dir in   find  home rmajeti programs -type d     do         arr i   dir         i    i 1      done     while    j -lt  i     do         echo   arr  j           j    j 1     done

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bin bash    define a array  space to separate every item foo  foo1 foo2     access echo    foo 1       add or changes foo 0  bar foo 2  cat foo 1000  also OK   You can read the ABS  Advanced Bash-Scripting Guide

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The Bourne shell and C shell don t have arrays  IIRC   In addition to what others have said  in Bash you can get the number of elements in an array as follows   elements    arrayname       and do slice-style operations       arrayname  apple banana cherry  echo   arrayname    1                      yields  banana cherry  echo   arrayname     -1                    yields  cherry  echo   arrayname    arrayname    -1        yields  cherry  echo   arrayname    0 2                    yields  apple banana  echo   arrayname    1 1                    yields  banana

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Bourne shell doesn t support arrays  However  there are two ways to handle the issue   Use positional shell parameters  1   2  etc      set one two three   echo    one two three   echo    3   echo  2 two   Use variable evaluations     n 1   eval a n  one     n 2   eval a n  two     n 3   eval a n  three    n 2   eval echo   a n two

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To read the values from keybord and insert element into array    enter 0 when exit the insert element echo  Enter the numbers  read n while    n -ne 0   do     x  i   expr  n      read n     let i   done   display the all array elements echo  Array values   x      echo  Array values   x         To find the array length length    x     echo  length

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If you want a key value store with support for spaces use the -A parameter   declare -A programCollection programCollection  xwininfo    to aquire information about the target window    for program in    programCollection     do     echo  The program   program  is used   programCollection   program     done   http   linux die net man 1 bash  Associative arrays are created using declare -A name

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Your question asks about  unix shell scripting   but is tagged bash  Those are two different answers   The POSIX specification for shells does not have anything to say about arrays  as the original Bourne shell did not support them  Even today  on FreeBSD  Ubuntu Linux  and many other systems   bin sh does not have array support  So if you want your script to work in different Bourne-compatible shells  you shouldn t use them  Alternatively  if you are assuming a specific shell  then be sure to put its full name in the shebang line  e g     usr bin env bash   If you are using bash or zsh  or a modern version of ksh  you can create an array like this   myArray  first  second element  3rd    and access elements like this    echo    myArray 1    second element   You can get all the elements via    myArray       You can use the slice notation   array    start length  to restrict the portion of the array referenced  e g     myArray    1   to leave off the first element   The length of the array is    myArray      You can get a new array containing all the indexes from an existing array with     myArray          Older versions of ksh before ksh93 also had arrays  but not the parenthesis-based notation  nor did they support slicing   You could create an array like this  though   set -A myArray -- first  second element  3rd

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in bash  you create array like this  arr  one two three    to call the elements    echo    arr 0    one   echo    arr 2    three   to ask for user input  you can use read  read -p  Enter your choice    choice

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A Simple way    arr   sharlock    bomkesh    feluda       declare array  len    arr       determine length of array    iterate with for loop for    i 0  i lt len  i      do     echo   arr  i   done

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Try this     echo  Find the Largest Number and Smallest Number of a given number  echo  ---------------------------------------------------------------------------------  echo  Enter the number  read n i 0  while    n -gt 0    For Seperating digits and Stored into array  x  do         x  i   expr  n   10          n  expr  n   10          i  expr  i   1  done  echo  Array values   x         For displaying array elements   len    x        it returns the array length   for    i 0  i lt len  i           For Sorting array elements using Bubble sort do     for    j i 1  j lt len   j          do         if    echo    x  i    gt    x  j    bc            then                 t   x  i                   t   x  i                   x  i    x  j                   x  j   t         fi         done done   echo  Array values   x         Displaying of Sorted Array   for    i len-1  i gt  0  i--       Form largest number do    a  echo  a    10     x  i   bc  done  echo  Largest Number is    a   l  a   Largest number  s 0 while    a -gt 0      Reversing of number  We get Smallest number do         r  expr  a   10          s  echo   s   10    r  bc          a  expr  a   10  done echo  Smallest Number is    s   Smallest Number  echo  Difference between Largest number and Smallest number  echo                                              Diff  expr  l -  s  echo  Result is    Diff    echo  If you try it  We can get it

[arrays] Arrays in unix shell?

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