bash ascii to hex

Question

was wondering if anyone could help me with converting ascii to hex in bash. Example code:

#!/bin/bash 
STR = "hello"
#Convert to hex
HEXVAL = $STR #(in hex here?)

I want hexval to have the value: 68656C6C6F (hello in hex)

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possible dupe of http://stackoverflow.com/questions/5724761/ascii-hex-convert-in-bash — mrchampe, Oct 11 '12 at 19:57

John Kugelman · Accepted Answer · 2023-03-03T04:16:00.390

50

$ str="hello"
$ hex="$(printf '%s' "$str" | xxd -p -u)"
$ echo "$hex"
68656C6C6F

Or:

$ hex="$(printf '%s' "$str" | hexdump -ve '/1 "%02X"')"
$ echo "$hex"
68656C6C6F

Careful with the '"%X"'; it has both single quotes and double quotes.

edited Mar 03 '23 at 04:16

answered Oct 11 '12 at 19:50

John Kugelman

349,597
67
533
578

1

On `xxd V1.10 27oct98`, I have to use `xxd -p -u`. – mja Apr 10 '18 at 10:06
"xxd -pu" worked for me, but I thought I'd mention that the other suggestion had an entirely different output. – Serge Apr 26 '22 at 09:37
hexdump reads by 4 bites so the "6C6C6568A6F" is incorrect. It is "lleho" – Hedgehog Mar 02 '23 at 21:41
@Hedgehog Wow, and yikes! I've fixed both examples. – John Kugelman Mar 03 '23 at 04:16

score 11 · Answer 2 · edited May 23 '17 at 11:54

11

You have several options

$ printf hello | xxd
0000000: 6865 6c6c 6f                             hello

See also: Ascii/Hex convert in bash

edited May 23 '17 at 11:54

Community

1
1

answered Oct 11 '12 at 19:56

mrchampe

452
3
12

makarevs · Answer 3 · 2018-02-08T13:37:04.473

4

Pure BASH convertor of string to printable hexadecimal sequence and back

str2hex_echo() {
    # USAGE: hex_repr=$(str2hex_echo "ABC")
    #        returns "0x410x420x43"
    local str=${1:-""}
    local fmt="0x%x"
    local chr
    local -i i
    for i in `seq 0 $((${#str}-1))`; do
        chr=${str:i:1}
        printf  "${fmt}" "'${chr}"
    done
}

hex2str_echo() {
    # USAGE: ASCII_repr=$(hex2str_echo "0x410x420x43")
    #        returns "ABC"
    echo -en "'${1:-""//0x/\\x}'"
}

EXPLANATION

ASCII->hex: The secret sauce of efficient conversion from character to its underlying ASCII code is feature in printf that, with non-string format specifiers, takes leading character being a single or double quotation mark as an order to produce the underlying ASCII code of the next symbol. This behavior is documented in GNU BASH reference, but is also exposed in details together with many other other wonderful utilities in Greg's (also known as GreyCat's) wiki page BashFAQ/071 dedicated to char-ASCII conversions.

edited Feb 08 '18 at 13:37

answered Feb 08 '18 at 12:21

makarevs

41
2

Using "seq" is not pure-bash! But I have a simplified "seq" function written in pure-bash :-) – anthony Feb 18 '20 at 03:16
Why use `seq`? Why not just `for ((i = 0; i < ${#str}; ++i))`? – Chris Page Jul 15 '20 at 02:02
Why use `fmt` instead of putting the format string inline? e.g., `printf '0x%x' "'${chr}"` – Chris Page Jul 15 '20 at 02:04
This will now fail due to unicode character handling... which come out as utf16 hex codes. – anthony Oct 13 '20 at 00:56

score 1 · Answer 4 · answered Jan 19 '14 at 10:32

1

here's a one liner (a little complex but works fine):

#!/bin/bash

echo '0x'"`echo $1 | hexdump -vC |  awk 'BEGIN {IFS="\t"} {$1=""; print }' | awk '{sub(/\|.*/,"")}1'  | tr -d '\n' | tr -d ' '`" | rev | cut -c 3- | rev

answered Jan 19 '14 at 10:32

blogresponder

43
3

score 1 · Answer 5 · answered Feb 18 '20 at 03:15

1

xxd -p -u <<< "$STR" | sed 's/\(..\)/0x&, /g; s/, $//;'

0x68, 0x65, 0x6C, 0x6C, 0x6F, 0x0A

answered Feb 18 '20 at 03:15

anthony

7,696
1
17
11

storenth · Answer 6 · 2023-02-27T02:40:00.393

0

Only hex line output. Tested, both systems verified.

# Linux
$ echo -n 'hello' | hexdump -ve '/1 "%02x"'
68656c6c6f

# Mac
$ echo -n 'hello' | xxd -p -c 256
68656c6c6f

edited Feb 27 '23 at 02:40

answered Dec 21 '21 at 05:26

storenth

967
11
18

`0a` should not be at the end of the string. – deweydb Feb 15 '23 at 17:28
@deweydb how to rewrite my solution?) – storenth Feb 16 '23 at 16:36
1

try `echo -n 'hello' | hexdump -ve '/1 "%02x"'` and `echo -n 'hello' | xxd -p -c 256` https://linux.die.net/man/1/echo – deweydb Feb 17 '23 at 18:35

score 0 · Answer 7 · answered Dec 11 '22 at 12:44

POSIX option

I think this one is POSIX:

od-raw() {
  od -A n -t x1 -v | tr -d ' \n' 
}

Usage:

printf hello | od-raw

Output:

68656c6c6f

Or if you want separating spaces:

os-raw-spaces() {
  od -A n -t x1 -v "$@" | tr -d '\n' | cut -c 2-
}

Output:

68 65 6c 6c 6f

Tested on Ubuntu 22.04.

How to create a hex dump of file containing only the hex characters without spaces in bash?

bash ascii to hex

7 Answers7

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