diff options
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/coreutils.texi | 50 |
1 files changed, 40 insertions, 10 deletions
diff --git a/doc/coreutils.texi b/doc/coreutils.texi index 52838e747..02c3a2a5d 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -8057,18 +8057,24 @@ When converting variable-length records to fixed-length ones (@option{conv=block}) or the reverse (@option{conv=unblock}), use @var{bytes} as the fixed record length. -@item skip=@var{blocks} +@item skip=@var{n} @opindex skip -Skip @var{blocks} @samp{ibs}-byte blocks in the input file before copying. +Skip @var{n} @samp{ibs}-byte blocks in the input file before copying. +If @samp{iflag=skip_bytes} is specified, @var{n} is interpreted +as a byte count rather than a block count. -@item seek=@var{blocks} +@item seek=@var{n} @opindex seek -Skip @var{blocks} @samp{obs}-byte blocks in the output file before copying. +Skip @var{n} @samp{obs}-byte blocks in the output file before copying. +if @samp{oflag=seek_bytes} is specified, @var{n} is interpreted +as a byte count rather than a block count. -@item count=@var{blocks} +@item count=@var{n} @opindex count -Copy @var{blocks} @samp{ibs}-byte blocks from the input file, instead +Copy @var{n} @samp{ibs}-byte blocks from the input file, instead of everything until the end of the file. +if @samp{iflag=count_bytes} is specified, @var{n} is interpreted +as a byte count rather than a block count. @item status=noxfer @opindex status @@ -8321,6 +8327,27 @@ When that happens, continue calling @code{read} to fill the remainder of the block. This flag can be used only with @code{iflag}. +@item count_bytes +@opindex count_bytes +Interpret the @samp{count=} operand as a byte count, +rather than a block count, which allows specifying +a length that is not a multiple of the I/O block size. +This flag can be used only with @code{iflag}. + +@item skip_bytes +@opindex skip_bytes +Interpret the @samp{skip=} operand as a byte count, +rather than a block count, which allows specifying +an offset that is not a multiple of the I/O block size. +This flag can be used only with @code{iflag}. + +@item seek_bytes +@opindex seek_bytes +Interpret the @samp{seek=} operand as a byte count, +rather than a block count, which allows specifying +an offset that is not a multiple of the I/O block size. +This flag can be used only with @code{oflag}. + @end table These flags are not supported on all systems, and @samp{dd} rejects @@ -8343,10 +8370,13 @@ should not be too large---values larger than a few megabytes are generally wasteful or (as in the gigabyte..exabyte case) downright counterproductive or error-inducing. -Use different @command{dd} invocations to use different block sizes for -skipping and I/O@. For example, the following shell commands copy data -in 512 KiB blocks between a disk and a tape, but do not save or restore a -4 KiB label at the start of the disk: +To process data that is at an offset or size that is not a +multiple of the I/O@ block size, you can use the @samp{skip_bytes}, +@samp{seek_bytes} and @samp{count_bytes} flags. Alternatively +the traditional method of separate @command{dd} invocations can be used. +For example, the following shell commands copy data +in 512 KiB blocks between a disk and a tape, but do not save +or restore a 4 KiB label at the start of the disk: @example disk=/dev/rdsk/c0t1d0s2 |