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https://github.com/uutils/coreutils
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Merge pull request #225 from molysgaard/master
Rudamentary tail implementation.
This commit is contained in:
commit
a55508fba0
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@ -184,7 +184,7 @@ To do
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- stty (in progress)
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- sync
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- tac-pipe
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- tail
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- tail (not all features implemented)
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- test
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- timeout
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- tsort
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17
tail/README.md
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17
tail/README.md
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@ -0,0 +1,17 @@
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Rudamentary tail implementation.
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##Missing features:
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### Flags with features
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* `--bytes` : output the last K bytes; alternatively, use `-c` +K to output bytes starting with the Kth of each file
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* `--max-unchanged-stats` : with `--follow=name`, reopen a FILE which has not changed size after N (default 5) iterations to see if it has been unlinked or renamed (this is the usual case of rotated log files). With inotify, this option is rarely useful.
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* `--pid` : with `-f`, terminate after process ID, PID dies
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* `--quiet` : never output headers giving file names
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* `--retry` : keep trying to open a file even when it is or becomes inaccessible; useful when follow‐ing by name, i.e., with `--follow=name`
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* `--verbose` : always output headers giving file names
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### Others
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The current implementation does not handle `-` as an alias for stdin.
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##Possible optimizations:
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* Don't read the whole file if not using `-f` and input is regular file. Read in chunks from the end going backwards, reading each individual chunk forward.
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185
tail/tail.rs
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185
tail/tail.rs
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@ -0,0 +1,185 @@
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#![crate_id(name="tail", vers="1.0.0", author="Morten Olsen Lysgaard")]
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/*
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* This file is part of the uutils coreutils package.
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*
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* (c) Morten Olsen Lysgaard <morten@lysgaard.no>
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*
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* For the full copyright and license information, please view the LICENSE
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* file that was distributed with this source code.
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*
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*/
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extern crate getopts;
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use std::os;
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use std::char;
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use std::io::{stdin};
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use std::io::BufferedReader;
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use std::io::fs::File;
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use std::path::Path;
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use getopts::{optopt, optflag, getopts, usage};
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use std::collections::Deque;
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use std::collections::ringbuf::RingBuf;
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use std::io::timer::sleep;
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static PROGRAM: &'static str = "tail";
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#[allow(dead_code)]
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fn main () { uumain(os::args()); }
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pub fn uumain(args: Vec<String>) {
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let mut line_count = 10u;
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let mut sleep_sec = 1000u;
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// handle obsolete -number syntax
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let options = match obsolete(args.tail()) {
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(args, Some(n)) => { line_count = n; args },
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(args, None) => args
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};
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let args = options;
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let possible_options = [
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optopt("n", "number", "Number of lines to print", "n"),
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optflag("f", "follow", "Print the file as it grows"),
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optopt("s", "sleep-interval", "Number or seconds to sleep between polling the file when running with -f", "n"),
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optflag("h", "help", "help"),
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optflag("V", "version", "version"),
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];
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let given_options = match getopts(args.as_slice(), possible_options) {
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Ok (m) => { m }
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Err(_) => {
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println!("{:s}", usage(PROGRAM, possible_options));
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return
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}
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};
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if given_options.opt_present("h") {
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println!("{:s}", usage(PROGRAM, possible_options));
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return;
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}
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if given_options.opt_present("V") { version(); return }
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let follow = given_options.opt_present("f");
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if follow {
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match given_options.opt_str("s") {
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Some(n) => {
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let parsed : Option<u64> = from_str(n.as_slice());
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match parsed {
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Some(m) => { sleep_sec = m*1000 }
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None => {}
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}
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}
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None => {}
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};
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}
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match given_options.opt_str("n") {
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Some(n) => {
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match from_str(n.as_slice()) {
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Some(m) => { line_count = m }
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None => {}
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}
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}
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None => {}
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};
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let files = given_options.free;
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if files.is_empty() {
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let mut buffer = BufferedReader::new(stdin());
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tail(&mut buffer, line_count, follow, sleep_sec);
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} else {
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let mut multiple = false;
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let mut firstime = true;
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if files.len() > 1 {
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multiple = true;
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}
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for file in files.iter() {
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if multiple {
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if !firstime { println!(""); }
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println!("==> {:s} <==", file.as_slice());
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}
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firstime = false;
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let path = Path::new(file.as_slice());
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let reader = File::open(&path).unwrap();
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let mut buffer = BufferedReader::new(reader);
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tail(&mut buffer, line_count, follow, sleep_sec);
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}
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}
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}
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// It searches for an option in the form of -123123
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//
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// In case is found, the options vector will get rid of that object so that
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// getopts works correctly.
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fn obsolete (options: &[String]) -> (Vec<String>, Option<uint>) {
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let mut options: Vec<String> = Vec::from_slice(options);
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let mut a = 0;
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let b = options.len();
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while a < b {
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let current = options.get(a).clone();
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let current = current.as_slice();
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if current.len() > 1 && current[0] == '-' as u8 {
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let len = current.len();
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for pos in range(1, len) {
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// Ensure that the argument is only made out of digits
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if !char::is_digit(current.char_at(pos)) { break; }
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// If this is the last number
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if pos == len - 1 {
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options.remove(a);
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let number : Option<uint> = from_str(current.slice(1,len));
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return (options, Some(number.unwrap()));
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}
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}
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}
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a += 1;
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};
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(options, None)
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}
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fn tail<T: Reader> (reader: &mut BufferedReader<T>, line_count:uint, follow:bool, sleep_sec:u64) {
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// read trough each line and store them in a ringbuffer that always contains
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// line_count lines. When reaching the end of file, output the lines in the
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// ringbuf.
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let mut ringbuf : RingBuf<String> = RingBuf::new();
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for io_line in reader.lines(){
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match io_line {
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Ok(line) => {
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if line_count<=ringbuf.len(){
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ringbuf.pop_front();
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}
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ringbuf.push_back(line);
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}
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Err(err) => fail!(err)
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}
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}
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for line in ringbuf.iter() {
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print!("{}", line);
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}
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// if we follow the file, sleep a bit and print the rest if the file has grown.
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while follow {
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sleep(sleep_sec);
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for io_line in reader.lines() {
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match io_line {
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Ok(line) => print!("{}", line),
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Err(err) => fail!(err)
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}
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}
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}
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}
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fn version () {
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println!("tail version 0.0.1");
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}
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