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xxd

Practical xxd usage for hex dumping, binary inspection, firmware and EFI variable analysis, random data generation, ASCII↔hex conversion, and reverse reconstruction workflows

View hex mode in vim

:%!xxd

Geberate 30x30 matrix

xxd -p /dev/urandom |fold -60|head -30|sed 's/\(..\)/\1 /g'

Convert ascii string to hex

xxd -p <<< <string>

Convert ascii string to hex

echo -n 'text' | xxd -ps | sed -e ':a' -e 's/\([0-9]\{2\}\|^\)\([0-9]\{2\}\)/\1\\x\2/;ta'

Generate a 20-byte random hex string from /dev/urandom

xxd -l 20 -p /dev/urandom

Print exactly 20 bytes → 40 hex chars on one line

xxd -l 20 -p -c 40 /dev/urandom

Read output with 200 columns rather den default

xxd -g 1 -c 200 /sys/firmware/dmi/tables/DMI | head -n5

Hexdump the DMI table with byte-level grouping and wide output (200 columns)

xxd -g 1 -c 200 /sys/firmware/dmi/tables/DMI

Extract ASCII columns for 200 bytes lines

xxd -g 1 -c 200 /sys/firmware/dmi/tables/DMI \
| sed -E 's/^.*  //' \
| tr -cd '[:print:]\n'

Read our BootOrder file in efivars

xxd -g 4 /sys/firmware/efi/efivars/BootOrder-8be4df61-93ca-11d2-aa0d-00e098032b8c
00000000: 07000000 04000000                    ....

Read bios rom exposed via sysfs (raw dump preview)

xxd -g 1 -c 128 /sys/firmware/dmi/tables/DMI | head -n10

Read legacy bios memory region via /dev/mem (first 1 KB)

dd if=/dev/mem bs=1 count=1024 skip=$((0xF0000)) 2>/dev/null | xxd -g 1

Read option rom area from /dev/mem (C0000h VGA ROM)

dd if=/dev/mem bs=1 count=512 skip=$((0xC0000)) 2>/dev/null | xxd -g 1

Read EFI BootCurrent variable (hex + ASCII)

xxd -g 2 /sys/firmware/efi/efivars/BootCurrent-8be4df61-93ca-11d2-aa0d-00e098032b8c

Read EFI SecureBoot state

xxd -g 1 /sys/firmware/efi/efivars/SecureBoot-8be4df61-93ca-11d2-aa0d-00e098032b8c

Read EFI SetupMode flag

xxd -g 1 /sys/firmware/efi/efivars/SetupMode-8be4df61-93ca-11d2-aa0d-00e098032b8c

Inspect raw EFI variable payload (skip attributes)

xxd -g 1 -s 4 /sys/firmware/efi/efivars/BootOrder-8be4df61-93ca-11d2-aa0d-00e098032b8c

Read a binary firmware blob

xxd -g 1 -c 64 firmware.bin | head -n20

Compare two binary files visually

diff <(xxd -g 1 fileA.bin) <(xxd -g 1 fileB.bin)

Reverse hex dump back into binary

xxd -r dump.hex restored.bin

Matrix style (red color)

xxd -p -c1 /dev/urandom \
| awk -v cols="${COLUMNS:-$(tput cols)}" '{b=strtonum("0x"$1); printf (b%8?" ":"%c",48+(b%10)); if(++n%cols==0) print ""}' \
| grep --color=always '[0-9]'

Matrix style (colorless)

xxd -p -c1 /dev/urandom \
| awk -v cols="${COLUMNS:-$(tput cols)}" '{b=strtonum("0x"$1); printf (b%8?" ":"%c",48+(b%10)); if(++n%cols==0) print ""}'

Matrix style (random colors)

xxd -p -c1 /dev/urandom \
| awk -v cols="${COLUMNS:-$(tput cols)}" '
BEGIN {
  split("31 32 33 34 35 36 37 90 92 93 94 95 96", C)
}
{
  b = strtonum("0x"$1)
  if (b % 8) {
    printf " "
  } else {
    color = C[int(rand()*length(C))+1]
    printf "\033[%sm%c\033[0m", color, 48+(b%10)
  }
  if (++n % cols == 0) printf "\n"
}'