Shell Programming and Scripting

Hi there im totally new to shell scripting and i find it very interesting. I come from java programming background.

Basically what i need is to loop a string of say all possible permutations of 20 displayable characters and md5 hash the string till it produces a 128 bit hash value with say 4 leading hex zeros. (meaning the first 4 characters of the hash value) Is this possible in shell scripting? (bash)

Thanks for the help!!!

My overly simplistic answer would be: yes, anything's possible in shell scripting...

Not to be a wise-guy, but loops are loops...and most languages are simply restacks of others based on the priorities, preferences and motivations of their developers. How would you have done it in your Java background? Start there and we can help you restage it in your new syntax...

After reading some tutorials on shell scripting I got a rough idea...

What I am trying to do is to do a loop on concatStr such that it goes from 0000 to 0001 and 0002 and so forth, each time running thru the md5sum function.

Can anyone help me with the loop syntax?

Code:

concatStr="0000"

echo $concatStr | md5sum

Moderator's Comments:

How to use code tags

Code:

for val in $( seq -w 0 9999 )
do
  echo $val | md5sum
done

--ahamed

Thanks for the reply bro,

i did try that... but its not what im looking for. using that, the values are from 0, 1, 2, 3 to 9999 what i need is 0000, 0001, 0002, 0003, to 9999... prefix 0 must be in front in short...

-w in seq serves the purpose of equal width.

Code:

root@bt > for val in $( seq -w 0 9999 ); do echo $val ; done | more
0000
0001
0002
0003
0004
0005
0006

--ahamed

Thanks it worked!!! awesome!!!

Code:

for i in $( seq -w 0000 9999)
do
  echo $i | md5sum >> /home/ubuntu/Documents/log
done

I got one problem though, when the echo logs into the log file, is there any way to make it stop when one of the md5sum starts with 000000?

example hash value: 000000d414474e4033ac29ccb8653d9b

Moderator's Comments:

How to use code tags when posting data and code samples.