Introduction to Bash

[alienfader]

Hello all,
I currently having issues with the first task of Introduction to Bash Scripting on the HTB Academy platform.
Here is the code in question:

#!/bin/bash
# Count number of characters in a variable:
#     echo $variable | wc -c

# Variable to encode
var="nef892na9s1p9asn2aJs71nIsm"

for counter in {1..40}
do
        var=$(echo $var | base64)
done

The question is " Create an “If-Else” condition in the “For”-Loop of the “Exercise Script” that prints you the number of characters of the 35th generated value of the variable “var”. Submit the number as the answer."

I tried many different approaches but keep getting the wrong answers. Can someone nudge me on the right direction?
Here is my code:

 #!/bin/bash

# Variable to encode
var="nef892na9s1p9asn2aJs71nIsm"

for counter in {1..40}
do
    var=$(echo -n $var | base64 -w 0)

    if [ $counter -eq 35 ]; then
        num_chars=${#var}
        echo "Number of characters in the 35th encoded value: $num_chars"
    fi

done

Thanks in Advance.

[marek33366]

[alienfader]

Thank you for your reply.
That code did not work right away(Illegal number: {1…40}) but I found a workaround.

var="nef892na9s1p9asn2aJs71nIsm"

for ((counter=1; counter<=40; counter++))
do
  var=$(echo $var | base64)
  if [ $counter -eq 35 ]
  then
    echo "The number of characters of the 35th generated value of the variable var is: $(echo $var | wc -c)"
  fi
done

I sincerely appreciate the help @marek33366
Cheers

[marek33366]

no problem good job for your debug

[emdeh]

I thought I would add a bit more context to this for any future readers, as I was a bit confused about how this worked, to begin with.

Here is a solution with some explanatory comments.

#!/bin/bash
# Count number of characters in a variable:
#     echo $variable | wc -c

# Variable to encode
var="nef892na9s1p9asn2aJs71nIsm"

for counter in {1..40}  # The `for` loop iterates 40 times.
do
	var=$(echo $var | base64)  # `var` piped into the `base64` command & the output reassigned to `var`.
    	if [[ $counter -eq 35 ]] # Conditional if statement checks if the iteration number (counter) is 35.
    	then
    		echo $(echo $var | wc -c)
# This part sends the content of var to wc -c, which counts the number of characters.
#  $(...) is a command substitution. The shell first executes the command inside the parentheses and then replaces $(...) with the output of that command.
# echo $(...) then outputs the result of the command substitution.
    	fi
done

[john_smith1]

Your script looks almost correct. However, the issue might be with the encoding part. When you encode the variable using base64, it adds a newline character by default. To avoid this, you can use the -n option with the echo command to suppress the trailing newline. Here’s the corrected version of your code:

#!/bin/bash

# Variable to encode
var="nef892na9s1p9asn2aJs71nIsm"

for counter in {1..40}
do
    var=$(echo -n $var | base64)

    if [ $counter -eq 35 ]; then
        num_chars=${#var}
        echo "Number of characters in the 35th encoded value: $num_chars"
    fi

done

By adding the -n option to the echo command, you ensure that the encoded value doesn’t contain any extra characters, which might affect the character count. This should help you get the correct answer for the task. #steelflanges