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Old 09-30-2006, 09:01 PM   #1
//////
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[bash] ASCII to HEX and hex to ascii


What kind of command should I use to translate ascii to hex in a bash script ? (and hex back to ascii)

TIA

/////
 
Old 09-30-2006, 09:30 PM   #2
paulsm4
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do you mean something like this?
Code:
echo 0x41 | awk '{printf "%c\n", $1}'
A
The other direction (like an "ord(char)" function), is much less straightforward. Here are a couple of interesting solutions:

http://devworld.apple.com/documentat...section_3.html

And here's yet another possibility:
Code:
echo A|hexdump
0000000 0a41
0000002
... or, equivalently ...
Code:
echo A|od -x
0000000 0a41
0000002

Last edited by paulsm4; 09-30-2006 at 09:42 PM.
 
Old 09-30-2006, 09:53 PM   #3
//////
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Hi, yes something like that. Only but is that..
Code:
echo 0x41 | awk '{printf "%c\n", $1}'
0
..this doesn't work in my box
awk -W version
GNU Awk 3.1.5
Code:
awk '{printf "%c\n", $1}' /root/Desktop/testfile # testfile contains 0x41
0
it woold be good if it worked with words, not just single letters.

Cheers

////

Edit: Thank you, I can use that hexdump, and that link is a nice one

Last edited by //////; 09-30-2006 at 10:07 PM.
 
Old 10-01-2006, 08:48 AM   #4
spirit receiver
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Quote:
Originally Posted by //////
..this doesn't work in my box
Try the following instead (with Bash):
Code:
ada@barnabas:~> echo -e "\x41" | awk '{printf "%c\n", $1}'
A
Edit: Sorry, I guess this is nonsense.

Last edited by spirit receiver; 10-01-2006 at 08:56 AM.
 
Old 10-01-2006, 09:50 AM   #5
ghostdog74
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alternative in Python:

ascii to hex:

Code:
#!/usr/bin/python
hex(ord('a'))
output:
'0x61'

hex to ascii
Code:
import binascii
binascii.a2b_hex("61")
output:
'a'
 
Old 10-01-2006, 10:12 AM   #6
spirit receiver
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... and I just learned that there's a package named uni2ascii which does the following:
Code:
ada@barnabas:~> echo "ABCDE" | uni2ascii -Bsepq
\x0041\x0042\x0043\x0044\x0045
ada@barnabas:~> echo "ABCDE" | uni2ascii -Bsepq | ascii2uni -Bq
ABCDE
 
Old 10-01-2006, 10:55 AM   #7
//////
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Quote:
Originally Posted by spirit receiver
... and I just learned that there's a package named uni2ascii which does the following:
Code:
ada@barnabas:~> echo "ABCDE" | uni2ascii -Bsepq
\x0041\x0042\x0043\x0044\x0045
ada@barnabas:~> echo "ABCDE" | uni2ascii -Bsepq | ascii2uni -Bq
ABCDE
Thanks guys, that uni2ascii is a good one, just compiled it and it does its job nicely.
 
Old 10-01-2006, 12:18 PM   #8
osor
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There's a nice utility that comes with Vim called xxd. It is script-friendly, and (unlike od or hexdump) has the ability to go back and forth (with the revert option).

For example, you could have something like:
Code:
... | xxd -g 1 -c 1 | awk ...
Where there are three fields you can access in awk. $1 is the offset (in hex), $2 is the two-digit hex representation of a byte, and $3 is the ASCII representation of the byte (or just a period for nonprintable characters).

For going back, just do something like:
Code:
... | xxd -p -s -
The only formatting restrictions on the input is that single bytes appear together as two-digit numbers. It doesn't care about formatting or whitespace (the -p is for plain).

I guess xxd's not as portable as hexdump or od, but it is probably more portable than uni2ascii (i.e., is more likely to be found installed on a *nix machine than uni2ascii).
 
Old 10-01-2006, 12:44 PM   #9
//////
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Quote:
Originally Posted by osor
I guess xxd's not as portable as hexdump or od, but it is probably more portable than uni2ascii (i.e., is more likely to be found installed on a *nix machine than uni2ascii).
Thats true, but I'm not that concerned about portability, (I'm using slax based Back|Track and adding modules is easy) and I'm not doing anything really important, just learning to write my own snort rules and I was getting tired to visit online hex translators

But anyways, that ascii2hex is working nicely with my script so thanks again.

Code:
slax ~ # /root/Desktop/trans 'Hello there !'
48 65 6C 6C 6F 20 74 68 65 72 65 20 21
 
Old 06-14-2010, 07:48 PM   #10
gsm123
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Another awk alternative with more than one character

Code:
echo -e "\x41\x20\x42\x20\x43" | awk '{printf "%s\n", $_}'
gives

Quote:
A B C
 
Old 05-13-2013, 10:31 AM   #11
SPF
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What if your string is:
48656C6C6F2074686572652021

And you don't have perl, python, xxd or uni2ascii?
And you are not allowed to install it.

How can you convert it?

Or course I could always write a loop and read it in pairs:

Code:
#!/bin/bash
function hex2string () {
  I=0
  while [ $I -lt ${#1} ];
  do
    echo -en "\x"${1:$I:2}
    let "I += 2"
  done
}
hex2string "48656C6C6F2074686572652021"
 
Old 05-15-2013, 03:26 PM   #12
David the H.
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Hex to ascii is dead easy; bash can do it internally, if they're properly formatted. Just use "echo -e", printf's %b format token, or the $'..' quoting form. See the sections on QUOTING and the echo built-in in the bash man page for full details on what these options can expand.

So in post #10 above, the awk command is actually completely superfluous. The characters are converted by echo before they even reach it.

As for the reverse direction, there's no built-in way to do it, so see the above. I've also used uniname before to get the hex codes of a string of characters.

Edit: Example use for the string in #9:

Code:
$ hexchars=( 48 65 6C 6C 6F 20 74 68 65 72 65 20 21 )
$ ( IFS='' ; printf '%b\n' "${hexchars[*]/#/\x}" )
Hello there !
I used a '(..)' subshell in order to keep the IFS setting local. It's needed in order to print the '*' expansion without spaces between each entry. Changing '*' to '@' would print every character on a separate line.

Last edited by David the H.; 05-15-2013 at 03:36 PM. Reason: as stated
 
Old 06-02-2013, 05:50 PM   #13
peetaur
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You guys with awk are silly... your awk is not doing anything at all. Sorry to point that out. :P

Code:
$ echo -e "\x41\x20\x42\x20\x43" |cat
A B C
$ echo -e "\x41\x20\x42\x20\x43" | awk '{printf "%s\n", $_}'
A B C
 
Old 03-20-2014, 11:21 AM   #14
es131245
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Code:
#!/bin/sh
echo -e "\x41\x20\x42\x20\x43" | cat
echo -e "\x41\x20\x42\x20\x43" | awk '{printf "%s\n", $_}'
exit
Code:
"try.sh" 25 lines, 893 characters
\x41\x20\x42\x20\x43
awk: illegal field $(), name "_"
 input record number 1, file 
 source line number 1
Code:
uname -a
FreeBSD host.com 10.0-RELEASE FreeBSD 10.0-RELEASE #0 r260789: Thu Jan 16 22:34:59 UTC 2014     root@snap.freebsd.org:/usr/obj/usr/src/sys/GENERIC  amd64

Last edited by es131245; 03-22-2014 at 03:59 AM.
 
Old 03-20-2014, 01:43 PM   #15
suicidaleggroll
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Quote:
Originally Posted by es131245 View Post
Code:
#!/bin/sh
echo -e "\x41\x20\x42\x20\x43" | cat
echo -e "\x41\x20\x42\x20\x43" | awk '{printf "%s\n", $_}'
exit
Code:
"try.sh" 25 lines, 893 characters
\x41\x20\x42\x20\x43
awk: illegal field $(), name "_"
 input record number 1, file 
 source line number 1
Code:
uname -a
FreeBSD y-es.ru 10.0-RELEASE FreeBSD 10.0-RELEASE #0 r260789: Thu Jan 16 22:34:59 UTC 2014     root@snap.freebsd.org:/usr/obj/usr/src/sys/GENERIC  amd64
Works fine for me with both bash and sh. It looks to me like you have an outdated version of awk that doesn't support "$_", but I have no experience with FreeBSD. I'm running GNU awk 3.1.8

Last edited by suicidaleggroll; 03-20-2014 at 01:44 PM.
 
  


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