Since sort exits early due to the nonexistent file, it might no longer
be around when we try to send it the input.
This is "by design" and can be ignored.
In such cases we have to create a temporary copy of the input file to prevent
overwriting the input with the output. This only affects merge sort, because it
is the only mode where we start writing to the output before having read all inputs.
Since lines that compare equal should be sorted together, we need to first
compare the lines (taking settings into account). Only if they do not compare
equal we should compare the hashes.
Use new macro to construct UIoError types from `std::io::Error` before
printing. This gives consistent error messages across all utilities as it
prepends custom errors to the error description for the respective application
and error type. This saves the developers from manually appending the
`std::io::Error`-specific error messages.
Adds a new macro `uio_error` that acts as a convenience wrapper for
constructing `UIoError` instances from `std::io::Error`s with a custom error
message prepended. It constructs a new `UIoError` instance for the user.
Usage examples are included in the docs.
Drop the previous flags that would tell whether a noncritical error occured
during execution in favor of the `show!` macro from the error submodule.
This allows us to generate regular error types during execution to signify
failures inside the program, but without prematurely aborting program execution
if not needed or specified.
Also make verbose outputs use `print!` and friends instead of `show_error!` to
ensure verbose output is redirected to stdout, not stderr.
Add support for
* space-separated list of tab stops, like `--tabs="2 4 6"`,
* mixed comma- and space-separated lists, like `--tabs="2,4 6"`,
* the slash specifier in the last tab stop, like `--tabs=1,/5`,
* the plus specifier in the last tab stop, like `--tabs=1,+5`.
The custom usage string does not have to include the "sort\nUsage:" part,
because this part is already printed by clap.
It prevents the following duplication:
USAGE:
sort
Usage:
sort [OPTION]... [FILE]..
Now, only the following is printed:
USAGE:
sort [OPTION]... [FILE]...
