“[0: command not found” in Bash [duplicate]

Answer 1

Need a space after [ and no space before or after = in the assignment. $(($i+1))) would try to execute the output of the ((...)) expression and I am sure that's not what you want. Also, you are missing a $ before the array name.

With these things corrected, your while loop would be:

#!/bin/bash
i=0
while [ "$i" -le "${#myarray[@]}" ]
do 
  echo "Welcome $i times"
  i=$((i + 1))
done

• i=$((i + 1)) can also be written as ((i++))
• it is always better to enclose variables in double quotes inside [ ... ]
• check your script through shellcheck - you can catch most basic issues there

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See also:

• Why should there be a space after '[' and before ']' in Bash?
• How to use double or single brackets, parentheses, curly braces
• Command not found error in Bash variable assignment
• Using [ ] vs [[ ]] in a Bash if statement