This question already has answers here:
What are the Ruby File.open modes and options?
(2 answers)
Closed 6 years ago.
I have a file in which one I want to store some datas.
Using IRB, I can add different lines in the file. However, using a Ruby script writen in a file, I have issues.
I can write a line, it is stored as it should be, but when I re launch the script and re use the method, it overwrites what was in the file instead of adding content at the next line.
def create_new_account
puts "Set the account's name"
#account_name = gets
puts "New account's name: #{#account_name}
open("accounts.txt","w+") do |account_file|
account_file.write "ac;#{#account_name}\n"
end
end
I had a look to the different parameters of the method open, but seems like it's not there.
Moreover, I tried puts instead of write, but there is no difference, always the same problem.
Could someone help me understand what is wrong with the code?
Thanks
Try opening the file in append mode like so
open('accounts.txt', 'a+')
otherwise the file is opened so as to overwrite the existing data.
"a" - Write-only, each write call appends data at end of file.
Creates a new file for writing if file does not exist.
Related
I am doing a demo command line project in Ruby. The structure is like this:
/ROOT_DIR
init.rb
/SCRIPT_DIR
(other scripts and files)
I want users to only go into the application using init.rb, but as it stands, anyone can go into the sub-folder and call other ruby scripts directly.
Questions:
What ways can above scenario be prevented?
If I was to use directory permissions, would it get reset when running the code from a Windows machine to on Linux machine?
Is there anything that can be included in Ruby files itself to prevent it from being directly called from OS command line?
You can't do this with file permissions, since the user needs to read the files; removing the read permission means you can't include it either. Removing the execute permission is useful to signal that these file aren't intended to be executed, but won't prevent people from typing ruby incl.rb.
The easiest way is probably to set a global variable in the init.rb script:
#!/usr/bin/env ruby
FROM_INIT = true
require './incl.rb'
puts 'This is init!'
And then check if this variable is defined in the included incl.rb file:
unless defined? FROM_INIT
puts 'Must be called from init.rb'
exit 0
end
puts 'This is incl!'
A second method might be checking the value of $PROGRAM_NAME in incl.rb; this stores the current program name (like argv[0] in many other languages):
unless $PROGRAM_NAME.end_with? 'init.rb'
puts 'Must be called from init.rb'
exit 0
end
I don't recommend this though, as it's not very future-proof; what if you want to rename init.rb or make a second script?
This question already has answers here:
How to write to file in Ruby?
(7 answers)
Closed 7 years ago.
I want to create a temp file:
def create_file
FileUtils.mkdir_p('/var/log/my_app')
tmp_file = '/var/log/my_app/tmp_file'
File.open(tmp_file, 'w') do |file|
file.write 'test'
end
end
Here I am sure that the /var/log/my_app path exists. But after I run this method, I can't find a file named tmp_file under that path.
And there wasn't any error, too.
I think you would do better using Ruby's TempFile class and perhaps even Ruby's temp dir as suggested in this article: Quick tips for doing IO with Ruby.
I think you will find the article helpful. I believe it will make your approach easier - especially regarding deleting the file once you're done with it.
I don't see any error in your code. If you don't get any exception, the file must have been created, if this function has been executed.
I suggest that you make a test at the end of create_file:
if File.file?
puts "File has been created"
else
fail "File is not there!"
end
If you see "File has been created", but the file is still missing, something must have erased it before you had time to check its presence. If you see "File is not there!", something weird is going on and I would call an exorcist. If you don't see any message, it means that your function has not been executed.
I am trying to open a non existent file and write to it, however when I run the script, no file is being created.
Here is the line of code
File.open("valid_policies.txt", 'a+').write(policy_number.to_s + "\n")
Instead of using .write try this instead:
File.open("valid_policies.txt", 'a+') {|f| f.write(policy_number.to_s + "\n") }
You're using:
File.open("valid_policies.txt", 'a+').write(policy_number.to_s + "\n")
That's a non-block form of open which doesn't automatically close the file. That means the data is most likely not being written to the file but is sitting in the IO buffer waiting to be flushed/synced. You could add a close but that only propagates non-idiomatic code.
Instead you can use:
File.write("valid_policies.txt", policy_number.to_s + "\n")
File.write automatically creates then writes to the file then closes it. It will overwrite existing files though.
If you aren't sure whether the file exists and want to create it if it doesn't, or append to it, then you use File.open with the a mode instead of a+. From the mode documentation:
"a" Write-only, each write call appends data at end of file.
Creates a new file for writing if file does not exist.
Using a+ will work but it unnecessarily opens the file for reading also. Don't do that unless you're sure that's what you have to do.
If I needed to append I'd use:
File.open('valid_policies.txt', 'a') do |fa|
fa.puts policy_number
end
That's idiomatic Ruby. puts will automatically "stringify" policy_number if it has a to_s method, which it should have since you're already calling it, and it'll also automatically add the trailing "\n" if it doesn't exist at the end of the string. Also, using the block form of open will automatically close the file when the block exists, which is smart house-keeping.
I have a file called backup.lua, which the program should write to every so often in order to backup its status, in case of a failure.
The problem is that the program writes the backup.lua file completely fine first-time round, but any other times it refuses to write to the file.
I tried removing the file while the program was still open but Windows told me that the file was in use by 'CrysisWarsDedicatedServer.exe', which is the program. I have told the host Lua function to close the backup.lua file, so why isn't it letting me modify the file at will after it has been closed?
I can't find anything on the internet (Google actually tried to correct my search) and the secondary programmer on the project doesn't know either.
So I'm wondering if any of you folks know what we are doing wrong here?
Host function code:
function ServerBackup(todo)
local write, read;
if todo=="write" then
write = true;
else
read = true;
end
if (write) then
local source = io.open(Root().."Mods/Infinity/System/Read/backup.lua", "w");
System.Log(TeamInstantAction:GetTeamScore(2).." for 2, and for 1: "..TeamInstantAction:GetTeamScore(1))
System.LogAlways("[System] Backing up serverdata to file 'backup.lua'");
source:write("--[[ The server is dependent on this file; editing it will lead to serious problems.If there is a problem with this file, please re-write it by accessing the backup system ingame.--]]");
source:write("Backup = {};Backup.Time = '"..os.date("%H:%M").."';Backup.Date = '"..os.date("%d/%m/%Y").."';");
source:write(XFormat("TeamInstantAction:SetTeamScore(2, %d);TeamInstantAction:SetTeamScore(1, %d);TeamInstantAction:UpdateScores();",TeamInstantAction:GetTeamScore(2), TeamInstantAction:GetTeamScore(1) ));
source:close();
for i,player in pairs(g_gameRules.game:GetPlayers() or {}) do
if (IsModerator(player)) then
CMPlayer(player, "[!backup] Completed server backup.");
end
end
end
--local source = io.open(Root().."Mods/Infinity/System/Read/backup.lua", "r"); Can the file be open here and by the Lua scriptloader too?
if (read) then
System.LogAlways("[System] Restoring serverdata from file 'backup.lua'");
--source:close();
Backup = {};
Script.LoadScript(Root().."Mods/Infinity/System/Read/backup.lua");
if not Backup or #Backup < 1 then
System.LogAlways("[System] Error restoring serverdata from file 'backup.lua'");
end
end
end
Thanks all :).
Edit:
Although the file is now written to the disk fine, the system fails to read the dumped file.
So, now the problem is that the "LoadScript" function isn't doing what you expect:
Because I'm psychic, i have divined that you're writing a Crysis plugin, and are attempting to use it's LoadScript API call.
(Please don't assume everyone here would guess this, or be bothered to look for it. It's vital information that must form part of your questions)
The script you're writing attempts to set Backup - but your script, as written - does not separate lines with newline characters. As the first line is a comment, the entire script will be ignored.
Basicallty the script you've written looks like this, which is all treated as a comment.
--[[ comment ]]--Backup="Hello!"
You need to write a "\n" after the comment (and, I'd recommend in other places too) to make it like this. In fact, you don't really need block comments at all.
-- comment
Backup="Hello!"
I read a text file to get some info from it and later on I need to rename the directory that the file sits in. I am not able do to that because the file is locked. If I comment out the function that reads from the file or if I manually unlock the file (unlocker utility) everything goes fine.
I am on ruby 1.8.7 (2010-08-16 patchlevel 302) [i386-mingw32]
This line leaves the file open File.open(file).readlines.each{|line|
These two lines leave the file open
my_file=File.open(file,"r")
my_file.collect {|line|
unless I close the file at the end using my_file.close
The man for core 1.8.7 of IO.html#method-c-open states
If the optional code block is given, it will be passed io as an argument, and the IO object will automatically be closed when the block terminates.
So I don't understand why the file is still open.
What would be the one line code in 1.8.7 to read a text file and close it automatically?
The documentation is clear. However, you're passing the block to collect. And since you're not passing it to open, you are responsible for closing the file.
To have file auto-closed, try this:
File.open(file,"r") do |f|
f.collect # or whatever
end
Try passing the block directly to the "open" call:
File.open(file, 'r') do |f|
f.each_line do |line|
# Process each line
end
end
Or if you just want the file contents in a single shot then try this:
lines = File.read(file).split(/\r?\n/)
If you want the block to close the file automagically without passing the file handle to a block, you can use the IO#readlines method of your File object.
array_of_lines = File.readlines('/tmp/foo')
This will read the entire contents of the file, then close the file handle. It's a good option whenever a file is small enough to fit easily into memory.