diff --git a/README.md b/README.md
index d48f63a..d634b7d 100644
--- a/README.md
+++ b/README.md
@@ -1,6 +1,7 @@
 # LF Fixer
 
-View the LF stats of files in your repository.
+- View the line ending stats.
+- Normalize line endings.
 
 ## Installation
 
@@ -16,7 +17,7 @@ lf_fixer --help
 
 ## TODO
 
-- Edit files to fix line ending mismatches
-    - To user defined line ending,
-    - To the line ending of the majority of the files
-- Add tests
+- [x] Edit files to fix line ending mismatches
+    - [x] To user defined line ending,
+    - [x] To the line ending of the majority of the files
+- [] Add tests
diff --git a/src/fixer.rs b/src/fixer.rs
index 13774aa..14564a2 100644
--- a/src/fixer.rs
+++ b/src/fixer.rs
@@ -22,16 +22,16 @@ impl Fixer {
     }
 
     pub(crate) fn fix(&mut self) {
-        let file = File::options().read(true).write(true).open(&self.file_name);
+        let file = File::options().read(true).open(&self.file_name);
         if file.is_err() {
             println!("Could not open file: {}", self.file_name);
             return;
         }
 
         let mut file = file.unwrap();
-        let mut buf = Vec::new();
-        let mut write_buf = Vec::new();
-        let bytes_read = file.read_to_end(&mut buf);
+        let mut read_buf = Vec::with_capacity(1024 * 1024);
+        let mut write_buf = Vec::with_capacity(1024 * 1024);
+        let bytes_read = file.read_to_end(&mut read_buf);
 
         if bytes_read.is_err() {
             println!("Could not read file: {}", self.file_name);
@@ -39,44 +39,66 @@ impl Fixer {
         }
 
         let bytes_read = bytes_read.unwrap();
-        let mut next_read_head = 0;
+        let mut read_head: usize = 0;
+        let mut write_head: usize = 0;
 
         loop {
-            if next_read_head == bytes_read {
+            if read_head == bytes_read {
                 break;
             }
 
-            next_read_head = match buf[next_read_head] {
+            let byte = read_buf[read_head];
+            read_head = match byte {
                 b'\r' => {
+                    self.normalize_ending(&mut write_buf, &mut write_head);
+                    let lf_index = read_head + 1;
                     // LL(1) to see if the next byte is '\n'
-                    if next_read_head < bytes_read && buf[next_read_head] == b'\n' {
-                        write_buf.extend(&self.to);
-                        next_read_head + 2
+                    if lf_index < bytes_read && read_buf[lf_index] == b'\n' {
+                        lf_index + 1
                     } else {
-                        next_read_head + 1
+                        read_head + 1
                     }
                 }
                 b'\n' => {
-                    write_buf.extend(&self.to);
-                    next_read_head + 1
+                    self.normalize_ending(&mut write_buf, &mut write_head);
+                    read_head + 1
                 }
-                any_other_byte => {
-                    write_buf.push(any_other_byte);
-                    next_read_head + 1
+                _ => {
+                    write_buf.push(byte);
+                    write_head = write_head + 1;
+                    read_head + 1
                 }
             }
         }
 
-        let seeked = file.seek(SeekFrom::Start(0));
-        if seeked.is_err() {
-            println!("Could not seek to start of file: {}", self.file_name);
+        drop(file);
+
+        let file = File::options()
+            .write(true)
+            .truncate(true)
+            .open(&self.file_name);
+        if file.is_err() {
+            println!("Could not open file: {}", self.file_name);
+            return;
+        }
+        let mut file = file.unwrap();
+        let written = file.write_all(&write_buf[0..write_head]);
+        if written.is_err() {
+            println!(
+                "Could not write to file: {} {:?}",
+                self.file_name,
+                written.err()
+            );
             return;
         }
 
-        let written = file.write_all(&write_buf);
-        if written.is_err() {
-            println!("Could not write to file: {}", self.file_name);
-            println!("Error: {:?}", written.err());
+        println!("Fixed line endings in file: {}", self.file_name);
+    }
+
+    fn normalize_ending(&self, write_buf: &mut Vec<u8>, write_head: &mut usize) {
+        for &b in &self.to {
+            write_buf.push(b);
+            *write_head += 1;
         }
     }
 }
diff --git a/src/iter.rs b/src/iter.rs
new file mode 100644
index 0000000..24d629a
--- /dev/null
+++ b/src/iter.rs
@@ -0,0 +1,146 @@
+use std::fs::{self, ReadDir};
+
+use crate::{filters::FileFilter, Args};
+
+pub(crate) struct SingleFileName {
+    file_name: Option<String>,
+}
+
+pub(crate) struct MultipleFileNames {
+    cur_dir: Option<String>,
+    filter: FileFilter,
+    all_dirs: Vec<String>,
+    cur_dir_files: Vec<String>,
+    recursive: bool,
+}
+
+pub(crate) enum FileNames {
+    Single(SingleFileName),
+    Multiple(MultipleFileNames),
+}
+
+impl SingleFileName {
+    fn new(file_name: String) -> SingleFileName {
+        SingleFileName {
+            file_name: Some(file_name),
+        }
+    }
+}
+
+impl MultipleFileNames {
+    fn get_next_dir(&mut self) -> Option<ReadDir> {
+        loop {
+            if let Some(dir) = self.all_dirs.pop() {
+                let entries = fs::read_dir(&dir);
+                if entries.is_err() {
+                    println!("Could not read dir: {}", dir);
+                    continue;
+                }
+
+                return Some(entries.unwrap());
+            }
+
+            return None;
+        }
+    }
+
+    fn populate_files(&mut self) -> bool {
+        if self.cur_dir_files.len() > 0 {
+            return true;
+        }
+
+        let next_dir = self.get_next_dir();
+        if next_dir.is_none() {
+            return false;
+        }
+
+        let next_dir = next_dir.unwrap();
+        for entry in next_dir {
+            if entry.is_err() {
+                println!(
+                    "Could not read file {}, skipping",
+                    entry.unwrap().path().display()
+                );
+                continue;
+            }
+
+            let entry = entry.unwrap();
+            let path = entry.path();
+            if path.is_dir() {
+                if self.recursive {
+                    self.all_dirs.push(path.to_str().unwrap().to_string());
+                }
+            } else if path.is_file() {
+                if self.filter.apply(path.to_str().unwrap()) {
+                    self.cur_dir_files.push(path.to_str().unwrap().to_string());
+                }
+            } else {
+                println!("Skipping {}, unknown file type", path.display());
+            }
+        }
+
+        true
+    }
+}
+
+impl Iterator for MultipleFileNames {
+    type Item = String;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        if let Some(dir) = self.cur_dir.take() {
+            self.all_dirs.push(dir);
+        }
+
+        if let Some(file) = self.cur_dir_files.pop() {
+            return Some(file);
+        }
+
+        loop {
+            let populated = self.populate_files();
+            if !populated {
+                return None;
+            }
+
+            if self.cur_dir_files.len() > 0 {
+                return Some(self.cur_dir_files.pop().unwrap());
+            }
+        }
+    }
+}
+
+impl FileNames {
+    pub(crate) fn new(args: &Args) -> FileNames {
+        if let Some(file_name) = &args.file_name {
+            return FileNames::Single(SingleFileName::new(file_name.to_string()));
+        }
+
+        let cur_dir = match &args.dir {
+            Some(dir) => dir.to_string(),
+            None => "./".to_string(),
+        };
+
+        let filter = match &args.ext {
+            Some(ext) => FileFilter::extension(&ext),
+            None => FileFilter::None,
+        };
+
+        FileNames::Multiple(MultipleFileNames {
+            cur_dir: Some(cur_dir),
+            filter,
+            all_dirs: Vec::new(),
+            cur_dir_files: Vec::new(),
+            recursive: args.recursive,
+        })
+    }
+}
+
+impl Iterator for FileNames {
+    type Item = String;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        match self {
+            FileNames::Single(file_name) => file_name.file_name.take(),
+            FileNames::Multiple(file_names) => file_names.next(),
+        }
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index 375a111..72d1e98 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,54 +1,23 @@
 use argh::FromArgs;
-use filters::FileFilter;
 use fixer::Fixer;
-use stats::{FileNames, FileStats, FileStatsAggregate, LineSep};
+use iter::FileNames;
+use stats::{FileStats, FileStatsAggregate, LineSep};
 mod filters;
 mod fixer;
+mod iter;
 mod stats;
 
-fn main() {
-    let args: Args = argh::from_env();
-
-    let filter = match args.ext {
-        Some(ext) => FileFilter::extension(&ext),
-        None => FileFilter::None,
-    };
-
-    let stats = FileNames::generate(args.dir.clone(), filter.clone(), args.recursive)
-        .filter_map(FileStats::generate)
-        .fold(FileStatsAggregate::new(), FileStatsAggregate::fold);
-    stats.print_table();
-
-    if args.fix {
-        let target = match args.target {
-            Some(target) => {
-                println!("Fixing line endings to provided line ending - {:}", target);
-                target
-            }
-            None => match stats.max() {
-                Some(max) => {
-                    println!("Fixing line endings to most common line ending - {:}", max);
-                    max
-                }
-                None => {
-                    panic!("No line endings found to fix");
-                }
-            },
-        };
-
-        FileNames::generate(args.dir, filter, args.recursive)
-            .map(|file_name| Fixer::new(file_name, target.clone()))
-            .for_each(|mut fixer| fixer.fix());
-    }
-}
-
 /// Line endings fixer tool
 #[derive(FromArgs)]
 struct Args {
     /// directory to search for files in
-    #[argh(positional)]
+    #[argh(option, short = 'd')]
     dir: Option<String>,
 
+    /// specific file to evaluate. All other options are ignored
+    #[argh(positional)]
+    file_name: Option<String>,
+
     /// extension to filter files by : Ex: -e .txt
     #[argh(option, short = 'e')]
     ext: Option<String>,
@@ -57,20 +26,60 @@ struct Args {
     #[argh(switch, short = 'r')]
     recursive: bool,
 
-    /// fix line endings
-    #[argh(switch, short = 'f')]
-    fix: bool,
-
-    /// target line ending, applicable only with -f
-    #[argh(option, short = 't', from_str_fn(parse_line_sep))]
-    target: Option<LineSep>,
+    /// normalize line endings
+    #[argh(option, short = 'n', from_str_fn(parse_norm_option))]
+    normalize: Option<NormalizeOption>,
 }
 
-fn parse_line_sep(s: &str) -> Result<LineSep, String> {
+enum NormalizeOption {
+    /// normalize to the most frequent line ending
+    /// across all files matching the filter.
+    MostFrequent,
+
+    /// normalize to lf
+    Lf,
+
+    /// normalize to crlf
+    CrLf,
+
+    /// normalize to cr
+    Cr,
+}
+
+fn main() {
+    let args: Args = argh::from_env();
+
+    let stats = FileNames::new(&args)
+        .filter_map(FileStats::generate)
+        .fold(FileStatsAggregate::new(), FileStatsAggregate::fold);
+    stats.print_table();
+
+    if let Some(normalize_option) = &args.normalize {
+        let target = match normalize_option {
+            NormalizeOption::Lf => LineSep::Lf,
+            NormalizeOption::CrLf => LineSep::CrLf,
+            NormalizeOption::Cr => LineSep::Cr,
+            NormalizeOption::MostFrequent => match stats.max() {
+                Some(max) => max,
+                None => {
+                    println!("Target line ending could not be determined. Skipping normalization");
+                    return;
+                }
+            },
+        };
+
+        FileNames::new(&args)
+            .map(|file_name| Fixer::new(file_name, target.clone()))
+            .for_each(|mut fixer| fixer.fix());
+    }
+}
+
+fn parse_norm_option(s: &str) -> Result<NormalizeOption, String> {
     match s {
-        "lf" => Ok(LineSep::Lf),
-        "crlf" => Ok(LineSep::CrLf),
-        "cr" => Ok(LineSep::Cr),
+        "lf" => Ok(NormalizeOption::Lf),
+        "crlf" => Ok(NormalizeOption::CrLf),
+        "cr" => Ok(NormalizeOption::Cr),
+        "any" => Ok(NormalizeOption::MostFrequent),
         _ => Err("Invalid line ending".to_string()),
     }
 }
diff --git a/src/stats.rs b/src/stats.rs
index 8c61d62..8ea55a0 100644
--- a/src/stats.rs
+++ b/src/stats.rs
@@ -1,8 +1,15 @@
 use std::fmt::Display;
-use std::fs::{self, File, ReadDir};
+use std::fs::File;
 use std::io::Read;
 
-use crate::filters::FileFilter;
+pub(crate) struct FileStats {
+    name: String,
+    lines: usize,
+    crlf: usize,
+    cr: usize,
+    lf: usize,
+    max: Option<LineSep>,
+}
 
 pub(crate) struct FileStatsAggregate {
     stats: Vec<FileStats>,
@@ -13,6 +20,91 @@ pub(crate) struct FileStatsAggregate {
     lines: usize,
 }
 
+#[derive(Clone)]
+pub(crate) enum LineSep {
+    Lf,
+    CrLf,
+    Cr,
+}
+
+impl FileStats {
+    fn new(name: &str) -> FileStats {
+        FileStats {
+            name: name.to_string(),
+            lines: 0,
+            crlf: 0,
+            cr: 0,
+            lf: 0,
+            max: None,
+        }
+    }
+
+    pub(crate) fn generate(file_name: String) -> Option<FileStats> {
+        let file = File::open(&file_name);
+        if file.is_err() {
+            println!("Could not open file: {}", file_name);
+            return None;
+        }
+        let mut file = file.unwrap();
+        let mut buf = Vec::with_capacity(1024 * 1024);
+
+        let bytes_read = file.read_to_end(&mut buf);
+        if bytes_read.is_err() {
+            println!("Could not read file: {}", file_name);
+            return None;
+        }
+
+        let bytes_read = bytes_read.unwrap();
+
+        let mut stats = FileStats::new(&file_name);
+        let mut i = 0;
+        loop {
+            if i == bytes_read {
+                break Some(stats);
+            }
+
+            let byte = buf[i];
+            if byte == b'\r' {
+                if i + 1 < bytes_read && buf[i + 1] == b'\n' {
+                    stats.update(LineSep::CrLf);
+                    i = i + 1;
+                } else {
+                    stats.update(LineSep::Cr);
+                }
+            } else if byte == b'\n' {
+                stats.update(LineSep::Lf);
+            }
+
+            i = i + 1;
+        }
+    }
+
+    fn update(&mut self, line: LineSep) {
+        self.lines += 1;
+        match line {
+            LineSep::CrLf => {
+                self.crlf += 1;
+            }
+            LineSep::Cr => {
+                self.cr += 1;
+            }
+            LineSep::Lf => {
+                self.lf += 1;
+            }
+        }
+
+        if (self.crlf > self.lf) && (self.crlf > self.cr) {
+            self.max = Some(LineSep::CrLf);
+        } else if (self.lf > self.cr) && (self.lf > self.crlf) {
+            self.max = Some(LineSep::Lf);
+        } else if (self.cr > self.lf) && (self.cr > self.crlf) {
+            self.max = Some(LineSep::Cr);
+        } else {
+            self.max = None;
+        }
+    }
+}
+
 impl FileStatsAggregate {
     pub(crate) fn new() -> Self {
         FileStatsAggregate {
@@ -82,99 +174,6 @@ impl FileStatsAggregate {
     }
 }
 
-pub(crate) struct FileStats {
-    name: String,
-    lines: usize,
-    crlf: usize,
-    cr: usize,
-    lf: usize,
-    max: Option<LineSep>,
-}
-
-impl FileStats {
-    fn new(name: &str) -> FileStats {
-        FileStats {
-            name: name.to_string(),
-            lines: 0,
-            crlf: 0,
-            cr: 0,
-            lf: 0,
-            max: None,
-        }
-    }
-
-    pub(crate) fn generate(file_name: String) -> Option<FileStats> {
-        let file = File::open(&file_name);
-        if file.is_err() {
-            println!("Could not open file: {}", file_name);
-            return None;
-        }
-        let mut file = file.unwrap();
-
-        let mut buf = Vec::new();
-
-        let bytes_read = file.read_to_end(&mut buf);
-        if bytes_read.is_err() {
-            println!("Could not read file: {}", file_name);
-            return None;
-        }
-
-        let bytes_read = bytes_read.unwrap();
-
-        let mut stats = FileStats::new(&file_name);
-        let mut i = 0;
-        loop {
-            if i == bytes_read {
-                break Some(stats);
-            }
-
-            let byte = buf[i];
-            if byte == b'\r' {
-                if i + 1 < bytes_read && buf[i + 1] == b'\n' {
-                    stats.update(LineSep::CrLf);
-                    i = i + 1;
-                } else {
-                    stats.update(LineSep::Cr);
-                }
-            } else if byte == b'\n' {
-                stats.update(LineSep::Lf);
-            }
-
-            i = i + 1;
-        }
-    }
-
-    fn update(&mut self, line: LineSep) {
-        self.lines += 1;
-        match line {
-            LineSep::CrLf => {
-                self.crlf += 1;
-            }
-            LineSep::Cr => {
-                self.cr += 1;
-            }
-            LineSep::Lf => {
-                self.lf += 1;
-            }
-        }
-
-        if (self.crlf > self.lf) && (self.crlf > self.cr) {
-            self.max = Some(LineSep::CrLf);
-        } else if (self.lf > self.cr) && (self.lf > self.crlf) {
-            self.max = Some(LineSep::Lf);
-        } else {
-            self.max = Some(LineSep::Cr);
-        }
-    }
-}
-
-#[derive(Clone)]
-pub(crate) enum LineSep {
-    Lf,
-    CrLf,
-    Cr,
-}
-
 impl Display for LineSep {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         match self {
@@ -184,107 +183,3 @@ impl Display for LineSep {
         }
     }
 }
-
-pub(crate) struct FileNames {
-    cur_dir: Option<String>,
-    filter: FileFilter,
-    all_dirs: Vec<String>,
-    cur_dir_files: Vec<String>,
-    recursive: bool,
-}
-
-impl FileNames {
-    pub(crate) fn generate(dir: Option<String>, pattern: FileFilter, recursive: bool) -> FileNames {
-        let cur_dir = match dir {
-            Some(dir) => dir,
-            None => "./".to_string(),
-        };
-
-        FileNames {
-            cur_dir: Some(cur_dir),
-            filter: pattern,
-            all_dirs: Vec::new(),
-            cur_dir_files: Vec::new(),
-            recursive,
-        }
-    }
-
-    fn get_next_dir(&mut self) -> Option<ReadDir> {
-        loop {
-            if let Some(dir) = self.all_dirs.pop() {
-                let entries = fs::read_dir(&dir);
-                if entries.is_err() {
-                    println!("Could not read dir: {}", dir);
-                    continue;
-                }
-
-                return Some(entries.unwrap());
-            }
-
-            return None;
-        }
-    }
-
-    fn populate_files(&mut self) -> bool {
-        if self.cur_dir_files.len() > 0 {
-            return true;
-        }
-
-        let next_dir = self.get_next_dir();
-        if next_dir.is_none() {
-            return false;
-        }
-
-        let next_dir = next_dir.unwrap();
-        for entry in next_dir {
-            if entry.is_err() {
-                println!(
-                    "Could not read file {}, skipping",
-                    entry.unwrap().path().display()
-                );
-                continue;
-            }
-
-            let entry = entry.unwrap();
-            let path = entry.path();
-            if path.is_dir() {
-                if self.recursive {
-                    self.all_dirs.push(path.to_str().unwrap().to_string());
-                }
-            } else if path.is_file() {
-                if self.filter.apply(path.to_str().unwrap()) {
-                    self.cur_dir_files.push(path.to_str().unwrap().to_string());
-                }
-            } else {
-                println!("Skipping {}, unknown file type", path.display());
-            }
-        }
-
-        true
-    }
-}
-
-impl Iterator for FileNames {
-    type Item = String;
-
-    fn next(&mut self) -> Option<Self::Item> {
-        if let Some(dir) = self.cur_dir.take() {
-            self.all_dirs.push(dir);
-        }
-
-        if let Some(file) = self.cur_dir_files.pop() {
-            return Some(file);
-        }
-
-        loop {
-            let populated = self.populate_files();
-            if !populated {
-                return None;
-            }
-
-            if self.cur_dir_files.len() > 0 {
-                return Some(self.cur_dir_files.pop().unwrap());
-            }
-        }
-    }
-}