How to Find the Most Recently Modified Folder in a Directory Using Ruby

How can you find the most recently modified folder in a directory using Ruby?

Dir.glob("a_directory/*/").max_by {|f| File.mtime(f)}

Dir.glob("a_directory/*/") returns all the directory names in a_directory (as strings) and max_by returns the name of the directory for which File.mtime returns the greatest (i.e. most recent) date.

Edit: updated answer to match the updated question

Ruby: Finding most recently modified file

Dir.glob("*").max_by {|f| File.mtime(f)}

How can I get the path for the last created file in a directory using Ruby?

I think this is fairly brief:

Dir.glob(File.join(path, '*.*')).max { |a,b| File.ctime(a) <=> File.ctime(b) }

How to get last modified file in a directory to pass to system commands using Ruby?

There's no need to shell out to ls and parse its output at all. Ruby gives you standard library methods to fetch directory contents and examine file mtimes. Here's a ruby method to return the name of a file in a directory with the latest mtime.

def last_modified_in dir
  Dir.glob( File.join( dir,'*' ) ).
  select  {|f| File.file? f }.
  sort_by {|f| File.mtime f }.
  last
end

irb> system 'mkdir -p /tmp/foo'
irb> system 'rm /tmp/foo/*'
irb> ('a'..'c').each { |f| system "touch /tmp/foo/#{f}"; sleep 1; }
irb> puts last_modified_in '/tmp/foo'
# => /tmp/foo/c

Ruby - Get the second most recent file from a directory?

You can do as below using Ruby 2.2.0, which added an optional argument to the methods Enumerable#max_by, Enumerable#min_by and Enumerable#min etc.

Dir.glob("./logs/*").max_by(2) {|f| File.mtime(f)}
# gives first 2 maximun.
# If you want the second most recent
Dir.glob("./logs/*").max_by(2) {|f| File.mtime(f)}.last

max_by(n) {|obj| block } → obj

If the n argument is given, minimum n elements are returned as an array.

How to find most recently modified file in a remote directory (via ssh)?

This is less a Net::SSH question as it is "What command can I issue to find the most recently modified file?"

SSH connections can issue a command, so once you know what command to send, or execute, you're done. I'd look at:

ls -Alt path/to/files | sed -n '2p'

Fleshing out something more usable results in:

require 'net/ssh'

HOST = 'hostname.domain'
USER = 'user'
PASSWORD = "password"

output = Net::SSH.start(HOST, USER, :password => PASSWORD) { |ssh|
  ssh.exec!('ls -alt . | grep pattern_to_find') 
}

puts output

Which, after filling in the fields with the right values and running it, connected to one of my hosts at work and returned something like:

drwxr-xr-x  11 xxxxxxxxxxxx xxxxxxxxx    4096 Oct  2 16:20 development

If you have multiple hits you need to retrieve, either expand the pattern after grep or discard the pipe to grep and parse your resulting output in Ruby once the command returns. You can also discard the t flag from ls if you want to sort locally, though it's a better idea to offload as much of the processing to the far-side host, rather than have it return a huge glob of data and process it locally. The less you return, the faster your overall code will be.

How to order files by last modified time in ruby?

How about simply:

# If you want 'modified time', oldest first
files_sorted_by_time = Dir['*'].sort_by{ |f| File.mtime(f) }

# If you want 'directory change time' (creation time for Windows)
files_sorted_by_time = Dir['*'].sort_by{ |f| File.ctime(f) }

Getting a list of folders in a directory

Jordan is close, but Dir.entries doesn't return the full path that File.directory? expects. Try this:

 Dir.entries('/your_dir').select {|entry| File.directory? File.join('/your_dir',entry) and !(entry =='.' || entry == '..') }

How to search a folder and all of its subfolders for files of a certain type

You want the Find module. Find.find takes a string containing a path, and will pass the parent path along with the path of each file and sub-directory to an accompanying block. Some example code:

require 'find'

pdf_file_paths = []
Find.find('path/to/search') do |path|
  pdf_file_paths << path if path =~ /.*\.pdf$/
end

That will recursively search a path, and store all file names ending in .pdf in an array.

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