Convert a file while copying it (UNIX)
dd [if=input_file] [of=output_file] [options]
Neutrino
- bs=bytes
- Read and write bytes bytes at a time.
This option overrides ibs and obs.
- cbs=bytes
- Convert bytes bytes at a time.
- conv=conversion[,conversion...]
- Convert the file as specified by the conversion arguments.
Conversions are:
- ascii
- Convert EBCDIC to ASCII.
- block
- Pad newline-terminated records to the size specified by
cbs, replacing the newline with trailing spaces.
- ebcdic
- Convert ASCII to EBCDIC.
- ibm
- Convert ASCII to alternate EBCDIC.
- lcase
- Change uppercase characters to lowercase.
- noerror
- Continue after read errors.
- notrunc
- Don't truncate the output file.
- swab
- Swap every pair of input bytes.
Unlike the UNIX dd, this works when an odd number of bytes
are read.
If the input file contains an odd number of bytes, the last byte is
simply copied (since there's nothing to swap it with).
- sync
- Pad every input block with trailing NULs, to the size of
ibs.
- ucase
- Change lowercase characters to uppercase.
- unblock
- Remove any trailing spaces in each cbs-sized block,
and add a newline.
- count=blocks
- Copy only blocks ibs-sized input blocks.
The default is no limit.
- ibs=bytes
- Read bytes bytes at a time.
The default is 512 bytes.
- if=input_file
- Read from input_file instead of the standard input.
- obs=bytes
- Write bytes bytes at a time.
The default is 512 bytes.
- of=output_file
- Write to output_file instead of the standard output. Unless
conv=notrunc is given, truncate the file to the size
specified by seek (or 0 bytes if seek
isn't given).
- seek=blocks
- Skip blocks obs-sized blocks at the start of output.
- skip=blocks
- Skip blocks ibs-sized blocks at the start of input.
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You can follow all numbers by a multiplier:
- b
- Blocks (×512).
- k
- Kbytes (×1024).
- w
- Words (×2).
- xm
- Multiply by m.
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The dd
utility copies a file (from the standard input to the standard output, by default)
with a user-selectable blocksize, while optionally performing conversions
on it. It's meant for writing raw data directly to devices such as
tape and disk or writing over the network, with control over blocking
factors and character set translations.
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This utility is subject to the GNU Public License (GPL).
We've included it for use on development systems. |
You can use this command for copying partial files.
You can specify the block size, skip count, and the number of blocks to copy.
Sizes are in bytes by default;
you can append the letters w, b, or k to the
number to indicate words (2 bytes), blocks (512 bytes), or K (1024 bytes).
When dd is finished, it reports the number of full and
partial blocks read and written.
Copy file file1 to file2, converting
all text to lowercase letters:
dd if=file1 of=file2 conv=lcase
- >0
- An error occurred.
- 0
- The copy and translation operation was successful.
GNU
cat,
cp,
pax,
head,
tr