How to create a file in Ruby

Question

I'm trying to create a new file and things don't seem to be working as I expect them too. Here's what I've tried:

File.new "out.txt"
File.open "out.txt"
File.new "out.txt","w"
File.open "out.txt","w"

According to everything I've read online all of those should work but every single one of them gives me this:

ERRNO::ENOENT: No such file or directory - out.txt

This happens from IRB as well as a Ruby script. What am I missing?

Answer 1

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

Answer 2

Try

File.open("out.txt", "w") do |f|     
  f.write(data_you_want_to_write)   
end

without using the

File.new "out.txt"

Answer 3

尝试使用"w+"作为写入模式，而不仅仅是"w" ：

File.open("out.txt", "w+") { |file| file.write("boo!") }

Answer 4

OK, now I feel stupid. The first two definitely do not work but the second two do. Not sure how I convinced my self that I had tried them. Sorry for wasting everyone's time.

In case this helps anyone else, this can occur when you are trying to make a new file in a directory that does not exist.

Answer 5

如果目标只是创建一个文件，我看到的最直接的方法是：

 FileUtils.touch "foobar.txt"

Answer 6

The directory doesn't exist. Make sure it exists as open won't create those dirs for you.

I ran into this myself a while back.

Answer 7

File.new and File.open default to read mode ( 'r' ) as a safety mechanism, to avoid possibly overwriting a file. We have to explicitly tell Ruby to use write mode ( 'w' is the most common way) if we're going to output to the file.

If the text to be output is a string, rather than write:

File.open('foo.txt', 'w') { |fo| fo.puts "bar" }

or worse:

fo = File.open('foo.txt', 'w')
fo.puts "bar"
fo.close

Use the more succinct write :

File.write('foo.txt', 'bar')

write has modes allowed so we can use 'w' , 'a' , 'r+' if necessary.

open with a block is useful if you have to compute the output in an iterative loop and want to leave the file open as you do so. write is useful if you are going to output the content in one blast then close the file.

See the documentation for more information.

Answer 8

data = 'data you want inside the file'.

您可以使用File.write('name of file here', data)

Answer 9

You can also use constants instead of strings to specify the mode you want. The benefit is if you make a typo in a constant name, your program will raise an runtime exception.

The constants are File::RDONLY or File::WRONLY or File::CREAT . You can also combine them if you like.

Full description of file open modes on ruby-doc.org