{
"mode": "man",
"parameter": "dd",
"section": "1",
"url": "https://www.chedong.com/phpMan.php/man/dd/1/json",
"generated": "2026-06-03T00:25:16Z",
"synopsis": "dd [OPERAND]...\ndd OPTION",
"sections": {
"NAME": {
"content": "dd - convert and copy a file\n",
"subsections": []
},
"SYNOPSIS": {
"content": "dd [OPERAND]...\ndd OPTION\n",
"subsections": []
},
"DESCRIPTION": {
"content": "Copy a file, converting and formatting according to the operands.\n\nbs=BYTES\nread and write up to BYTES bytes at a time (default: 512); overrides ibs and obs\n\ncbs=BYTES\nconvert BYTES bytes at a time\n\nconv=CONVS\nconvert the file as per the comma separated symbol list\n\ncount=N\ncopy only N input blocks\n\nibs=BYTES\nread up to BYTES bytes at a time (default: 512)\n\nif=FILE\nread from FILE instead of stdin\n\niflag=FLAGS\nread as per the comma separated symbol list\n\nobs=BYTES\nwrite BYTES bytes at a time (default: 512)\n\nof=FILE\nwrite to FILE instead of stdout\n\noflag=FLAGS\nwrite as per the comma separated symbol list\n\nseek=N skip N obs-sized blocks at start of output\n\nskip=N skip N ibs-sized blocks at start of input\n\nstatus=LEVEL\nThe LEVEL of information to print to stderr; 'none' suppresses everything but error\nmessages, 'noxfer' suppresses the final transfer statistics, 'progress' shows periodic\ntransfer statistics\n\nN and BYTES may be followed by the following multiplicative suffixes: c=1, w=2, b=512,\nkB=1000, K=1024, MB=1000*1000, M=1024*1024, xM=M, GB=1000*1000*1000, G=1024*1024*1024, and so\non for T, P, E, Z, Y. Binary prefixes can be used, too: KiB=K, MiB=M, and so on.\n\nEach CONV symbol may be:\n\nascii from EBCDIC to ASCII\n\nebcdic from ASCII to EBCDIC\n\nibm from ASCII to alternate EBCDIC\n\nblock pad newline-terminated records with spaces to cbs-size\n\nunblock\nreplace trailing spaces in cbs-size records with newline\n\nlcase change upper case to lower case\n\nucase change lower case to upper case\n\nsparse try to seek rather than write all-NUL output blocks\n\nswab swap every pair of input bytes\n\nsync pad every input block with NULs to ibs-size; when used with block or unblock, pad with\nspaces rather than NULs\n\nexcl fail if the output file already exists\n\nnocreat\ndo not create the output file\n\nnotrunc\ndo not truncate the output file\n\nnoerror\ncontinue after read errors\n\nfdatasync\nphysically write output file data before finishing\n\nfsync likewise, but also write metadata\n\nEach FLAG symbol may be:\n\nappend append mode (makes sense only for output; conv=notrunc suggested)\n\ndirect use direct I/O for data\n\ndirectory\nfail unless a directory\n\ndsync use synchronized I/O for data\n\nsync likewise, but also for metadata\n\nfullblock\naccumulate full blocks of input (iflag only)\n\nnonblock\nuse non-blocking I/O\n\nnoatime\ndo not update access time\n\nnocache\nRequest to drop cache. See also oflag=sync\n\nnoctty do not assign controlling terminal from file\n\nnofollow\ndo not follow symlinks\n\ncountbytes\ntreat 'count=N' as a byte count (iflag only)\n\nskipbytes\ntreat 'skip=N' as a byte count (iflag only)\n\nseekbytes\ntreat 'seek=N' as a byte count (oflag only)\n\nSending a USR1 signal to a running 'dd' process makes it print I/O statistics to standard er‐\nror and then resume copying.\n\nOptions are:\n\n--help display this help and exit\n",
"subsections": [
{
"name": "--version",
"content": "output version information and exit\n",
"long": "--version"
}
]
},
"AUTHOR": {
"content": "Written by Paul Rubin, David MacKenzie, and Stuart Kemp.\n",
"subsections": []
},
"REPORTING BUGS": {
"content": "GNU coreutils online help: \nReport any translation bugs to \n",
"subsections": []
},
"COPYRIGHT": {
"content": "Copyright © 2020 Free Software Foundation, Inc. License GPLv3+: GNU GPL version 3 or later\n.\nThis is free software: you are free to change and redistribute it. There is NO WARRANTY, to\nthe extent permitted by law.\n",
"subsections": []
},
"SEE ALSO": {
"content": "Full documentation \nor available locally via: info '(coreutils) dd invocation'\n\n\n\nGNU coreutils 8.32 January 2026 DD(1)",
"subsections": []
}
},
"summary": "dd - convert and copy a file",
"flags": [
{
"flag": "",
"long": "--version",
"arg": null,
"description": "output version information and exit"
}
],
"examples": [],
"see_also": [],
"tldr": {
"source": "official",
"description": "Convert and copy a file.",
"examples": [
{
"description": "Make a bootable USB drive from an isohybrid file (such as `archlinux-xxx.iso`) and show the progress",
"command": "dd if={{path/to/file.iso}} of={{/dev/usb_drive}} status=progress"
},
{
"description": "Clone a drive to another drive with 4 MiB block size and flush writes before the command terminates",
"command": "dd bs=4194304 conv=fsync if={{/dev/source_drive}} of={{/dev/dest_drive}}"
},
{
"description": "Generate a file with a specific number of random bytes by using kernel random driver",
"command": "dd bs={{100}} count={{1}} if=/dev/urandom of={{path/to/random_file}}"
},
{
"description": "Benchmark the sequential write performance of a disk",
"command": "dd bs={{1024}} count={{1000000}} if=/dev/zero of={{path/to/file_1GB}}"
},
{
"description": "Create a system backup, save it into an IMG file (can be restored later by swapping `if` and `of`), and show the progress",
"command": "dd if={{/dev/drive_device}} of={{path/to/file.img}} status=progress"
}
]
}
}