Class: File

Inherits:
Object
  • Object
show all
Defined in:
lib/ptools.rb

Constant Summary collapse

PTOOLS_VERSION = 
'1.1.7'
IS_WINDOWS = 
false
IMAGE_EXT = 
%w/.bmp .gif .jpg .jpeg .png/

Class Method Summary collapse

Class Method Details

.binary?(file) ⇒ Boolean

Returns whether or not file is a binary file. Note that this is not guaranteed to be 100% accurate. It performs a “best guess” based on a simple test of the first File.blksize characters. – Based on code originally provided by Ryan Davis (which, in turn, is based on Perl’s -B switch).

Returns:

  • (Boolean) 


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# File 'lib/ptools.rb', line 66

def self.binary?(file)
   s = (File.read(file, File.stat(file).blksize) || "").split(//)
   ((s.size - s.grep(" ".."~").size) / s.size.to_f) > 0.30
end

.head(filename, num_lines = 10) ⇒ Object

In block form, yields the first num_lines from filename. In non-block form, returns an Array of num_lines



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# File 'lib/ptools.rb', line 150

def self.head(filename, num_lines=10)
   a = []
   IO.foreach(filename){ |line|
      break if num_lines <= 0
      num_lines -= 1
      if block_given?
         yield line
      else
         a << line
      end
   }
   return a.empty? ? nil : a # Return nil in block form
end

.image?(file) ⇒ Boolean

Returns whether or not the file is an image. Only JPEG, PNG, BMP and GIF are checked against.

This method does some simple read and extension checks. For a version that is more robust, but which depends on a 3rd party C library (and is difficult to build on MS Windows), see the ‘filemagic’ library, available on the RAA. – Approach used here is based on information found at en.wikipedia.org/wiki/Magic_number_(programming)

Returns:

  • (Boolean) 


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# File 'lib/ptools.rb', line 35

def self.image?(file)
   bool = IMAGE_EXT.include?(File.extname(file).downcase)      # Match ext
   bool = bmp?(file) || jpg?(file) || png?(file) || gif?(file) # Check data
   bool
end

.middle(filename, from = 10, to = 20) ⇒ Object

In block form, yields line from up to line to. In non-block form returns an Array of lines from from to to.



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# File 'lib/ptools.rb', line 167

def self.middle(filename, from=10, to=20)
   if block_given?
      IO.readlines(filename)[from-1..to-1].each{ |line| yield line }
   else
      IO.readlines(filename)[from-1..to-1]
   end
end

.nl_convert(filename, newfilename = filename, platform = "dos") ⇒ Object

Converts a text file from one OS platform format to another, ala ‘dos2unix’. Valid values for ‘format’, which are case insensitve, include:

  • MS Windows -> dos, windows, win32, mswin

  • Unix/BSD -> unix, linux, bsd

  • Mac -> mac, macintosh, apple, osx

Note that this method is only valid for an ftype of “file”. Otherwise a TypeError will be raised. If an invalid format value is received, an ArgumentError is raised.



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# File 'lib/ptools.rb', line 204

def self.nl_convert(filename, newfilename=filename, platform="dos")
   unless File.ftype(filename) == "file"
      raise TypeError, "Only valid for plain text files"
   end

   if platform =~ /dos|windows|win32|mswin/i
      format = "\cM\cJ"
   elsif platform =~ /unix|linux|bsd/i
      format = "\cJ"
   elsif platform =~ /mac|apple|macintosh|osx/i
      format = "\cM"
   else
      raise ArgumentError, "Invalid platform string"
   end

   orig = $\
   $\ = format

   if filename == newfilename
      require 'fileutils'
      require 'tempfile'

      begin
         tf = Tempfile.new('ruby_temp_' + Time.now.to_s)
         tf.open

         IO.foreach(filename){ |line|
            line.chomp!
            tf.print line
         }
      ensure
         tf.close if tf && !tf.closed?
      end
      File.delete(filename)
      FileUtils.cp(tf.path, filename)
   else
      begin
         nf = File.new(newfilename, 'w')  
         IO.foreach(filename){ |line|
            line.chomp!
            nf.print line
         }
      ensure
         nf.close if nf && !nf.closed?
      end
   end

   $\ = orig
   self
end

.null ⇒ Object

Returns the null device (aka bitbucket) on your platform. On most Unix-like systems this is ‘/dev/null’, on Windows it’s ‘NUL’, etc. – Based on information from en.wikipedia.org/wiki//dev/null



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# File 'lib/ptools.rb', line 46

def self.null
   case Config::CONFIG['host_os']
      when /mswin/i
         'NUL'
      when /amiga/i
         'NIL:'
      when /openvms/i
         'NL:'
      else
         '/dev/null'
   end
end

.tail(filename, num_lines = 10) ⇒ Object

In block form, yields the last num_lines of file filename. In non-block form, it returns the lines as an array.

Note that this method slurps the entire file, so I don’t recommend it for very large files. Also note that ‘tail -f’ functionality is not present.



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# File 'lib/ptools.rb', line 182

def self.tail(filename, num_lines=10)
   if block_given?
      IO.readlines(filename).reverse[0..num_lines-1].reverse.each{ |line|
         yield line
      }
   else
      IO.readlines(filename).reverse[0..num_lines-1].reverse
   end
end

.touch(filename) ⇒ Object

Changes the access and modification time if present, or creates a 0 byte file filename if it doesn’t already exist.



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# File 'lib/ptools.rb', line 258

def self.touch(filename)
   if File.exists?(filename)
      time = Time.now
      File.utime(time, time, filename)
   else
      File.open(filename, 'w'){}
   end
   self
end

.wc(filename, option = 'all') ⇒ Object

With no arguments, returns a four element array consisting of the number of bytes, characters, words and lines in filename, respectively.

Valid options are ‘bytes’, ‘characters’ (or just ‘chars’), ‘words’ and ‘lines’.



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# File 'lib/ptools.rb', line 274

def self.wc(filename, option='all')
   option.downcase!
   valid = %w/all bytes characters chars lines words/

   unless valid.include?(option)
      raise ArgumentError, "Invalid option: '#{option}'"
   end

   n = 0
   if option == 'lines'
      IO.foreach(filename){ n += 1 }
      return n
   elsif option == 'bytes'
      File.open(filename){ |f|
         f.each_byte{ n += 1 }
      }
      return n
   elsif option == 'characters' || option == 'chars'
      File.open(filename){ |f|
         while f.getc
            n += 1
         end
      }
      return n
   elsif option == 'words'
      IO.foreach(filename){ |line|
         n += line.split.length
      }
      return n
   else
      bytes,chars,lines,words = 0,0,0,0
      IO.foreach(filename){ |line|
         lines += 1
         words += line.split.length
         chars += line.split('').length
      }
      File.open(filename){ |f|
         while f.getc
            bytes += 1
         end
      }
      return [bytes,chars,words,lines]
   end
end

.whereis(program, path = ) ⇒ Object

In block form, yields each program within path. In non-block form, returns an array of each program within path.

On Windows, it looks for executables ending with the suffixes defined in your PATHEXT environment variable, or ‘.exe’, ‘.bat’ and ‘.com’ if that isn’t defined, which you may optionally include in program.

Returns nil if not found.



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# File 'lib/ptools.rb', line 118

def self.whereis(program, path=ENV['PATH'])
   dirs = []
   programs = [program]
   
   # If no file extension is provided on Windows, try the WIN32EXT's in turn
   if IS_WINDOWS && File.extname(program).empty?
      unless WIN32EXTS.include?(File.extname(program).downcase)
         WIN32EXTS.each{ |ext|
            programs.push(program + ext)
         }
      end
   end
   
   path.split(File::PATH_SEPARATOR).each{ |dir|
      programs.each{ |prog|
         file = File.join(dir,prog)
         file.tr!('/', File::ALT_SEPARATOR) if File::ALT_SEPARATOR
         if File.executable?(file) && !File.directory?(file)
            if block_given?
               yield file
            else
               dirs << file
            end
         end
      }
   }
   dirs.empty? ? nil : dirs.uniq
end

.which(program, path = ENV['PATH']) ⇒ Object

Looks for the first occurrence of program within path.

On Windows, it looks for executables ending with the suffixes defined in your PATHEXT environment variable, or ‘.exe’, ‘.bat’ and ‘.com’ if that isn’t defined, which you may optionally include in program.

Returns nil if not found.



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# File 'lib/ptools.rb', line 79

def self.which(program, path=ENV['PATH'])
   programs = [program]
   
   # If no file extension is provided on Windows, try the WIN32EXT's in turn
   if IS_WINDOWS && File.extname(program).empty?
      unless WIN32EXTS.include?(File.extname(program).downcase)
         WIN32EXTS.each{ |ext|
            programs.push(program + ext)
         }
      end
   end
   
   # Catch the first path found, or nil
   location = catch(:done){
      path.split(File::PATH_SEPARATOR).each{ |dir|
         programs.each{ |prog|
            f = File.join(dir, prog)
            if File.executable?(f) && !File.directory?(f)
               location = File.join(dir, prog)
               location.tr!('/', File::ALT_SEPARATOR) if File::ALT_SEPARATOR
               throw(:done, location)
            end
         }
      }
      nil # Evaluate to nil if not found
   }

   location
end