Copy a file, converting and formatting according to the operands.
Tag | Description |
bs=BYTES
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force ibs=BYTES and obs=BYTES
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cbs=BYTES
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convert BYTES bytes at a time
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conv=CONVS
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convert the file as per the comma separated symbol list
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count=BLOCKS
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copy only BLOCKS input blocks
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ibs=BYTES
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read BYTES bytes at a time
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if=FILE
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read from FILE instead of stdin
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iflag=FLAGS
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read as per the comma separated symbol list
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obs=BYTES
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write BYTES bytes at a time
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of=FILE
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write to FILE instead of stdout
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oflag=FLAGS
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write as per the comma separated symbol list
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seek=BLOCKS
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skip BLOCKS obs-sized blocks at start of output
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skip=BLOCKS
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skip BLOCKS ibs-sized blocks at start of input
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status=noxfer
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suppress transfer statistics
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BLOCKS and BYTES may be followed by the following multiplicative suffixes:
xM M, c 1, w 2, b 512, kB 1000, K 1024, MB 1000*1000, M 1024*1024,
GB 1000*1000*1000, G 1024*1024*1024, and so on for T, P, E, Z, Y.
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Each CONV symbol may be:
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ascii
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from EBCDIC to ASCII
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ebcdic
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from ASCII to EBCDIC
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ibm
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from ASCII to alternate EBCDIC
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block
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pad newline-terminated records with spaces to cbs-size
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unblock
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replace trailing spaces in cbs-size records with newline
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lcase
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change upper case to lower case
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nocreat
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do not create the output file
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excl
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fail if the output file already exists
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notrunc
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do not truncate the output file
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ucase
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change lower case to upper case
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swab
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swap every pair of input bytes
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noerror
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continue after read errors
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sync
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pad every input block with NULs to ibs-size; when used
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with block or unblock, pad with spaces rather than NULs
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fdatasync physically write output file data before finishing
fsync likewise, but also write metadata
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Each FLAG symbol may be:
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append
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append mode (makes sense only for output)
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direct
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use direct I/O for data
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dsync
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use synchronized I/O for data
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sync
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likewise, but also for metadata
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nonblock
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use non-blocking I/O
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nofollow
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do not follow symlinks
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noctty
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do not assign controlling terminal from file
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Sending a USR1 signal to a running dd process makes it
print I/O statistics to standard error and then resume copying.
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$ dd if=/dev/zero of=/dev/null& pid=$!
$ kill -USR1 $pid; sleep 1; kill $pid
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18335302+0 records in
18335302+0 records out
9387674624 bytes (9.4 GB) copied, 34.6279 seconds, 271 MB/s
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Options are:
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--help
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display this help and exit
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--version
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output version information and exit
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