Class: File
- Inherits:
-
Object
- Object
- File
- Defined in:
- lib/ptools.rb
Constant Summary collapse
- PTOOLS_VERSION =
The version of the ptools library.
'1.3.2'
- MSWINDOWS =
false
- WIN32EXTS =
'.{exe,com,bat}'
- IMAGE_EXT =
%w[.bmp .gif .jpg .jpeg .png]
Class Method Summary collapse
-
.binary?(file) ⇒ Boolean
Returns whether or not
file
is a binary non-image file, i.e. -
.head(filename, num_lines = 10) ⇒ Object
In block form, yields the first
num_lines
fromfilename
. -
.image?(file) ⇒ Boolean
Returns whether or not the file is an image.
-
.nl_convert(old_file, new_file = old_file, platform = 'local') ⇒ Object
Converts a text file from one OS platform format to another, ala ‘dos2unix’.
-
.null ⇒ Object
(also: null_device)
Returns the name of the null device (aka bitbucket) on your platform.
-
.sparse?(file) ⇒ Boolean
Returns whether or not
file
is a sparse file. -
.tail(filename, num_lines = 10) ⇒ Object
In block form, yields the last
num_lines
of filefilename
. -
.touch(filename) ⇒ Object
Changes the access and modification time if present, or creates a 0 byte file
filename
if it doesn’t already exist. -
.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.
-
.whereis(program, path = ENV['PATH']) ⇒ Object
Returns an array of each
program
withinpath
, or nil if it cannot be found. -
.which(program, path = ENV['PATH']) ⇒ Object
Looks for the first occurrence of
program
withinpath
.
Class Method Details
.binary?(file) ⇒ Boolean
Returns whether or not file
is a binary non-image file, i.e. executable, shared object, ect. 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, or 4096, whichever is smaller.
Example:
File.binary?('somefile.exe') # => true
File.binary?('somefile.txt') # => false
– Based on code originally provided by Ryan Davis (which, in turn, is based on Perl’s -B switch).
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# File 'lib/ptools.rb', line 90 def self.binary?(file) return false if image?(file) bytes = File.stat(file).blksize bytes = 4096 if bytes > 4096 s = (File.read(file, bytes) || "") s = s.encode('US-ASCII', :undef => :replace).split(//) ((s.size - s.grep(" ".."~").size) / s.size.to_f) > 0.30 end |
.head(filename, num_lines = 10) ⇒ Object
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# File 'lib/ptools.rb', line 224 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.
Examples:
File.image?('somefile.jpg') # => true
File.image?('somefile.txt') # => false
– The approach I used here is based on information found at en.wikipedia.org/wiki/Magic_number_(programming)
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# File 'lib/ptools.rb', line 41 def self.image?(file) bool = IMAGE_EXT.include?(File.extname(file).downcase) # Match ext bool = bmp?(file) || jpg?(file) || png?(file) || gif?(file) || tiff?(file) # Check data bool end |
.nl_convert(old_file, new_file = old_file, platform = 'local') ⇒ Object
Converts a text file from one OS platform format to another, ala ‘dos2unix’. The possible values for platform
include:
-
MS Windows -> dos, windows, win32, mswin
-
Unix/BSD -> unix, linux, bsd, osx, darwin, sunos, solaris
-
Mac -> mac, macintosh, apple
You may also specify ‘local’, in which case your CONFIG value will be used. This is the default.
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 303 def self.nl_convert(old_file, new_file = old_file, platform = 'local') unless File::Stat.new(old_file).file? raise ArgumentError, 'Only valid for plain text files' end format = nl_for_platform(platform) orig = $\ # $OUTPUT_RECORD_SEPARATOR $\ = format if old_file == new_file require 'fileutils' require 'tempfile' begin temp_name = Time.new.strftime("%Y%m%d%H%M%S") tf = Tempfile.new('ruby_temp_' + temp_name) tf.open IO.foreach(old_file){ |line| line.chomp! tf.print line } ensure tf.close if tf && !tf.closed? end File.delete(old_file) FileUtils.mv(tf.path, old_file) else begin nf = File.new(new_file, 'w') IO.foreach(old_file){ |line| line.chomp! nf.print line } ensure nf.close if nf && !nf.closed? end end $\ = orig self end |
.null ⇒ Object Also known as: null_device
Returns the name of the null device (aka bitbucket) on your platform.
Examples:
# On Linux
File.null # => '/dev/null'
# On MS Windows
File.null # => 'NUL'
– The values I used here are based on information from en.wikipedia.org/wiki//dev/null
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# File 'lib/ptools.rb', line 60 def self.null case RbConfig::CONFIG['host_os'] when /mswin|win32|msdos|mingw|windows/i 'NUL' when /amiga/i 'NIL:' when /openvms/i 'NL:' else '/dev/null' end end |
.sparse?(file) ⇒ Boolean
Returns whether or not file
is a sparse file.
A sparse file is a any file where its size is greater than the number of 512k blocks it consumes, i.e. its apparent and actual file size is not the same.
See en.wikipedia.org/wiki/Sparse_file for more information.
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# File 'lib/ptools.rb', line 423 def self.sparse?(file) stats = File.stat(file) stats.size > stats.blocks * 512 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.
Example:
File.tail('somefile.txt') # => ['This is line7', 'This is line8', ...]
If you’re looking for tail -f functionality, please use the file-tail gem instead.
– Internally I’m using a 64 chunk of memory at a time. I may allow the size to be configured in the future as an optional 3rd argument.
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# File 'lib/ptools.rb', line 254 def self.tail(filename, num_lines=10) tail_size = 2**16 # 64k chunks # MS Windows gets unhappy if you try to seek backwards past the # end of the file, so we have some extra checks here and later. file_size = File.size(filename) read_bytes = file_size % tail_size read_bytes = tail_size if read_bytes == 0 line_sep = File::ALT_SEPARATOR ? "\r\n" : "\n" buf = '' # Open in binary mode to ensure line endings aren't converted. File.open(filename, 'rb'){ |fh| position = file_size - read_bytes # Set the starting read position # Loop until we have the lines or run out of file while buf.scan(line_sep).size <= num_lines and position >= 0 fh.seek(position, IO::SEEK_SET) buf = fh.read(read_bytes) + buf read_bytes = tail_size position -= read_bytes end } lines = buf.split(line_sep).pop(num_lines) if block_given? lines.each{ |line| yield line } else lines 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 351 def self.touch(filename) if File.exist?(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 367 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 = ENV['PATH']) ⇒ Object
Returns an array of each program
within path
, or nil if it cannot be found.
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
.
Examples:
File.whereis('ruby') # => ['/usr/bin/ruby', '/usr/local/bin/ruby']
File.whereis('foo') # => nil
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# File 'lib/ptools.rb', line 166 def self.whereis(program, path=ENV['PATH']) if path.nil? || path.empty? raise ArgumentError, "path cannot be empty" end paths = [] # Bail out early if an absolute path is provided. if program =~ /^\/|^[a-z]:[\\\/]/i program += WIN32EXTS if MSWINDOWS && File.extname(program).empty? program = program.tr("\\", '/') if MSWINDOWS found = Dir[program] if found[0] && File.executable?(found[0]) && !File.directory?(found[0]) if File::ALT_SEPARATOR return found.map{ |f| f.tr('/', "\\") } else return found end else return nil end end # Iterate over each path glob the dir + program. path.split(File::PATH_SEPARATOR).each{ |dir| next unless File.exist?(dir) # In case of bogus second argument file = File.join(dir, program) # Dir[] doesn't handle backslashes properly, so convert them. Also, if # the program name doesn't have an extension, try them all. if MSWINDOWS file = file.tr("\\", "/") file += WIN32EXTS if File.extname(program).empty? end found = Dir[file].first # Convert all forward slashes to backslashes if supported if found && File.executable?(found) && !File.directory?(found) found.tr!(File::SEPARATOR, File::ALT_SEPARATOR) if File::ALT_SEPARATOR paths << found end } paths.empty? ? nil : paths.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.
Examples:
File.which('ruby') # => '/usr/local/bin/ruby'
File.which('foo') # => nil
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# File 'lib/ptools.rb', line 112 def self.which(program, path=ENV['PATH']) if path.nil? || path.empty? raise ArgumentError, "path cannot be empty" end # Bail out early if an absolute path is provided. if program =~ /^\/|^[a-z]:[\\\/]/i program += WIN32EXTS if MSWINDOWS && File.extname(program).empty? found = Dir[program].first if found && File.executable?(found) && !File.directory?(found) return found else return nil end end # Iterate over each path glob the dir + program. path.split(File::PATH_SEPARATOR).each{ |dir| dir = File.(dir) next unless File.exist?(dir) # In case of bogus second argument file = File.join(dir, program) # Dir[] doesn't handle backslashes properly, so convert them. Also, if # the program name doesn't have an extension, try them all. if MSWINDOWS file = file.tr("\\", "/") file += WIN32EXTS if File.extname(program).empty? end found = Dir[file].first # Convert all forward slashes to backslashes if supported if found && File.executable?(found) && !File.directory?(found) found.tr!(File::SEPARATOR, File::ALT_SEPARATOR) if File::ALT_SEPARATOR return found end } nil end |