dd(1)

💖 NAME 💖

okay so bestie, meet dd — the manual is called dd(1) and it's a General Commands Manual entry, and what it does is literally this: Copy, and optionally convert, a file system resource. that's it, that's the whole vibe. copy stuff, maybe transform it on the way, iconic behavior honestly 🦋

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✨ SYNOPSIS ✨

dd [-h|--help] [-V|--version] [operands]

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🌸 DESCRIPTION 🌸

Copy, and optionally convert, a file system resource

like. that's the whole job description and she does it FLAWLESSLY. 💅

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👑 OPTIONS 👑

• -h, --help — Print help. she will tell you how to use her, no gatekeeping 💜
• -V, --version — Print version. she will tell you who she is 🎀
• [operands] — yes bestie, the operands go here (see the EXTRA section below, they're the main character fr fr)

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🌈 EXTRA 🌈

🌟 Operands 🌟

these are the real ones, the whole personality, no cap:

• bs=BYTES — read and write up to BYTES bytes at a time (default: 512); overwrites ibs and obs. she's the boss of both of them, periodt.
• 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.
• 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.

bestie listen. that POSIXLY_CORRECT thing is real — set it to literally anything, even nothing at all, and USR1 gets ignored. don't come crying to me 😭

🧚 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 : converts 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 in 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.

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⭐ VERSION ⭐

v(uutils coreutils) 0.7.0

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and that's the whole page bestie!! this is dd (uutils coreutils) 0.7.0 — that's the source and the version right there, so if anyone asks, you know exactly which build of uutils coreutils you're out here slaying with 💅✨ go copy something and make it cute, mwah 🫶