Gen random char then sed replacements

Shell Programming and Scripting
1

Hey guys,

I need to first generate some random characters, which I am already doing perfectly as follows:

randomize=`cat /dev/urandom | tr -dc "a-z0-9" | fold -w 6 | head -n 1`

This is where I am stuck...I need to sed replace some static values with those random characters, but I need each replacement to have *different* random characters...for example:

sed -i 's/blah/blah?$randomize/g' /home/test.html

^ Above does not work ... but it would replace all occurrences of "blah" with blah?au2bu and blah?d2g3h and blah?3juh4 ... I don't want them to all be blah?au2bu

Thanks for the help!

2

If you aren't dead set on using sed, you could try something like this:

#!/usr/bin/env ksh

awk  -v pattern="${1:-boo}" '
    function gen(       j, i, c )       # gen random replacement words
    {
        ridx = 0;
        for( i = 0; i < 500; i++ )
        {
            for( j = 0; j < word_len; j++ )
                rword = rword substr( soup, ((int(rand( ) *1000)) % length( soup )) + 1, 1 );
        }
    }
    BEGIN {
        soup = "abcdefghijklmnopqrstuvwxyz01234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ";   # xlation
        word_len = 5;       # random word size
        gen();
     }

    {
        while( sub( pattern, "<goop>" rword[ridx++], $0 ) );    # assume <goop> is not in any input data nor the pattern
            if( ridx >= 500 )
                gen();
        gsub( "<goop>", pattern "?" );
        print;
    }
' "$@"

Reads from standard input or filename(s) supplied on the command line, writes to stdout. The word size can be changed.

Test input:

Now is the time to test
Forever is the time to try the programme
now the final sentance is here the end.

Test output with the command test.ksh the <data

Now is the?LC00s time to test
Forever is the?ON2nl time to try the?5berE programme
now the?jn1BE final sentance is here the?cJod1 end.
3

Hi Agama,

Thank you for that, but it seems a bit complicated...

This is working atm...

# Random character generator
randomizer()
{
randomize=`cat /dev/urandom | tr -dc "a-z0-9" | fold -w 6 | head -n 1`
result=$randomize
}

randomizer
echo $result

randomizer
echo $result

But I have to keep calling randomizer in order to make it get a fresh result and also when I call sed with $result, it makes all replacements the same rather than unique $result

4

Yes, you'll have to 'get a bit more complicated' if you want each replacement to be different.

5

Thanks Agama!