Corrupting a string of random characters using bash

Question

I have a string which looks something like

/6435045045/hpdqbhflyuhv_EOlXG

I want to corrupt the string by changing a few characters. I did

$string | sed 's/E/A/g'

it worked fine but the string is dynamic and now the string is generated without an 'E' in it. Is it possible to corrupt the string by replacing first x characters with some random x characters using bash ??

score 2 · Accepted Answer · edited May 23 '17 at 12:28

2

> string="/6435045045/hpdqbhflyuhv_EOlXG"
> n=8
> m=`expr ${#string} - $n`
> string="`< /dev/urandom tr -dc A-Za-z0-9_ | head -c$n``echo $string | tail -c$m`"
> echo $string
oZeHdOD_45/hpdqbhflyuhv_EOlXG

edited May 23 '17 at 12:28

Community

1
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answered Aug 08 '13 at 17:27

andrew cooke

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score 0 · Answer 2 · answered Aug 08 '13 at 17:43

0

How rotten do you want to make the string?

tr 'A-Za-z' 'N-ZA-Mn-za-m' <<<$string

answered Aug 08 '13 at 17:43

David W.

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konsolebox · Answer 3 · 2013-08-08T18:15:19.717

This is one script in bash. It allows you to specify a character range and the number of times the contents of the string would be changed.

#!/bin/bash

# syntax: corrupt <string> <times> <character range in ascii codes>
#
function corrupt {
    local STRING=$1
    local STRING_LENGTH=${#1}

    local TIMES=$2

    local RANGE=("${@:3}")
    local RANGE_LENGTH="${#RANGE[@]}"

    local CHARS=()
    local C P I=0 IFS=''

    while read -rd $'\0' C; do
        CHARS[I++]=$C
    done < <(echo -ne "$(printf '\\x%x\\x00' "${RANGE[@]}")")

    for (( I = 0; I < TIMES; ++I )); do
        C=${CHARS[RANDOM % RANGE_LENGTH]}
        P=$(( RANDOM % STRING_LENGTH ))
        STRING="${STRING:0:P}${C}${STRING:P + 1}"
    done

    echo "$STRING"

    # Uncomment to save the value to variable __.
    # __=$STRING
}

corrupt "/6435045045/hpdqbhflyuhv_EOlXG" 10 {32..126}

Note: Increase the number (times) to a higher value to get more devastating results.

Corrupting a string of random characters using bash

3 Answers3