Differential D21441
Add iflag=fullblock to dd Authored by freqlabs on Aug 27 2019, 6:25 PM. Tags None Referenced Files
Details
Normally, count=n means read(2) will be called n times on the input to dd. If the read() returns short, as may happen when reading from a pipe, fewer bytes will be copied from the input. With conv=sync the buffer is padded with zeros to fill the rest of the block. iflag=fullblock causes dd to continue reading until the block is full, so that count=n means n full blocks are copied. This flag is compatible with illumos and GNU dd and is used in the ZFS test suite. Sponsored by: iXsystems, Inc. # Notice a varying number of partial reads being padded: dd if=/var/log/messages bs=8 | dd bs=64 conv=sync | hexdump | fgrep '*' | wc -l # 634 # 658 # 623 # ... # Notice 0 partial reads: dd if=/var/log/messages bs=8 | dd bs=64 iflag=fullblock | hexdump | fgrep '*' | wc -l # 0 # 0 # 0 # ...
Diff Detail
Event TimelineComment Actions Make conv=sync and iflag=fullblock mutually exclusive rather than silently ignoring the iflag. Comment Actions Can you run textproc/igor and "mandoc -Tlint" over your man page? It should give you some warnings/hints on how to fix a few things in there, nothing major.
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