[RUBY] The permission specification of the FileUtils method is an octal number.

When creating a directory with mkdir_p, I also want to specify the permission ...

About mkdir_p

Create the directory dir and all its parent directories.

For example

require 'fileutils'
Will check all the directories below(If not)Create.


Quote https://docs.ruby-lang.org/ja/latest/class/FileUtils.html#M_MAKEDIRS

Try to create by specifying permission

Linux commands ... mkdir -p -m 755 ./hoge1/hoge2/hoge3/ruby ruby


require 'fileutils'

FileUtils.mkdir_p('./hoge1/hoge2/hoge3/ruby', mode: 755)


Run immediately

$ ruby test.rb
$ ls -la
d-wxrw--wt    3 casix  staff     96 Jun 12 01:06 hoge1/

No, obviously the authority is not 755 ...

I read the source code of mkdir_p


# File fileutils.rb, line 194
def mkdir_p(list, mode: nil, noop: nil, verbose: nil)
  list = fu_list(list)
  fu_output_message "mkdir -p #{mode ? ('-m %03o ' % mode) : ''}#{list.join ' '}" if verbose
  return *list if noop


If you read carefully the processing of the arguments put in mode

mkdir -p #{mode ? ('-m %03o ' % mode) : ''}


#{mode ? ('-m %03o ' % mode) : ''}

Should be 755,

'-m %03o ' % mode

If you put 755 in mode

irb(main):001:0> mode = 755
=> 755
irb(main):002:0> '-m %03o ' % mode
=> "-m 1363 "

1363 is returned

That means ...

FileUtils.mkdir_p('./hoge1/hoge2/hoge3/ruby', mode: 755)
# ↓
# $ mkdir -p -m 1363 ./hoge1/hoge2/hoge3/ruby

That it was

It was an octal number, not a decimal number, that should be included in the argument

'-m %03o ' % mode

# %Since 03o is output as a 0-packed 3-digit octal number
#Mode is a number converted from 755 to decimal.(493)Put in

irb(main):001:0> mode = 0o755
=> 493
irb(main):002:0> '-m %03o ' % mode
=> "-m 755 "

Looks good

Try to fix

FileUtils.mkdir_p('./hoge1/hoge2/hoge3/ruby', mode: 0o755)

# FileUtils.mkdir_p('./hoge1/hoge2/hoge3/ruby', mode: 0755)But k
$ ls -la
drwxr-xr-x    3 casix  staff     96 Jun 12 01:43 hoge1/

It seems that it can be set with 755!

In FileUtils, the permission setting was octal, regardless of mkdir_p

It wasn't limited to mkdir_p in the first place All the methods that can specify permission with FileUtils seem to have the same specifications


(By the way, it's easy to forget the knowledge that when it starts from 0, it becomes an octal number ...)

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