Expand description
dd(1)
: dd if=/dev/zero of=/dev/null bs=1000
//! This is not a typical bpaf usage, but you should be able to replicate command line used by dd
use bpaf::*;
use std::str::FromStr;
#[derive(Debug, Clone)]
#[allow(dead_code)]
pub struct Options {
magic: bool,
in_file: String,
out_file: String,
block_size: usize,
}
fn tag<T>(name: &'static str, meta: &'static str, help: &'static str) -> impl Parser<T>
where
T: FromStr,
<T as std::str::FromStr>::Err: std::fmt::Display,
{
// it is possible to parse OsString here and strip the prefix with os_str_bytes or a similar
// crate
any::<String>(meta)
.help(help)
.parse::<_, _, String>(move |s| match s.strip_prefix(name) {
None => Err("Wrong tag".to_string()),
Some(body) => T::from_str(body).map_err(|e| e.to_string()),
})
.anywhere()
}
fn in_file() -> impl Parser<String> {
tag::<String>("if=", "if=FILE", "read from FILE instead of stdin").fallback(String::from("-"))
}
fn out_file() -> impl Parser<String> {
tag::<String>("of=", "of=FILE", "write to FILE instead of stdout").fallback(String::from("-"))
}
fn block_size() -> impl Parser<usize> {
// it is possible to parse notation used by dd itself as well, using only ints for simplicity
tag::<usize>(
"bs=",
"bs=SIZE",
"read/write SIZE blocks at once instead of 512",
)
.fallback(512)
}
pub fn options() -> OptionParser<Options> {
let magic = long("magic").switch();
construct!(Options {
magic,
in_file(),
out_file(),
block_size(),
})
.to_options()
}
fn main() {
println!("{:#?}", options().run());
}
Examples
dd
takes parameters in name=value
shape
% app if=/dev/zero of=file bs=10000
Options { magic: false, in_file: "/dev/zero", out_file: "file", block_size: 10000 }
Usual properties about ordering holds, you can also mix them with regular options
% app if=/dev/zero of=file bs=10000 --magic
Options { magic: true, in_file: "/dev/zero", out_file: "file", block_size: 10000 }
Fallback works as expected
% app --magic bs=42
Options { magic: true, in_file: "-", out_file: "-", block_size: 42 }
Best effort to generate help, but you can always customize it further
% app --help
Usage: [--magic] [<if=FILE>] [<of=FILE>] [<bs=SIZE>]
Available positional items:
<if=FILE> read from FILE instead of stdin
<of=FILE> write to FILE instead of stdout
<bs=SIZE> read/write SIZE blocks at once instead of 512
Available options:
--magic
-h, --help Prints help information