fix: resolve imports and remove unused ones

src/main.rs

@@ -2,13 +2,10 @@ use nix::fcntl::FdFlag;
 use nix::unistd::{close, pipe};
 use nix::Error as NixError;
 use std::collections::HashMap;
-use std::fs;
 use std::io;
-use std::io::{BufWriter, Read, Write};
 use std::os::fd::FromRawFd;
 use std::path::PathBuf;
 use std::process::Stdio; // For Stdio::null, Stdio::piped
-use std::str::FromStr;
 
 use anyhow::{anyhow, Context, Error, Result};
 use clap::error::ErrorKind;