Convert command line arguments into an array in Bash

Question

How do I convert command-line arguments into a bash script array   I want to take this     something sh arg1 arg2 arg3   and convert it to   myArray   arg1 arg2 arg3     so that I can use myArray for further use in the script   This previous SO post comes close  but doesn t go into how to create an array  How do I parse command line arguments in Bash   I need to convert the arguments into a regular bash script array  I realize I could use other languages  Python  for instance  but need to do this in bash  I guess I m looking for an  append  function or something similar   UPDATE  I also wanted to ask how to check for zero arguments and assign a default array value  and thanks to the answer below  was able to get this working   if        -eq 0    then   myArray   defaultarg1 defaultarg2   else   myArray          fi

User · Answer

The importance of the double quotes is worth emphasizing. Suppose an argument contains whitespace.

Code:

#!/bin/bash
printf 'arguments:%s\n' "$@"
declare -a arrayGOOD=( "$@" )
declare -a arrayBAAD=(  $@  )

printf '\n%s:\n' arrayGOOD
declare -p arrayGOOD
arrayGOODlength=${#arrayGOOD[@]}
for (( i=1; i<${arrayGOODlength}+1; i++ ));
do
   echo "${arrayGOOD[$i-1]}"
done

printf '\n%s:\n' arrayBAAD
declare -p arrayBAAD
arrayBAADlength=${#arrayBAAD[@]}
for (( i=1; i<${arrayBAADlength}+1; i++ ));
do
   echo "${arrayBAAD[$i-1]}"
done

Output:

> ./bash-array-practice.sh 'The dog ate the "flea" -- and ' the mouse.
arguments:The dog ate the "flea" -- and 
arguments:the
arguments:mouse.

arrayGOOD:
declare -a arrayGOOD='([0]="The dog ate the \"flea\" -- and " [1]="the" [2]="mouse.")'
The dog ate the "flea" -- and 
the
mouse.

arrayBAAD:
declare -a arrayBAAD='([0]="The" [1]="dog" [2]="ate" [3]="the" [4]="\"flea\"" [5]="--" [6]="and" [7]="the" [8]="mouse.")'
The
dog
ate
the
"flea"
--
and
the
mouse.
>

User · Answer

Maybe this can help   myArray           also you can iterate over arguments by omitting  in    for arg  do    echo   arg  done   will be equivalent  for arg in    myArray       do    echo   arg  done

User · Answer

Side-by-side view of how the array and    are practically the same    Code      bin bash  echo  Dollar-1    1  echo  Dollar-2    2  echo  Dollar-3    3  echo  Dollar-AT      echo     myArray           echo  A Val 0    myArray 0    echo  A Val 1    myArray 1    echo  A Val 2    myArray 2    echo  A All Values    myArray        Input      bash-array-practice sh 1 2 3 4   Output   Dollar-1   1 Dollar-2   2 Dollar-3   3 Dollar-AT  1 2 3 4  A Val 0  1 A Val 1  2 A Val 2  3 A All Values  1 2 3 4

User · Answer

Easier Yet  you can operate directly on        Here is how to do pass a a list of args directly from the prompt    function echoarg   for stuff in        do echo  stuff   done            echoarg Hey Ho Lets Go     Hey     Ho     Lets     Go

User · Answer

Actually the list of parameters could be accessed with  1  2     etc  Which is exactly equivalent to      i    So  the list of parameters could be changed with set  and    i  is the correct way to access them      set -- aa bb cc dd 55 ff gg hh ii jjj kkk lll   for   i 0 i lt     i      do echo        i      i    done   12 1 aa 12 2 bb 12 3 cc 12 4 dd 12 5 55 12 6 ff 12 7 gg 12 8 hh 12 9 ii 12 10 jjj 12 11 kkk 12 12 lll   For your specific case  this could be used  without the need for arrays   to set the list of arguments when none was given   if        -eq 0    then     set -- defaultarg1 defaultarg2 fi   which translates to this even simpler expression              0     amp  amp  set -- defaultarg1 defaultarg2

User · Answer

Actually your command line arguments are practically like an array already  At least  you can treat the    variable much like an array  That said  you can convert it into an actual array like this   myArray            If you just want to type some arguments and feed them into the    value  use set     set -- apple banana  kiwi fruit    echo      3   echo      apple banana kiwi fruit   Understanding how to use the argument structure is particularly useful in POSIX sh  which has nothing else like an array

User · Answer

Here is another usage       bin bash array          arraylength    array     for    i 0  i lt   arraylength   i       do    echo    array  i    done

[arrays] Convert command line arguments into an array in Bash

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