I have this little program I write in ruby. I found a nice piece of code here, on SO, to find and replace something in a file, but it doesn't seems to work.
Here's the code:
#!/usr/bin/env ruby
DOC = "test.txt"
FIND = /,,^M/
SEP = "\n"
#make substitution
File.read(DOC).gsub(FIND, SEP)
#Check if the line already exist
unique_lines = File.readlines(DOC).uniq
#Save the result in a new file
File.open('test2.txt', 'w') { |f| f.puts(unique_lines) }
Thanks everybody !
I skip the check you make to see if the line already exists and usually go with something like this (here I want to replace 'FOO' with 'BAR'):
full_path_to_read = File.expand_path('~/test1.txt')
full_path_to_write = File.expand_path('~/test2.txt')
File.open(full_path_to_read) do |source_file|
contents = source_file.read
contents.gsub!(/FOO/, 'BAR')
File.open(full_path_to_write, "w+") { |f| f.write(contents) }
end
The use of expand_path is also probably a bit pedantic here, but I like it just so that I don't accidentally clobber some file I didn't mean to.
Related
Below is the piece of code that is supposed read the directory and for each file entry prints the first row of the file. The issue is x is not visible so file is not being parsed.
Dir.foreach("C:/fileload/src") do |file_name|
x = file_name
puts x
f = File.open("C:/fileload/src/" +x)
f.readlines[1..1].each do |line|
puts line
end
end
Why are you assigning x to file_name? You can use file_name directly. And if you are only reading the first line of the file, why not try this?
#!/usr/bin/ruby
dir = "C:/fileload/src"
Dir.foreach(dir) do |file_name|
full = File.join(dir, file_name)
if File.file?(full)
f = File.open(full)
puts f.first
f.close
end
end
You should use File.join to safely combine paths in Ruby. I also checked that you are opening a file using the File.file? method.
You have no visibility issue with x. You should be using File::join or Pathname#+ to build your file paths. You should exclude non-files from consideration. You're selecting the second line, not the first with [1..1]. Here's a cleaner correct replacement for your sample code.
dir = "C:/fileload/src"
Dir.foreach(dir).
map { |fn| File.join(dir,fn) }.
select { |fn| File.file?(fn) }.
each { |fn| puts File.readlines(fn).first }
post '/upload' do
unless params[:file] && (tmpfile = params[:file][:tempfile]) && (name = params[:file][:filename])
return haml(:upload)
end
time = Time.now.to_s
time.gsub!(/\s/, '')
name = time + name
while blk = tmpfile.read(65536)
File.open(File.join(Dir.pwd,"public/uploads", name), "wb") { |f| f.write(tmpfile.read) }
end
'success'
end
Everything goes where expected the files just end up being corrupted.
This bit looks really funky:
while blk = tmpfile.read(65536)
File.open(File.join(Dir.pwd,"public/uploads", name), "wb") { |f| f.write(tmpfile.read) }
end
I'm guessing you're trying to read your tempfile a 65536-byte block at a time, and then write those blocks successively to your destination file. But you never write blk, which is the first block you read; you write the rest of the file (tempfile.read) instead. And even if this loop did write blocks like it should, it opens the file anew for each block, overwriting the old contents! Anyway, I suspect you meant something like this:
File.open(File.join(Dir.pwd,"public/uploads", name), "wb") do |f|
while(blk = tempfile.read(65536))
f.write(blk)
end
end
That said, if you've got the file as a temp file (presumably already on your local file system), maybe all you need to do is move that file? It'll go way faster if that's the case - if the source and destination are on the same disk, it's just a matter of swapping some file system pointers, rather than copying all that data.
Hope that helps!
The code opens and replaces the file during every iteration of the loop, which causes part of the problem. The code also reads the tmpfile into blk then throws that data away. Time.now.to_s contains colons, which is the path separator on Mac OS X, and could cause a problem on OS X. The user-supplied filename could contain some bad stuff like .. which may allow users to overwrite files. Try this instead:
require 'pathname'
require 'zaru'
post '/upload' do
unless tmpfile = params[:file].try(:[], :tempfile)
return haml(:upload)
end
name = Zaru.sanitize!("#{Time.now.to_i}#{params[:file][:filename]}")
Pathname.pwd.join("public/uploads", name).open("wb") do |f|
while blk = tmpfile.read(65536)
f.write(blk)
end
end
'success'
end
You should also make sure that the filename doesn't end in something nefarious, like .js or .css, which could be exploited.
I am kind of a newbie to Ruby, I am working out some katas and I stuck on this silly problem. I need to copy the content of 1 file to a new file in 1 line of code
First try:
File.open(out, 'w').write(File.open(in).read)
Nice, but it's wrong I need to close the files:
File.open(out, 'w') { |outf| outf.write(File.open(in).read) }
And then of course close the read:
File.open(out, 'w') { |outf| File.open(in) { |inf| outf.write(outf.read)) } }
This is what I come up with, but it does not look like 1 line of code to me :(
Ideas?
Regards,
Ruby 1.9.3 and later has a
File.write(name, string, [offset], open_args)
command that allows you to write a file directly. name is the name of the file, string is what you want to write, and the other arguments are above my head.
Some links for it: https://github.com/ruby/ruby/blob/ruby_1_9_3/NEWS , http://bugs.ruby-lang.org/issues/1081 (scroll to the bottom).
There are many ways. You could simply invoke the command line for example:
`cp path1 path2`
But I guess you're looking for something like:
File.open('foo.txt', 'w') { |f| f.write(File.read('bar.txt')) }
You can do the following:
File.open(out_file, "w") {|f| f.write IO.read(in_file)}
You can try:
IO.binwrite('to-filename', IO.binread('from-filename'))
Check the ruby docs:
IO::binwrite & IO::binread
I need to read the data out of database and then save it in a text file.
How can I do that in Ruby? Is there any file management system in Ruby?
Are you looking for the following?
File.open(yourfile, 'w') { |file| file.write("your text") }
You can use the short version:
File.write('/path/to/file', 'Some glorious content')
It returns the length written; see ::write for more details and options.
To append to the file, if it already exists, use:
File.write('/path/to/file', 'Some glorious content', mode: 'a')
This is preferred approach in most cases:
File.open(yourfile, 'w') { |file| file.write("your text") }
When a block is passed to File.open, the File object will be automatically closed when the block terminates.
If you don't pass a block to File.open, you have to make sure that file is correctly closed and the content was written to file.
begin
file = File.open("/tmp/some_file", "w")
file.write("your text")
rescue IOError => e
#some error occur, dir not writable etc.
ensure
file.close unless file.nil?
end
You can find it in documentation:
static VALUE rb_io_s_open(int argc, VALUE *argv, VALUE klass)
{
VALUE io = rb_class_new_instance(argc, argv, klass);
if (rb_block_given_p()) {
return rb_ensure(rb_yield, io, io_close, io);
}
return io;
}
The Ruby File class will give you the ins and outs of ::new and ::open but its parent, the IO class, gets into the depth of #read and #write.
Zambri's answer found here is the best.
File.open("out.txt", '<OPTION>') {|f| f.write("write your stuff here") }
where your options for <OPTION> are:
r - Read only. The file must exist.
w - Create an empty file for writing.
a - Append to a file.The file is created if it does not exist.
r+ - Open a file for update both reading and writing. The file must exist.
w+ - Create an empty file for both reading and writing.
a+ - Open a file for reading and appending. The file is created if it does not exist.
In your case, w is preferable.
For those of us that learn by example...
Write text to a file like this:
IO.write('/tmp/msg.txt', 'hi')
BONUS INFO ...
Read it back like this
IO.read('/tmp/msg.txt')
Frequently, I want to read a file into my clipboard ***
Clipboard.copy IO.read('/tmp/msg.txt')
And other times, I want to write what's in my clipboard to a file ***
IO.write('/tmp/msg.txt', Clipboard.paste)
*** Assumes you have the clipboard gem installed
See: https://rubygems.org/gems/clipboard
To destroy the previous contents of the file, then write a new string to the file:
open('myfile.txt', 'w') { |f| f << "some text or data structures..." }
To append to a file without overwriting its old contents:
open('myfile.txt', "a") { |f| f << 'I am appended string' }
This is a newbie question as I am attempting to learn Ruby by myself, so apologies if it sounds like a silly question!
I am reading through the examples of why's (poignant) guide to ruby and am in chapter 4. I typed the code_words Hash into a file called wordlist.rb
I opened another file and typed the first line as require 'wordlist.rb' and the rest of the code as below
#Get evil idea and swap in code
print "Enter your ideas "
idea = gets
code_words.each do |real, code|
idea.gsub!(real, code)
end
#Save the gibberish to a new file
print "File encoded, please enter a name to save the file"
ideas_name = gets.strip
File::open( 'idea-' + ideas_name + '.txt', 'w' ) do |f|
f << idea
end
When I execute this code, it fails with the following error message:
C:/MyCode/MyRubyCode/filecoder.rb:5: undefined local variable or method `code_words' for main:Object (NameError)
I use Windows XP and Ruby version ruby 1.8.6
I know I should be setting something like a ClassPath, but not sure where/how to do so!
Many thanks in advance!
While the top-level of all files are executed in the same context, each file has its own script context for local variables. In other words, each file has its own set of local variables that can be accessed throughout that file, but not in other files.
On the other hand, constants (CodeWords), globals ($code_words) and methods (def code_words) would be accessible across files.
Some solutions:
CodeWords = {:real => "code"}
$code_words = {:real => "code"}
def code_words
{:real => "code"}
end
An OO solution that is definitely too complex for this case:
# first file
class CodeWords
DEFAULT = {:real => "code"}
attr_reader :words
def initialize(words = nil)
#words = words || DEFAULT
end
end
# second file
print "Enter your ideas "
idea = gets
code_words = CodeWords.new
code_words.words.each do |real, code|
idea.gsub!(real, code)
end
#Save the gibberish to a new file
print "File encoded, please enter a name to save the file"
ideas_name = gets.strip
File::open( 'idea-' + ideas_name + '.txt', 'w' ) do |f|
f << idea
end
I think the problem might be that the require executes the code in another context, so the runtime variable is no longer available after the require.
What you could try is making it a constant:
CodeWords = { :real => 'code' }
That will be available everywhere.
Here is some background on variable scopes etc.
I was just looking at the same example and was having the same problem.
What I did was change the variable name in both files from code_words to $code_words .
This would make it a global variable and thus accesible by both files right?
My question is: wouldn't this be a simpler solution than making it a constant and having to write CodeWords = { :real => 'code' } or is there a reason not to do it ?
A simpler way would be to use the Marshal.dump feature to save the code words.
# Save to File
code_words = {
'starmonkeys' => 'Phil and Pete, those prickly chancellors of the New Reich',
'catapult' => 'chucky go-go', 'firebomb' => 'Heat-Assisted Living',
'Nigeria' => "Ny and Jerry's Dry Cleaning (with Donuts)",
'Put the kabosh on' => 'Put the cable box on'
}
# Serialize
f = File.open('codewords','w')
Marshal.dump(code_words, f)
f.close
Now at the beginning of your file you would put this:
# Load the Serialized Data
code_words = Marshal.load(File.open('codewords','r'))
Here's the easy way to make sure you can always include a file that's in the same directory as your app, put this before the require statement
$:.unshift File.dirname(__FILE__)
$: is the global variable representing the "CLASSPATH"