A hexdumper using echo only... Post: 302931163

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Top Forums UNIX for Advanced & Expert Users A hexdumper using echo only... Post 302931163 by wisecracker on Sunday 11th of January 2015 08:55:06 AM

01-11-2015

Registered User

Hi sea..

Not quite sure what you are doing as a newline character is difficult to __read__ using read.

Binary 0, (zero), is another difficult task along with tab and space. Tab and space are relatively easy but binary 0x00 and 0x0A using echo was NOT at all easy. It IS now though... ;oD

With the printf command things become relatively simple and binary can be read into HEX values with relative ease.

BUT, and this is a big but, echo is a different animal when printf does NOT exist.

The echo commands ARE needed to transfer trenslated data into say another file or into a variable. Translating a binary file to HEX is seriously difficult using just the echo command so brute force was really the only way using part of the filenames as the HEX value, by comparing the real binaries against the contents of these filenames... <wink>

I am still technically a novice at shell scripting but my pet love is handling pure binary and banging the metal and I consider myself semi-pro at this level.

This was promoted from beginners to advanced by one of the big guns on here and might be worth a read about binary 0x00:-

Another binary manipulation thread.

wisecracker

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LEARN ABOUT OSX

echo

ECHO(1) 						    BSD General Commands Manual 						   ECHO(1)

NAME

     echo -- write arguments to the standard output

SYNOPSIS

     echo [-n] [string ...]

DESCRIPTION

     The echo utility writes any specified operands, separated by single blank (' ') characters and followed by a newline ('
') character, to the
     standard output.

     The following option is available:

     -n    Do not print the trailing newline character.  This may also be achieved by appending 'c' to the end of the string, as is done by iBCS2
	   compatible systems.	Note that this option as well as the effect of 'c' are implementation-defined in IEEE Std 1003.1-2001
	   (``POSIX.1'') as amended by Cor. 1-2002.  Applications aiming for maximum portability are strongly encouraged to use printf(1) to sup-
	   press the newline character.

     Some shells may provide a builtin echo command which is similar or identical to this utility.  Most notably, the builtin echo in sh(1) does
     not accept the -n option.	Consult the builtin(1) manual page.

EXIT STATUS

     The echo utility exits 0 on success, and >0 if an error occurs.

SEE ALSO

     builtin(1), csh(1), printf(1), sh(1)

STANDARDS

     The echo utility conforms to IEEE Std 1003.1-2001 (``POSIX.1'') as amended by Cor. 1-2002.

BSD
								  April 12, 2003							       BSD

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