If `conv=block,sync` command-line arguments are given and there is at
least one partial record read from the input (for example, if the
length of the input is not divisible by the value of the `ibs`
argument), then output an extra block of `cbs` spaces.
For example, no extra spaces are printed in this example because the
input is of length 10, a multiple of `ibs`:
$ printf "012\nabcde\n" \
> | dd ibs=5 cbs=5 conv=block,sync status=noxfer \
> && echo $
012 abcde$
2+0 records in
0+1 records out
But in this example, 5 extra spaces are printed because the length of
the input is not a multiple of `ibs`:
$ printf "012\nabcdefg\n" \
> | dd ibs=5 cbs=5 conv=block,sync status=noxfer \
> && echo $
012 abcde $
2+1 records in
0+1 records out
1 truncated record
The number of spaces printed is the size of the conversion block,
given by `cbs`.
This should correct the usage strings in both the `--help` and user documentation. Previously, sometimes the name of the utils did not show up correctly.
Create a new module `blocks.rs` to contain the block-related helper
functions. This commit only moves the location of the code and related
tests, it does not change the functionality of `dd`.
Collect structs, implementations, and functions that have to do with
reporting number of blocks read and written into their own new module,
`progress.rs`. This commit also adds docstrings for everything and
unit tests for the significant methods. This commit does not change
the behavior of `dd`, just the organization of the code to make it
more maintainable and testable.
Prevent `dd` from terminating with an error when given the
command-line argument `of=/dev/null`. This commit allows the call to
`File::set_len()` to result in an error without causing the process to
terminate prematurely.
- Configured clap to take crate version, so version is now visible in docs.
- Added ABOUT string from expr help output, so about section is getting rendered in docs.
- Added USAGE section.
- Added HELP section for each args.
Place the "truncated records" line below the "records out" line in the
status report produced by `dd` and properly handle the singularization
of the word "record" in the case of 1 truncated record. This matches
the behavior of GNU `dd`.
For example
$ printf "ab" | dd cbs=1 conv=block status=noxfer > /dev/null
0+1 records in
0+1 records out
1 truncated record
$ printf "ab\ncd\n" | dd cbs=1 conv=block status=noxfer > /dev/null
0+1 records in
0+1 records out
2 truncated records
Add the `-e` flag, which indicates whether to elide (that is, remove)
empty files that would have been created by the `-n` option.
The `-n` command-line argument gives a specific number of chunks into
which the input files will be split. If the number of chunks is
greater than the number of bytes, then empty files will be created for
the excess chunks. But if `-e` is given, then empty files will not be
created.
For example, contrast
$ printf 'a\n' > f && split -e -n 3 f && cat xaa xab xac
a
cat: xac: No such file or directory
with
$ printf 'a\n' > f && split -n 3 f && cat xaa xab xac
a
