Shell – Set variable to random item in array

you should handle that stuff in the index evals. and you can indirect through your indirection variable's indices if you make it an array.

a=(abc1 def2 ghi3 jkl4 mno5)
r=('a[c=${#a[@]}]' a\[i] a\[@])
for   i in   0 1 2 3 4 5
do    c=
      printf "<%s>\n" "${!r-${!r[i<c?1:2]}}"
      printf "\n\tindex is $i and count is $c\n\n"
done

<abc1>

    index is 0 and count is 5

<def2>

    index is 1 and count is 5

<ghi3>

    index is 2 and count is 5

<jkl4>

    index is 3 and count is 5

<mno5>

    index is 4 and count is 5

<abc1>
<def2>
<ghi3>
<jkl4>
<mno5>

    index is 5 and count is 5

Because bash's indices are 0-based, the total count of array objects will always work out to one more than than the highest set index, and so:

c=
echo "${a[c=${#a[@]}]-this index is unset}" "$c"

this index is unset 5

...the parameter expands out to the default word if any is provided.

If one is not provided:

c=
${!r}
echo "$c"

5

...there's no harm done.

In the loop I track an $index variable and check if it is at least as large as $count. When it is lesser I expand the $reference var to a[i] because it is a valid index, but when it is equal or greater I expand the $ref to the entire $array.

Here it is in a function:

ref_arr(){
    local    index=-1 count=
    local    ref=(   "$1[ count= \${#$1[@]}  ]"
                     "$1[ index ]"    "$1[ @ ]"
    )  &&    printf  "input array '%s' has '%d' members.\n" \
                     "$1"  "${!ref-${count:?invalid array name: "'$1'"}}"
    while    [ "$((index+=1))" -lt "$count"  ]
    do       printf  "$1[$index]  ==  '%s'\n"  "${!ref[1]}"
    done
}
some_array=(some "dumb
            stuff" 12345\'67890 "" \
          '$(kill my computer)')
ref_arr some_array
ref_arr '$(echo won'\''t work)'

input array 'some_array' has '5' members.
some_array[0]  ==  'some'
some_array[1]  ==  'dumb
                stuff'
some_array[2]  ==  '12345'67890'
some_array[3]  ==  ''
some_array[4]  ==  '$(kill my computer)'
bash: count: invalid array name: '$(echo won't work)'

Here is a sample script which you can use to implement this:

#!/bin/bash

shopt -s extglob
readonly URL="https://google.com"
links=($(grep -o -P '(?<=href=").*(?=")' source.html)) # read into array

for ((i=0; i<${#links[@]}; i++))
do
  case ${links[$i]} in
    http*)
      : # do nothing
      ;;
    /*)  
      links[$i]="$URL"${links[$i]}; # update array
      ;; 
    *)
      links[$i]="$URL/"${links[$i]}; # update array
      ;;
  esac
done

It assumes source.html is the downloaded source of the web page in the current directory.