HEXDUMP(1)

👑 HEXDUMP(1) — the hexdump / hd glow-up guide 💅

User Commands · part 1 of 2, bestie, we're going on a journey

---

✨ NAME ✨

hexdump — display file contents in hexadecimal, decimal, octal, or ascii 🦋

---

✨ SYNOPSIS ✨

hexdump [options] file ...

hd [options] file ...

---

✨ DESCRIPTION ✨

okay so. the hexdump utility is a filter 💖 it shows you the files you named — or standard input if you named no files at all — in a format you get to pick. yes you. main character energy. 👑

---

🌈 OPTIONS 🌈

first things first, a little lore drop 🧚: down below, the length and offset arguments can be followed by multiplicative suffixes — KiB (=1024), MiB (=1024*1024), and so on for GiB, TiB, PiB, EiB, ZiB and YiB (the "iB" is optional, so like "K" means the exact same thing as "KiB" 💫). OR you can use KB (=1000), MB (=1000*1000), and so on for GB, TB, PB, EB, ZB and YB. slay, units.

• -b, --one-byte-octal — One-byte octal display. Shows the input offset in hexadecimal, then sixteen space-separated, three-column, zero-filled bytes of input data, in octal, per line. ✨
• -X, --one-byte-hex — One-byte hexadecimal display. Shows the input offset in hexadecimal, then sixteen space-separated, two-column, zero-filled bytes of input data, in hexadecimal, per line.
• -c, --one-byte-char — One-byte character display. Shows the input offset in hexadecimal, then sixteen space-separated, three-column, space-filled characters of input data per line.
• -C, --canonical — Canonical hex+ASCII display. Shows the input offset in hexadecimal, then sixteen space-separated, two-column, hexadecimal bytes, then those same sixteen bytes in %_p format wrapped in | characters. 🫶 also — if you invoke the program as hd, it implies this option. iykyk.
• -d, --two-bytes-decimal — Two-byte decimal display. Shows the input offset in hexadecimal, then eight space-separated, five-column, zero-filled, two-byte units of input data, in unsigned decimal, per line.
• -e, --format format_string — Specify a format string to be used for displaying data.
• -f, --format-file file — Specify a file that contains one or more newline-separated format strings. Empty lines and lines whose first non-blank character is a hash mark (#) are ignored. 🎀
• -L, --color[=when] — Accept color units for the output. The optional argument when can be auto, never or always. If the when argument is omitted, it defaults to auto. The colors can be disabled; for the current built-in default see the --help output. See also the Colors subsection and the COLORS section below. 🌈
• -n, --length length — Interpret only length bytes of input.
• -o, --two-bytes-octal — Two-byte octal display. Shows the input offset in hexadecimal, then eight space-separated, six-column, zero-filled, two-byte quantities of input data, in octal, per line.
• -s, --skip offset — Skip offset bytes from the beginning of the input.
• -v, --no-squeezing — The -v option causes hexdump to display all input data. Without -v, any number of groups of output lines which would be identical to the immediately preceding group of output lines (except for the input offsets) are replaced with a line comprised of a single asterisk. 👀 (yes the famous *, she's iconic)
• -x, --two-bytes-hex — Two-byte hexadecimal display. Shows the input offset in hexadecimal, then eight space-separated, four-column, zero-filled, two-byte quantities of input data, in hexadecimal, per line.
• -h, --help — Display help text and exit.
• -V, --version — Display version and exit.

For each input file, hexdump sequentially copies the input to standard output, transforming the data according to the format strings specified by the -e and -f options, in the order that they were specified. 💜 order matters bestie, it's giving choreography.

---

✨ FORMATS ✨

A format string contains any number of format units, separated by whitespace. A format unit contains up to three items: an iteration count, a byte count, and a format. 🧚

The iteration count is an optional positive integer, which defaults to one. Each format is applied iteration count times.

The byte count is an optional positive integer. If specified, it defines the number of bytes to be interpreted by each iteration of the format.

If an iteration count and/or a byte count is specified, a single slash must be placed after the iteration count and/or before the byte count to disambiguate them. Any whitespace before or after the slash is ignored. 🎀

The format is required and must be surrounded by double quote (" ") marks. It is interpreted as a fprintf-style format string (see fprintf(3)), with the following exceptions:

1. An asterisk (*) may not be used as a field width or precision.
2. A byte count or field precision is required for each s conversion character (unlike the fprintf(3) default which prints the entire string if the precision is unspecified).
3. The conversion characters h, l, n, p, and q are not supported. 💀
4. The single character escape sequences described in the C standard are supported:

\0   NULL
\a   alert character
\b   backspace
\f   form-feed
\n   newline
\r   carriage return
\t   tab
\v   vertical tab

✨ Conversion strings ✨

The hexdump utility also supports the following additional conversion strings. obsessed.

• _a[dox] — Display the input offset, cumulative across input files, of the next byte to be displayed. The appended characters d, o, and x specify the display base as decimal, octal or hexadecimal respectively.
• _A[dox] — Almost identical to the _a conversion string except that it is only performed once, when all of the input data has been processed. 🦋
• _c — Output characters in the default character set. Non-printing characters are displayed in three-character, zero-padded octal, except for those representable by standard escape notation (see above), which are displayed as two-character strings.
• _p — Output characters in the default character set. Non-printing characters are displayed as a single ..
• _u — Output US ASCII characters, with the exception that control characters are displayed using the following, lower-case, names. Characters greater than 0xff, hexadecimal, are displayed as hexadecimal strings.

00 nul     08 bs      10 dle     18 can     7F del
01 soh     09 ht      11 dc1     19 em
02 stx     0A lf      12 dc2     1A sub
03 etx     0B vt      13 dc3     1B esc
04 eot     0C ff      14 dc4     1C fs
05 enq     0D cr      15 nak     1D gs
06 ack     0E so      16 syn     1E rs
07 bel     0F si      17 etb     1F us

✨ Colors ✨

When put at the end of a format specifier, hexdump highlights the respective string with the color specified. Conditions, if present, are evaluated prior to highlighting. 💅

_L[color_unit_1,color_unit_2,...,color_unit_n]

The full syntax of a color unit is as follows:

[!]COLOR[:VALUE][@OFFSET_START[-END]]

• ! — Negate the condition. Please note that it only makes sense to negate a unit if both a value/string and an offset are specified. In that case the respective output string will be highlighted if and only if the value/string does not match the one at the offset. 🙈
• COLOR — One of the 8 basic shell colors.
• VALUE — A value to be matched specified in hexadecimal, or octal base, or as a string. Please note that the usual C escape sequences are not interpreted by hexdump inside the color_units. ⚠️
• OFFSET — An offset or an offset range at which to check for a match. Please note that lone OFFSET_START uses the same value as END offset.

✨ Counters ✨

The default and supported byte counts for the conversion characters are as follows:

• %_c, %_p, %_u, %c — One byte counts only.
• %d, %i, %o, %u, %X, %x — Four byte default, one, two and four byte counts supported.
• %E, %e, %f, %G, %g — Eight byte default, four byte counts supported.

The amount of data interpreted by each format string is the sum of the data required by each format unit, which is the iteration count times the byte count, or the iteration count times the number of bytes required by the format if the byte count is not specified.

The input is manipulated in blocks, where a block is defined as the largest amount of data specified by any format string. Format strings interpreting less than an input block's worth of data, whose last format unit both interprets some number of bytes and does not have a specified iteration count, have the iteration count incremented until the entire input block has been processed or there is not enough data remaining in the block to satisfy the format string. 😮‍💨 she's doing math but make it cute.

If, either as a result of user specification or hexdump modifying the iteration count as described above, an iteration count is greater than one, no trailing whitespace characters are output during the last iteration.

It is an error to specify a byte count as well as multiple conversion characters or strings unless all but one of the conversion characters or strings is _a or _A. 🚨

If, as a result of the specification of the -n option or end-of-file being reached, input data only partially satisfies a format string, the input block is zero-padded sufficiently to display all available data (i.e., any format units overlapping the end of data will display some number of the zero bytes). 🌸

Further output by such format strings is replaced by an equivalent number of spaces. An equivalent number of spaces is defined as the number of spaces output by an s conversion character with the same field width and precision as the original conversion character or conversion string but with any '+', ' ', '#' conversion flag characters removed, and referencing a NULL string.

If no format strings are specified, the default display is very similar to the -x output format (the -x option causes more space to be used between format units than in the default output). ⭐

Note that the default format and the -x, -d, and -o options use multi-byte format units that are displayed in the system's native byte order (endianness). This means the same input may produce different output on little-endian (e.g., x86, ARM64) and big-endian (e.g., s390x) systems. For byte-order independent output, use single-byte formats such as -b, -c, -C, or -X. 🌍💖

---

✨ EXIT STATUS ✨

hexdump exits 0 on success and > 0 if an error occurred. 🎀

---

✨ CONFORMING TO ✨

The hexdump utility is expected to be IEEE Std 1003.2 ("POSIX.2") compatible. 👑

---

✨ EXAMPLES ✨

okay bestie, this is the part where it gets fun. here's how you actually use all those format strings you just read about 💖

---

🌸 Display the input in perusal format 🌸

this one gives you the classic look, like hexdump -C but you're building it yourself:

"%06.6_ao "  12/1 "%3_u "
"\t" "%_p "
"\n"

that's offset, then twelve bytes each padded into three chars, then a tab, then the printable chars, then a newline. chef's kiss. 💅

---

🦋 Implement the -x option 🦋

yes literally this is just what -x does, you can rebuild it yourself:

"%07.7_Ax\n"
"%07.7_ax  " 8/2 "%04x " "\n"

seven-digit address, uppercase hex, newline, then the address again in lowercase with two spaces, then eight groups of two bytes rendered as four-digit hex, then a line break. iconic. ✨

---

👑 MBR Boot Signature example 👑

this is the fancy one, and it's giving main character energy: highlight the addresses cyan and the bytes at offsets 510 and 511 green if their value is 0xAA55, red otherwise.

"%07.7_Ax_L[cyan]\n"
"%07.7_ax_L[cyan]  " 8/2 "   %04x_L[green:0xAA55@510-511,!red:0xAA55@510-511] " "\n"

see that conditional color syntax? _L[green:0xAA55@510-511,!red:0xAA55@510-511] — green when those bytes match, red when they don't. literally the boot signature getting a whole color-coded glow-up 🎀

---

🎨 COLORS 🎨

the output colorization is implemented by terminal-colors.d(5) functionality, which is the whole system for telling your tools what colors to use. 🌈

implicit coloring can be disabled by an empty file

/etc/terminal-colors.d/hexdump.disable

if you just want to kill it for the hexdump command specifically, or for all tools with

/etc/terminal-colors.d/disable

since version 2.41, the $NO_COLOR environment variable is also supported to disable output colorization unless explicitly enabled by a command-line option. so like, $NO_COLOR is the vibe killer but a CLI flag can override it, iykyk. 💀

the user-specific $XDG_CONFIG_HOME/terminal-colors.d or $HOME/.config/terminal-colors.d overrides the global setting. your personal config wins, always. 👑

note that the output colorization may be enabled by default, and in this case terminal-colors.d directories do not have to exist yet. so don't panic if you don't see the folder, bestie, the colors are still coming 🫶

---

😭 REPORTING BUGS 😭

found a bug? for bug reports, use the issue tracker <https://github.com/util-linux/util-linux/issues>.

(be nice in the issue, okay? maintainers are people too 💜)

---

📦 AVAILABILITY 📦

the hexdump command is part of the util-linux package which can be downloaded from Linux Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.

---

and that's the whole page, bestie!! 🎉 you're now fully certified in hexdump lore. this was util-linux 2.42.4, dated 2026-09-21, HEXDUMP(1) — go forth and dump some hex, you absolute legend 💖✨🌸🦋💅