dcat: Concatenate File(s) to Standard Output or File

A cat command-line and library implementation in Dart, inspired by the Write command-line apps sample code.

Synopsis

dcat copies each file, or standard input if none are given, to standard output or file.

Command-Line Usage

dcat --help

Usage: dcat [OPTION]... [FILE]...
Concatenate FILE(s) to standard output.

With no FILE, or when FILE is -, read standard input.

  -A, --show-all                 equivalent to -vET
  -b, --number-nonblank          number nonempty output lines, overrides -n
  -e, --show-nonprinting-ends    equivalent to -vE
  -E, --show-ends                display $ at end of each line
  -h, --help                     display this help and exit
  -n, --number                   number all output lines
  -t, --show-nonprinting-tabs    equivalent to -vT
  -T, --show-tabs                display TAB characters as ^I
  -s, --squeeze-blank            suppress repeated empty output lines
      --version                  output version information and exit
  -v, --show-nonprinting         use ^ and U+ notation, except for LFD and TAB

Examples:
  dcat f - g  Output f's contents, then standard input, then g's contents.
  dcat        Copy standard input to standard output.

Compile Standalone Application

*nix

dart compile exe -o bin/dcat bin/dcat.dart

Windows

dart compile exe bin/dcat.dart

Library Usage

import 'package:dcat/dcat.dart';

final result = await cat(['path/to/file', 'path/to/otherfile]'], File('path/to/outfile'));
if (result.exitCode == exitFailure) {
  for (final message in result.messages) {
    print("Error: $message");
  }
}

The cat function supports the following parameters:

Parameter	Description	Type
paths	The file paths.	String[]
output	The standard output or file.	IOSink or File
input	The standard input.	Stream<List<int>>?
log	The log for debugging.	List<String>?
showEnds	Same as -e	bool
numberNonBlank	Same as -b	bool
showLineNumbers	Same as -n	bool
showTabs	Same as -T	bool
squeezeBlank	Same as -s	bool
showNonPrinting	Same as -v	bool

• paths and output are required.
• output should be an IOSink like stdout or a File.
• input can be stdin.
• log is used for debugging/testing purposes.

The remaining optional parameters are similar to the GNU cat utility.

A CatResult object is returned which contains the exitCode (exitSuccess or exitFailure) and error messages if any:

final result = await cat(['path/to/file'], stdout);
if (result.exitCode == exitSuccess) {
  ...
}

Differences from GNU cat

• No binary file support.
• A line is considered terminated by either a CR (carriage return), a LF (line feed), a CR+LF sequence (DOS line ending).
• A line ending is automatically appended to the last line of any read file.
• The U+ notation is used instead of M- for non-printing characters.