I'm new to Ruby, and I am writing a test program just to get some of the features down. Here is the program
#!/usr/bin/env ruby
class FileManager
def read_file(filename)
return nil unless File.exist?(filename)
File.read(filename)
end
end
if __FILE__ == $0
fm = FileManager.new
puts "What file would you like to open?"
fname = gets
puts fm.read_file fname
end
As you can see, it is very simple. If I comment the first line of the read_file method, I get this error
No such file or directory - /Users/macuser/Projects/Aptana\ Studio\ 3\ Workspace/Ruby\ Test/text (Errno::ENOENT)
from /Users/macuser/Projects/Aptana Studio 3 Workspace/Ruby Test/ruby.rb:6:in `read_file'
from /Users/macuser/Projects/Aptana Studio 3 Workspace/Ruby Test/ruby.rb:15:in `<main>'
when I run the program and use this file: /Users/macuser/Projects/Aptana\ Studio\ 3\ Workspace/Ruby\ Test/text
However, if I run cat /Users/macuser/Projects/Aptana\ Studio\ 3\ Workspace/Ruby\ Test/text, it outputs Hello, world!, as it should.
I don't believe it's a permissions issue because I own the folder, but just in case I've tried running the program as root. Also, I have made sure that fname is the actual name of the file, not nil. I've tried both escaped and unescaped versions of the path, along with just text or the full path. I know for a fact the file exists, so why is Ruby giving me this error?
With gets filename the filename includes a newline \n.
You have to remove it in your filename:
gets filename
p filename #"test.rb\n"
p File.exist?(filename) #false
p File.exist?(filename.chomp) #true
(And you don't need to mask the spaces)
It looks like you're shell-escaping your spaces even though gets does not go through a shell. You want to enter "/Users/macuser/Projects/Aptana Studio 3 Workspace/Ruby Test/text" instead of "/Users/macuser/Projects/Aptana\ Studio\ 3\ Workspace/Ruby\ Test/text".
Related
I have a beginners coding task, first step is my program "should prompt the user to enter a filename of a file that contains the following information:" There's already pre-made code to work on, a "music_player.rb" (where I have to write the code) and "albums.text" (which is the file I want to read from)
I know a_file = File.new("mydata.txt", "r") is to read from file. I'm trying to do:
file_name = gets()
a_file = File.new("#{file_name}" , "r") # (line 13)
I keep getting error
music_player_with_menu.rb:13:in `initialize': No such file or directory # rb_sysopen - albums.txt (Errno::ENOENT)
when I enter albums.txt. If I just remove gets and have File.new("albums.txt" , "r") it works. I'm not sure what I'm doing wrong.
Trying to read from mydata.txt\n is going to raise an exception unless the filename actually ends in \n, which is rarely the case. This is because you're using #gets, which includes the newline character(s) from the user pressing RETURN or ENTER.
When you read from STDIN, you will get a line-ending (e.g. \n on *nix, and \r\n on Windows). So, when you call #gets, you almost always need to call String#chomp on the result.
file_name = gets
#=> "foo\n"
file_name = gets.chomp
#=> "foo"
Facing below issue eventhough the file is present in the folder.
H:\Ruby_test_works>ruby hurrah.rb
hurrah.rb:7:in `read': No such file or directory # rb_sysopen - H:/Ruby_
test_works/SVNFolders.txt (Errno::ENOENT)
from hurrah.rb:7:in `block in <main>'
from hurrah.rb:4:in `each_line'
from hurrah.rb:4:in `<main>'
Input file (input.txt) Columns are tab separated.
10.3.2.021.asd 10.3.2.041.def SVNFolders.txt
SubversionNotify Subversionweelta post-commit.bat
Commit message still rake customemail.txt
mckechney.com yahoo.in ReadMe.txt
Code :
dir = 'H:/Ruby_test_works'
file = File.open("#{dir}/input.txt", "r")
file.each_line do |line|
initial, final, file_name = line.split("\t")
#puts file_name
old_value = File.read("#{dir}/#{file_name}")
replace = old_value.gsub( /#{Regexp.escape(initial)}, #{Regexp.escape(final)}/)
File.open("#{dir}/#{file_name}", "w") { |fi| fi.puts replace }
end
I have tried using both forward and backward slashes but no luck. What I'm missing, not sure. Thanks.
puts file_name gives the below values
SVNFolders.txt
post-commit.bat
customemail.txt
ReadMe.txt
The file_name contains the newline character \n at the end, which won't get printed but messes up the path. You can fix the issue by stripping the line first:
initial, final, file_name = line.strip.split("\t")
When debugging code, be careful with puts. Quoting its documentation reveals an ugly truth:
Writes the given object(s) to ios. Writes a newline after any that do not already end with a newline sequence.
Another way to put this is to say it ignores (potential) newlines at the end of the object(s). Which is why you never saw that the file name actually was SVNFolders.txt\n.
Instead of using puts, you can use p when troubleshooting issues. The very short comparison between the two is that puts calls to_s and adds a newline, while p calls inspect on the object. Here is a bit more details about the differences: http://www.garethrees.co.uk/2013/05/04/p-vs-puts-vs-print-in-ruby/
Sometimes the issue is not the file, but the path to the file. Consider compare the file path with what you think the file path is with something like:
File.expand_path('my_file.rb')
So, I'm relatively new to programming, and I have started working with ruby. I am going through "Learn how to code the hard way: Ruby" and I am on exercise 15; the beginning of file reading. I have copied the code they provided word for word, literally copy and pasted it to make sure, but I am getting the same error. I've googled the error, but to no avail. I have the .rb file in the same directory as the .txt file I'm trying to read. Here is my code.
filename = ARGV.first
prompt = "> "
txt = File.open(filename)
puts "Here's your file: #{filename}"
puts txt.read()
puts "I'll also ask you to type it again:"
print prompt
file_again = STDIN.gets.chomp()
txt_again = File.open(file_again)
puts txt_again.read()
The error I keep getting it this:
ex15.rb:19:in 'initialize': No such file of directory - ex15.txt <Errno::ENOENT>
from ex15.rb:4:in 'open'
from ex15.rb:4:in '<main>'
command to run it:
ruby ex15.rb ex15.txt
Any help is appreciated. Thanks
When you don't specify the mode argument for File.open(), the default is 'r', which stands for read. And to read a file, it has to exist already. The error message is telling you that there is no file named 'ex15.txt' in the current directory for ruby to read.
To get rid of the error, create a file called ex15.txt in the current directory, and type 'hello world' in the file.
I'm trying to write a program which substitutes a string.
require File.join(APP_ROOT, 'lib', 'main.rb')
files_names = Dir.entries("../DeSpacer")
files_names.each do |file_name|
File.open("#{file_name}", "w") do |text|
text.each {|line| line.gsub!(/\.\s{2,}/, "\.\s")}
end
end
I keep getting a
Permission denied -. (ERRNO::EACCES)
Can you explain what I am doing wrong?
The initial problem is that you're only opening the file for writing ('w'), and not reading, and thus receiving the exception.
As the comments above mention, there are other issues with the code as well.
This answer gives a more typical way to do what you're trying to do.
As mentioned in another answer to the same question, Ruby also has a command line shortcut inherited from Perl which makes things like this trivial:
ruby -pi.bak -e "gsub(/oldtext/, 'newtext')" *.txt
This will edit a file or files in place, backing up the previous version with a suffix of '.bak'.
From Programming Ruby:
-i [extension}
' Edits ARGV files in place. For each file named in ARGV, anything you write to
standard output will be saved back as the contents of that file. A backup copy of
the file will be made if extension is supplied.
% ruby -pi.bak -e "gsub(/Perl/, 'Ruby')" *.txt
I want to be able to read a currently open file. The test.rb is sending its output to test.log which I want to be able to read and ultimately send via email.
I am running this using cron:
*/5 * * * /tmp/test.rb > /tmp/log/test.log 2>&1
I have something like this in test.rb:
#!/usr/bin/ruby
def read_file(file_name)
file = File.open(file_name, "r")
data = file.read
file.close
return data
end
puts "Start"
puts read_file("/tmp/log/test.log")
puts "End"
When I run this code, it only gives me this output:
Start
End
I would expect the output to be something like this:
Start
Start (from the reading of the test.log since it should have the word start already)
End
Ok, you're trying to do several things at once, and I suspect you didn't systematically test before moving from one step to the next.
First we're going to clean up your code:
def read_file(file_name)
file = File.open(file_name, "r")
data = file.read
file.close
return data
end
puts "Start"
puts read_file("/tmp/log/test.log")
puts "End"
can be replaced with:
puts "Start"
puts File.read("./test.log")
puts "End"
It's plain and simple; There's no need for a method or anything complicated... yet.
Note that for ease of testing I'm working with a file in the current directory. To put some content in it I'll simply do:
echo "foo" > ./test.log
Running the test code gives me...
Greg:Desktop greg$ ruby test.rb
Start
foo
End
so I know the code is reading and printing correctly.
Now we can test what would go into the crontab, before we deal with its madness:
Greg:Desktop greg$ ruby test.rb > ./test.log
Greg:Desktop greg$
Hmm. No output. Something is broken with that. We knew there was content in the file previously, so what happened?
Greg:Desktop greg$ cat ./test.log
Start
End
Cat'ing the file shows it has the "Start" and "End" output of the code, but the part that should have been read and output is now missing.
What happening is that the shell truncated "test.log" just before it passed control to Ruby, which then opened and executed the code, which opened the now empty file to print it. In other words, you're asking the shell to truncate (empty) it just before you read it.
The fix is to read from a different file than you're going to write to, if you're trying to do something with the contents of it. If you're not trying to do something with its contents then there's no point in reading it with Ruby just to write it to a different file: We have cp and/or mv to do those things for us witout Ruby being involved. So, this makes more sense if we're going to do something with the contents:
ruby test.rb > ./test.log.out
I'll reset the file contents using echo "foo" > ./test.log, and cat'ing it showed 'foo', so I'm ready to try the redirection test again:
Greg:Desktop greg$ ruby test.rb > ./test.log.out
Greg:Desktop greg$ cat test.log.out
Start
foo
End
That time it worked. Trying it again has the same result, so I won't show the results here.
If you're going to email the file you could add that code at this point. Replacing the puts in the puts File.read('./test.log') line with an assignment to a variable will store the file's content:
contents = File.read('./test.log')
Then you can use contents as the body of a email. (And, rather than use Ruby for all of this I'd probably do it using mail or mailx or pipe it directly to sendmail, using the command-line and shell, but that's your call.)
At this point things are in a good position to add the command to crontab, using the same command as used on the command-line. Because it's running in cron, and errors can happen that we'd want to know about, we'd add the 2>&1 redirect to capture STDERR also, just as you did before. Just remember that you can NOT write to the same file you're going to read from or you'll have an empty file to read.
That's enough to get your app working.
class FileLineRead
File.open("file_line_read.txt") do |file|
file.each do |line|
phone_number = line.gsub(/\n/,'')
user = User.find_by_phone_number(line)
user.destroy unless user.nil?
end
end
end
open file
read line
DB Select
DB Update
In the cron job you have already opened and cleared test.log (via redirection) before you have read it in the Ruby script.
Why not do both the read and write in Ruby?
It may be a permissions issue or the file may not exist.
f = File.open("test","r")
puts f.read()
f.close()
The above will read the file test. If the file exists in the current directory
The problem is, as I can see, already solved by Slomojo. I'll only add:
to read and print a text file in Ruby, just:
puts File.read("/tmp/log/test.log")