[SOLVED] uuencode

taylorkh · 03-30-2021, 08:07 AM

Many years ago I took an image file, ran it through uuencode (on a Windoze machine), cut 10 columns from the resulting file and have used that data for years as a source of random passwords. Recently I observed that ALL of my passwords start with "M". I obviously changed the first character to M for some reason but I have no idea why. I decided to generate some new passwords.

I installed sharutils on my CentSOS 7 machine. Based on the man page

Code:

SYNOPSIS
       uuencode [-flag [value]]... [--opt-name[[=| ]value]]... [ in-file ] output-name

I should be able to execute

Code:

uuencode Greta\ Granstedt.jpg Greta.uu

However, no output file is created. The uuencoded data is displayed in the terminal. If I try redirecting

Quote:

uuencode Greta\ Granstedt.jpg > Greta.uu

control does not return to the terminal until I press Ctrl-D. The resulting file contains

Code:

begin 664 Greta Granstedt.jpg
`
end

I have searched and read at least a half dozen tutorials/examples which seem to confirm this syntax. I tried the same operation on Linux Mint 20. Same thing. It can't be this hard

What am I doing wrong?

TIA,

Ken

p.s. See Greta Grandstedt in "Street Scene" on IMDB. You can probably guess which picture I have chosen

jpollard · 03-30-2021, 08:21 AM

Not a fix, as what you got is rather odd...

You might try using the "-m" option and see if it does something a bit different.

In the original version of uuencode/uudecode they were expecting their input to be from STDIN and would merge the output into a mail message or decode the mail message and create the output file.

In your case, (due to the command not terminating until ^D was entered), try:

uuencode <Greta\ Granstedt.jpg > Greta.uu

shruggy · 03-30-2021, 08:22 AM

From its man page:

Quote:

Note: uuencode uses buffered input and assumes that it is not hand typed from a tty. The consequence is that at a tty, you may need to hit Ctl-D several times to terminate input.

But why use uuencode at all?

Code:

base64 -w10 /dev/urandom|head

jpollard · 03-30-2021, 08:51 AM

Quote:

Originally Posted by shruggy

From its man page:

But why use uuencode at all?

Code:

base64 -w10 /dev/urandom|head

I thought it was partially due to historical operation and might be needed for decoding elsewhere.

But yes, using base64 would likely provide the equivalent activity.

taylorkh · 03-30-2021, 08:53 AM

Thanks jpollard,

I had tried -m. Same issue. The uuencode output looks different of course and is what I would use as a password source (no _ characters.) I tried your suggestion but it failed with a status code of 1 (The operation failed or the command syntax was not valid.)

Code:

uuencode -m <Greta_Granstedt.jpg > Greta.uu
uuencode (GNU sharutils) - encode a file into email friendly text - Ver. 4.13.3
USAGE:  uuencode [ -<flag> | --<name> ]... [ in-file ] output-name

Notice that I also removed the space from the input file name. No improvement.

Thanks shruggy,

I read that note and have used Ctrl-D when necessary. Why uuencode? Why not? I thought it was a rather creative process back when I first did it. It SHOULD still work and I would like to get a handle on it. Who knows, I might want to post something to Usenet

Ken

shruggy · 03-30-2021, 08:58 AM

Quote:

Originally Posted by taylorkh

The operation failed or the command syntax was not valid.

Because it is invalid. uuencode requires a file name to be specified on the command line. The output goes to stdout nevertheless. The file name is only needed in order to be recorded in the first line of the uuencoded file, so that uudecode could restore it when reading from stdin.

jpollard · 03-30-2021, 09:09 AM

Quote:

Originally Posted by shruggy

Because it is invalid. uuencode requires a file name to be specified on the command line. The output goes to stdout nevertheless. The file name is only needed in order to be recorded in the first line of the uuencoded file, so that uudecode could restore it when reading from stdin.

THAT is what I forgot. The name is for the output not the input data.

taylorkh · 03-30-2021, 09:15 AM

Thanks again shruggy,

I see the original file name in the "output" file when I try to redirect the output

Quote:

uuencode -m Greta_Granstedt.jpg > Greta.uu

produces

Code:

begin-base64 664 Greta_Granstedt.jpg
====

Something strange is going on.

Ken

taylorkh · 03-30-2021, 09:20 AM

Thanks once more jpollard,

There must be a way to dump the results of uuencode to a FILE. Otherwise people could not have posted all those porno pictures to Usenet and it never would have grown beyond its discussion board roots

Ken

p.s. Perhaps I should use yenc. I remember when that hit Usenet. What a stink!

jpollard · 03-30-2021, 09:36 AM

Quote:

Originally Posted by taylorkh

Thanks again shruggy,

I see the original file name in the "output" file when I try to redirect the outputproduces

Code:

begin-base64 664 Greta_Granstedt.jpg
====

Something strange is going on.

Ken

How about:

Code:

uuencode -m Greta_Granstedt.jpg <Greta_Granstedt.jpg > Greta.uu

taylorkh · 03-30-2021, 11:06 AM

Congratulations jpollard - you win the prize!

That did the trick. I then tried

Code:

uuencode -m George.jpg <Greta_Granstedt.jpg > Greta.uu

and it created the first line of the Greta.uu file as

Code:

begin-base64 664 George.jpg

so the first item specified in the command is not related to the file being converted nor the file being created. Is this obvious from the man page? Not to me

Actually I think I may have found the root cause of my confusion. Again from the man page

Code:

NOTES
       This manual page was AutoGen-erated from the uuencode option definitions.

Thank you for sticking with this.

Ken

jpollard · 03-31-2021, 01:42 AM

Thanks.

It has been a LONG time since I used uuencode/uudecode. This and shruggy's last comment reminded me of the original intent of uuencode/uudecode as used with uucp.

And the implementation HAS changed. Originally the file name was supposed to be the input file and optional - if missing it processed stdin, and a second name was the name (mandatory) used for the file when uudecode was used.

For some reason the "file" parameter is currently being ignored.

I found this as the OLD documentation... which is what you interpreted the current manpage to be meaning (I did too when I first read it again), and forgot the "file label" name now identified as the "decode_pathname"

http://cng.seas.rochester.edu/CNG/do.../uuencode.html