Re: base64 terminal input failure

[Bob Proulx]

e-letter wrote:
> I have tried to copy base64 encoded text from the clipboard (i.e. a
> web mail message) to the command terminal:
> 
> base64 -d 'xyz'
> 
> where 'xyz' is the base64 text. According to the manual, standard
> input can be accepted if a file is not accepted but instead the
> terminal response is:
> 
> base64: xyz: No such file or directory
> 
> What is my mistake please?

The base64 syntax is:

  base64 [OPTION]... [FILE]

You have specified one option and what appears to the command to be
one file.  The -d fits in the [OPTION] spot and the xyz fits in the
[FILE] spot.

The brackets indicate that those parts are optional.  For [OPTIONS] no
options means to encode.  Specifying -d means to decode.

For [FILE] this means that if a file is specified then the command
will open the file and read it.  If no file is specified on the
command line then it will read standard input.

> The command:
> 'echo xyz | base64 -d'
> 
> returns:
> �,base64: invalid input
> 
> If the base64 text is saved as a file, conversion is successful.

This is because "xyz" isn't valid base64 encoded data.  It works
successfully if you give it valid input data instead of random
characters.  See this example:

  $ echo foo | base64
  Zm9vCg==

  $ echo foo | base64 | base64 -d
  foo

  $ echo Zm9vCg== | base64 -d
  foo

As you can see if the input is valid then it will decode it correctly.

Bob