DD(1)

📦 version 0.12.0, in arch rolling

🌸 NAME 🌸

okay so welcome to DD(1), straight out of the General Commands Manual — this is the dd page, and she copies, and optionally converts, a file system resource. main character copy tool energy, fr fr. 💖

✨ SYNOPSIS ✨

dd [OPERAND]...
dd OPTION

💖 DESCRIPTION 💖

copy, and optionally convert, a file system resource. that's the vibe. no cap. 🫶

🎀 OPTIONS 🎀

  • -h, --help — print help, bestie.
  • -V, --version — print version.
  • [operands] — okay so the actual operands are a whole moment. they live in the EXTRA section below, and yes every single one is there. 💅

🦋 EXTRA 🦋

okay bestie, this is the big one — all the operands, conversion options, input flags, output flags, and general flags. i kept every single one. no skips, no "you'll figure it out." periodt. ✨

🍓 Operands 🍓

  • bs=BYTES — read and write up to BYTES bytes at a time (default: 512); overwrites ibs and obs. she's the boss of both buffer sizes, lowkey.
  • cbs=BYTES — the 'conversion block size' in bytes. applies to the conv=block and conv=unblock operations.
  • conv=CONVS — a comma-separated list of conversion options or (for legacy reasons) file flags. yes, file flags too, for legacy reasons. iconic.
  • count=N — stop reading input after N ibs-sized read operations rather than proceeding until EOF. see iflag=count_bytes if stopping after N bytes is preferred. 💡
  • ibs=N — the size of buffer used for reads (default: 512).
  • if=FILE — the file used for input. when not specified, stdin is used instead.
  • iflag=FLAGS — a comma-separated list of input flags which specify how the input source is treated. FLAGS may be any of the input-flags or general-flags specified below.
  • skip=N (or iseek=N) — skip N ibs-sized records into input before beginning copy/convert operations. see iflag=seek_bytes if seeking N bytes is preferred.
  • obs=N — the size of buffer used for writes (default: 512).
  • of=FILE — the file used for output. when not specified, stdout is used instead.
  • oflag=FLAGS — comma separated list of output flags which specify how the output source is treated. FLAGS may be any of the output flags or general flags specified below.
  • seek=N (or oseek=N) — seeks N obs-sized records into output before beginning copy/convert operations. see oflag=seek_bytes if seeking N bytes is preferred.
  • status=LEVEL — controls whether volume and performance stats are written to stderr.

when unspecified, dd will print stats upon completion. an example is below.

6+0 records in
16+0 records out
8192 bytes (8.2 kB, 8.0 KiB) copied, 0.00057009 s,
14.4 MB/s

the first two lines are the 'volume' stats and the final line is the 'performance' stats. the volume stats indicate the number of complete and partial ibs-sized reads, or obs-sized writes that took place during the copy. the format of the volume stats is <complete>+<partial>. if records have been truncated (see conv=block), the volume stats will contain the number of truncated records.

Possible LEVEL values are:

  • progress — print periodic performance stats as the copy proceeds.
  • noxfer — print final volume stats, but not performance stats.
  • none — do not print any stats.

printing performance stats is also triggered by the INFO signal (where supported), or the USR1 signal. setting the POSIXLY_CORRECT environment variable to any value (including an empty value) will cause the USR1 signal to be ignored. 🙈

💅 Conversion options 💅

  • ascii — convert from EBCDIC to ASCII. this is the inverse of the ebcdic option. implies conv=unblock.
  • ebcdic — convert from ASCII to EBCDIC. this is the inverse of the ascii option. implies conv=block.
  • ibm — convert from ASCII to EBCDIC, applying the conventions for [, ] and ~ specified in POSIX. implies conv=block.
  • ucase — convert from lower-case to upper-case.
  • lcase — convert from upper-case to lower-case.
  • block — for each newline less than the size indicated by cbs=BYTES, remove the newline and pad with spaces up to cbs. lines longer than cbs are truncated.
  • unblock — for each block of input of the size indicated by cbs=BYTES, remove right-trailing spaces and replace with a newline character.
  • sparse — attempts to seek the output when an obs-sized block consists of only zeros.
  • swab — swaps each adjacent pair of bytes. if an odd number of bytes is present, the final byte is omitted.
  • sync — pad each ibs-sided block with zeros. if block or unblock is specified, pad with spaces instead.
  • excl — the output file must be created. fail if the output file is already present.
  • nocreat — the output file will not be created. fail if the output file is not already present.
  • notrunc — the output file will not be truncated. if this option is not present, output will be truncated when opened. 👀
  • noerror — all read errors will be ignored. if this option is not present, dd will only ignore Error::Interrupted.
  • fdatasync — data will be written before finishing.
  • fsync — data and metadata will be written before finishing.

✨ Input flags ✨

  • count_bytes — a value to count=N will be interpreted as bytes.
  • skip_bytes — a value to skip=N will be interpreted as bytes.
  • fullblock — wait for ibs bytes from each read. zero-length reads are still considered EOF.

🌈 Output flags 🌈

  • append — open file in append mode. consider setting conv=notrunc as well.
  • seek_bytes — a value to seek=N will be interpreted as bytes.

🧚 General flags 🧚

  • direct — use direct I/O for data.
  • directory — fail unless the given input (if used as an iflag) or output (if used as an oflag) is a directory.
  • dsync — use synchronized I/O for data.
  • sync — use synchronized I/O for data and metadata.
  • nonblock — use non-blocking I/O.
  • noatime — do not update access time.
  • nocache — request that OS drop cache.
  • noctty — do not assign a controlling tty.
  • nofollow — do not follow system links.

👑 VERSION 👑

v(uutils coreutils) 0.12.0

🫶 that's the page, bestie — v(uutils coreutils) 0.12.0, dated 2026-09-17. periodt. 💖

📦 where this page comes from