currently reading Learn To Program. Im at page 91-92 where you create a program that moves images from your USB drive to desired location and changing the name of each image. But i get the follwing error when runing the program. Using Ubuntu as you can tell, but get "Invalid cross-device link". Any ideas of how to solve this?
pierre#ubuntu:~/ruby$ ruby move.rb
What would you like to call this batch?
IMG
Downloading 1 files: .move.rb:36:in `rename': Invalid cross-device link - (/media/SanDisk Cruzer Blade/pictures/UMG.jpg, IMG01.jpg) (Errno::EXDEV)
from move.rb:36:in `block in <main>'
from move.rb:17:in `each'
from move.rb:17:in `<main>'
This is the code
# Heres where the pictures are stored
Dir.chdir '/home/pierre/Skrivbord'
# First we find all of the pictures to be moved
pic_names = Dir['/media/SanDisk Cruzer Blade/pictures/**/*.{JPG,jpg}']
puts 'What would you like to call this batch?'
batch_name = gets.chomp
puts
print "Downloading #{pic_names.length} files: "
# This will be our counter. We'll start at 1 today,
# though normally I like to count from 0.
pic_number = 1
pic_names.each do |name|
print '.' # This is our "progress bar".
new_name = if pic_number < 10
"#{batch_name}0#{pic_number}.jpg"
else
"#{batch_name}#{pic_number}.jpg"
end
# This renames the picture, but since "name" has a big long
# path on it, and "new_name" doesn't, it also moves the file to the current
# working directory, which is now Katy's PictureInbox folder. Since it's a
# *move*, this effectively downloads and deletes the originals. And since this
# is a memory card, not a hard drive, each of these takes a second or so; hence,
# the little dots let her know that my program didn't hose her machine.
# (Some marriage advice from your favourite author/programmer: it's all about
# the little things.)
# Now where were we? Oh, yeah...
File.rename name, new_name
# Finally, we increment the counter.
pic_number = pic_number + 1
end
puts # This is so we aren't on progress bar line.
puts 'Done, cutie!'
.. you are trying to use "rename" to physically move a file, and the system is objecting
to this misconception. File.rename can only rename files, it cannot
move them. It works only on one storage device/volume/whatever.
require 'fileutils'
include FileUtils
cp(old, new )
rm (old)
http://www.ruby-forum.com/topic/78627
Related
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')
Here is my code:
filename = ARGV.first
puts "We're gong to erase #{filename}"
puts "If you don't want that, hit CTRL-C (^C)."
puts "If you do want that, hit RETURN."
$stdin.gets
puts "Opening the file..."
target = open(filename, 'w')
puts "Truncating the file. Goodbye!"
target.truncate(0)
puts "Now I'm going to ask you for three lines."
print "line 1: "
line1 = $stdin.gets.chomp
print "line 2: "
line2 = $stdin.gets.chomp
print "line 3: "
line3 = $stdin.gets.chomp
puts "I'm going to write these to the file."
target.write(line1)
target.write("\n")
target.write(line2)
target.write("\n")
target.write(line3)
target.write("\n")
print target.read
puts "And finally, we close it."
target.close
I'm trying to get it to write and then read. It works if I do target.close and then target = open(filename) again at the bottom of the script. Is there another way?
I saw this post about python explaining you need to close a file after writing to it. Does this same thing apply to Ruby? Do I need to use flush?
Also should I be using parentheses after read and close? The example does not.
There's two ways to approach this. You can, as you've done, open the file for writing, write to it, close the file, and reopen it for reading. This is fine. Closing the file will flush it to disk and reopening it will put you back at the beginning of the file.
Alternatively you can open a file for both reading and writing and manually move around within the file, like a cursor in an editor. The options to do this are defined in IO.new.
The problem with your code is this.
target.write("\n")
print target.read
At this point you've been writing to the file. The target file pointer is pointing at the end of the file, like a cursor in an editor. When you target.read it's going to read the end of the file, so you get nothing. You'd have to go back to the beginning of the file first with rewind.
target.write("\n")
target.rewind
print target.read
You'll also have to open the file for reading and writing. w+ can do that, and truncate the file for you.
puts "Opening the file..."
target = File.open(filename, 'w+')
This is an advanced technique most often useful for when you want to hold a lock on a file during the whole reading and writing process to make sure nobody else can work on the file while you are. Generally you do this when you're reading and then writing. For example, if you had a counter in a file you want to read and then increment and make sure nobody can write between.
def read_and_update_counter
value = 0
# Open for reading and writing, create the file if it doesn't exist
File.open("counter", File::RDWR|File::CREAT, 0644) {|f|
# Get an exclusive lock to prevent anyone else from using the
# file while we're updating it (as long as they also try to flock)
f.flock(File::LOCK_EX)
# read the value
value = f.read.to_i
# go back to the beginning of the file
f.rewind
# Increment and write the new value
f.write("#{value + 1}\n")
# Flush the changes to the file out of the in-memory IO cache
# and to disk.
f.flush
# Get rid of any other garbage that might be at the end of the file
f.truncate(f.pos)
}
# File.open automatically closes the file for us
return value
end
3.times { puts read_and_update_counter }
So, I've been working on a Ruby script that blocks reddit during my school hours (useful stuff). Here's the code:
require 'fileutils'
puts "-----------------------------------"
puts "Welcome to the hosts file modifier!"
puts "-----------------------------------"
puts "Option A: Use modified hosts"
puts "Option B: Use original hosts"
puts "Option C: Do nothing"
puts "Please enter your choice: "
input = gets.chomp.downcase
t = Time.now
# Time.now is used is conjunction with function 'original', in option 'b'
def modified
# This function copies the modified (redditblocking) hosts file from Documents to /etc
puts "Moving original hosts file out of /etc"
FileUtils.mv('/etc/hosts', '/Users/(usernameobscured)/Documents/OriginalHosts/hosts')
puts "Done. Now copying modified hosts to /etc"
FileUtils.cp('/Users/(usernameobscured)/Documents/ModifiedHosts/hosts', '/etc/hosts')
puts "Done"
end
def original
# This function deletes the modified hosts file from /etc (since we have a copy in Documents)
# and then moves the original hosts file back to /etc
puts "Deleting modified hosts file from /etc"
FileUtils.rm_rf('etc/hosts')
puts "Done. Now copying original hosts to /etc"
FileUtils.mv('/Users/(usernameobscured)/Documents/OriginalHosts/hosts', '/etc/hosts')
puts "Done"
end
def nothing
# This does... nothing. Literally.
puts "Doing nothing"
end
if input == 'a'
modified
end
if input == 'b'
# Here's when using Time.now becomes helpful: if the hour of the day is less than 5PM,
# then the original hosts file can't be moved back (don't wanna be on reddit during school hours!)
if t.hour > 17
original
elsif t.hour < 17
puts "Too early to use original hosts file. Come back at 5PM"
end
end
if input == 'c'
# Nothing...
nothing
end
As you can see, it moves a modified hosts file from my Documents folder to /etc. The problem I'm having though, as per OS X/Unix security measures, is that I have to run the script via sudo or logged in as root. This is a minor nuisance, however, it's one that I believe can be fixed within the code. How can I get superuser privileges, OR write access to /etc temporarily, via my ruby script, so that I can simply run the script without sudo/root?
Per Unix security model, it is not possible to gain root access without some sort of external intervention (setuid set to the executable, running as root user). Otherwise we would have a gaping security hole.
I am not clear what is exactly your issue of using sudo or rvmsudo or against setting the script setuid (it is possible to configure sudo to not require password for narrowly defined set of commands).
I would just suggest making the various versions of host files group writable by a group that you are member of.
According to this site : http://ruby.about.com/od/rubyversionmanager/qt/Rvm-And-Sudo.htm
you can start executing the script using the rvmsudo command. In your terminal window or shell script:
rvmsudo ruby blockreddit.rb
New to Ruby, probably something silly
Trying to make a directory in order to store files in it. Here's my code to do so
def generateParsedEmailFile
apath = File.expand_path($textFile)
filepath = Pathname.new(apath + '/' + #subject + ' ' + #date)
if filepath.exist?
filepath = Pathname.new(filepath+ '.1')
end
directory = Dir.mkdir (filepath)
Dir.chdir directory
emailText = File.new("emailtext.txt", "w+")
emailText.write(self.generateText)
emailText.close
for attachment in #attachments
self.generateAttachment(attachment,directory)
end
end
Here's the error that I get
My-Name-MacBook-2:emails myname$ ruby etext.rb email4.txt
etext.rb:196:in `mkdir': Not a directory - /Users/anthonydreessen/Developer/Ruby/emails/email4.txt/Re: Make it Brief Report Wed 8 May 2013 (Errno::ENOTDIR)
from etext.rb:196:in `generateParsedEmailFile'
from etext.rb:235:in `<main>'
I was able to recreate the error - it looks like email4.txt is a regular file, not a directory, so you can't use it as part of your directory path.
If you switched to mkdir_p and get the same error, perhaps one of the parents named in '/Users/anthonydreessen/Developer/Ruby/emails/email4.txt/Re: Make it Brief Report Wed 8 May 2013' already exists as a regular file and can't be treated like a directory. Probably that last one named email.txt
You've got the right idea, but should be more specific about the files you're opening. Changing the current working directory is really messy as it changes it across the entire process and could screw up other parts of your application.
require 'fileutils'
def generate_parsed_email_file(text_file)
path = File.expand_path("#{#subject} #{date}", text_file)
while (File.exist?(path))
path.sub!(/(\.\d+)?$/) do |m|
".#{m[1].to_i + 1}"
end
end
directory = File.dirname(path)
unless (File.exist?(directory))
FileUtils.mkdir_p(directory)
end
File.open(path, "w+") do |email|
emailText.write(self.generateText)
end
#attachments.each do |attachment|
self.generateAttachment(attachment, directory)
end
end
I've taken the liberty of making this example significantly more Ruby-like:
Using mixed-case names in methods is highly irregular, and global variables are frowned on.
It's extremely rare to see for used, each is much more flexible.
The File.open method yields to a block if the file could be opened, and closes automatically when the block is done.
The ".1" part has been extended to keep looping until it finds an un-used name.
FileUtils is employed to makes sure the complete path is created.
The global variable has been converted to an argument.
I've been staring at this for hours, but am not sure what i'm doing wrong. I'm trying to write a simple script to move 100 or so files from various locations in an external list. Should be simple enough, and when I run the command through irb, everything works for that one file, but when running the script I get an error. Here's my script.
#! /opt/local/bin/ruby
require 'fileutils.rb'
list_of_files = File.read "files_to_copy.txt"
source_dir = "/Volumes/data/moved_from_share/"
dest_dir = "/Volumes/data/testeroooo/"
list_of_files.each do |line|
copy_from = source_dir + line
copy_to = dest_dir + line
puts copy_from
puts copy_to
puts
FileUtils.cp_r(copy_from, copy_to)
end
Here is some example input from "files_to_copy.txt":
Accounting HG/Accounts Payable/2011/2011_06/ebi_Inv_218876.pdf
Accounting HG/Accounts Payable/2011/2011_06/expeditors_1050006142.tif
Accounting HG/Accounts Payable/2011/2011_06/expeditors_7050627938.tif
And lastly, here is my output with error:
/Volumes/data/moved_from_share/Accounting PG/Accounts Payable/2011/2011_07/
/Volumes/data/testeroooo/Accounting PG/Accounts Payable/2011/2011_07/
/System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/fileutils.rb:1255:in `copy': unknown file type: /Volumes/data/moved_from_share/Accounting PG/Accounts Payable/2011/2011_07/ (RuntimeError)
from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/fileutils.rb:451:in `copy_entry'
from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/fileutils.rb:1324:in `traverse'
from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/fileutils.rb:448:in `copy_entry'
from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/fileutils.rb:423:in `cp_r'
from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/fileutils.rb:1395:in `fu_each_src_dest'
from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/fileutils.rb:1411:in `fu_each_src_dest0'
from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/fileutils.rb:1393:in `fu_each_src_dest'
from /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/lib/ruby/1.8/fileutils.rb:422:in `cp_r'
from copy_it.rb:14
from copy_it.rb:8:in `each'
from copy_it.rb:8
If you have any suggestions, I would love to hear them! Thank you!
Your file list likely contains Accounting PG/Accounts Payable/2011/2011_07/ as an entry, which is a Directory, not a File. This should work perfectly fine, as you're using cp_r.
You could override it to only copy files (assuming your file list includes the subfolder items too):
if File.file?(copy_from)
FileUtils.cp_r(copy_from, copy_to)
end