Ruby - How to Write a New File with Output from Script

Ruby - How to write a new file with output from script

Outputting to a new file can be done like this (don't forget the second parameter):

output = File.open( "outputfile.yml","w" )
output << "This is going to the output file"
output.close

So in your example, you could do this :

File.open("us_cities.yml", "r+") do |file|
  while line = file.gets
    "do find a replace"
  end
  output = File.open( "outputfile.yml", "w" )
  output << "Here I am writing to a new file"
  output.close      
end

If you want to append to the file, make sure you put the opening of the output file outside of the loop.

How to create a file in Ruby

Use:

File.open("out.txt", [your-option-string]) {|f| f.write("write your stuff here") }

where your options 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.

OR you could have:

out_file = File.new("out.txt", "w")
#...
out_file.puts("write your stuff here")
#...
out_file.close

How to write to file in Ruby?

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.

How do I save the text of puts in Ruby to a txt file?

There are ways to save the output of a script to a file without having to modify every puts in the script.

The easiest is to route the output at the command-line using redirection. Running a script with > some_file at the of the command will route all STDOUT to the file. Similarly, using > some_file 2>&1 will route both STDOUT and STDERR to the same file. This won't capture anything typed in at a gets as the code waits for input though, because that won't count as program output.

If you don't mind changing your code a little, you can temporarily change the interpreter's idea of what STDOUT is by reassigning it to a file:

old_stdout = $stdout
File.open('output.txt', 'w') do |fo|
  $stdout = fo

  # ----
  # your code goes here
  puts "hello world"
  # ----

end
$stdout = old_stdout

Run that, then look at the file "output.txt" and you'll see "hello world", even though we didn't print to the file-handle fo directly, like we would normally do using fo.puts.

There are a variety of ways of doing the same thing but they amount to pointing STDOUT or STDERR somewhere else, writing to them, then resetting them.

Typically, if we intend from the start to output to a file, then we should use a File.open block:

File.open('output.txt', 'w') do |fo|
  fo.puts "hello world"
end

The benefit of that is the file will be closed automatically when the block exits.

How do I write to a file in Ruby?

The correct way:

file = File.join(File.dirname(__FILE__), 'test.txt')
File.open(file, 'w') { |f| f.puts 'hello' }

__FILE__ is the path to the file containing the above code, and since, your test.txt resides in the same directory as write_to_file.rb, this should work, regardless of which directory you are in, on your machine.

Also, note that, I have used puts method instead of write, since I prefer newlines. :)

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Whats wrong with your Code (probably):

When you use test.txt, then the path is relative to the directory from where you are running your write_to_file.rb script. For example, if you run write_to_file.rb from your home directory, then test.txt will imply ~/test.txt.

How to write output file of ruby code into specific directory/location?

Because \ in strings are special characters so you should use \\ (double backslashes) to get a single backslash. But there is a better way, you don't need to deal with backslashes at all:

fname = File.join("C:", "repo", "cookbooks", "abc", "recipes", "add.rb")

How to print output of ruby function to a file

The problem is that ./program.rb > output.txt redirects the output as well as the prompts for input into the text file, so you can't see what you're doing. You have several options:

1. Use STDERR.puts to prompt for input, so it doesn't get caught by the redirection. This is my preferred method.
2. Use ARGV to pass input to your program. This is a good option if you think the program isn't too hard to use without prompts.
3. Use File.open to create an output file and write to it directly. Sometimes this is the most sensible option, but usually you want to do one of the first two.

Write Ruby Output to a File

Just change variable name f to ff, and do:

entry = nil
if mod > (Time.now - 86400)
   found_completed = true
   entry = "#{modtime} - #{project} - #{wordcount}"
end
open('/path/to/newfile.txt', 'a+') {|ff| ff.puts entry }

or:

if mod > (Time.now - 86400)
   found_completed = true
   entry = "#{modtime} - #{project} - #{wordcount}"
   open('/path/to/newfile.txt', 'a+') {|ff| ff.puts entry }
end

To open file for write/read operations, and then to use it, do:

fstore = open '/path/to/newfile.txt', 'a+'
...
fstore.puts entry
...
fstore.close

Ruby redirect output to file

You either can write to a file explicitly (open file and write to it)

file = File.open('target.file', 'w') do |file|
  File.foreach('links.txt') do |li|
    file.puts(li) if li['PersonNight']
  end
end

Or redirect from outside your script, using regular unix machinery

ruby my_script.rb > target.file

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