Search code examples
linuxgo

os.Mkdir and os.MkdirAll permissions

I'm trying to create a log file at the start of my program.

I need to check if a /log directory exists if it doesn't create the directory then move on to creating the log file.

Well I tried to use os.Mkdir (as well as os.MkdirAll), but no matter what value I put into the second parameter I get a locked out folder with no permissions. What value should this be in order to get a read / write for user folder? I thought it would be 0x700 but it doesn't seem to work.

Thanks!

Solution

  • You can use octal notation directly:

    os.Mkdir("dirname", 0700)

    Permission Bits

    Permission bits are historically given in Octal, so the literal value must be prefixed by a 0. Otherwise it will be interpreted as decimal and give confusing results. This is consistent with the Linux command chmod.

    +-----+---+--------------------------+
| rwx | 7 | Read, write and execute  |
| rw- | 6 | Read, write              |
| r-x | 5 | Read, and execute        |
| r-- | 4 | Read,                    |
| -wx | 3 | Write and execute        |
| -w- | 2 | Write                    |
| --x | 1 | Execute                  |
| --- | 0 | no permissions           |
+------------------------------------+

+------------+------+-------+
| Permission | Octal| Field |
+------------+------+-------+
| rwx------  | 0700 | User  |
| ---rwx---  | 0070 | Group |
| ------rwx  | 0007 | Other |
+------------+------+-------+

    A Unix Permission Primer

    Common Permission Usages

    0755 Commonly used on web servers. The owner can read, write, execute. Everyone else can read and execute but not modify the file.

    0777 Everyone can read write and execute. On a web server, it is not advisable to use ‘777’ permission for your files and folders, as it allows anyone to add malicious code to your server.

    0644 Only the owner can read and write. Everyone else can only read. No one can execute the file.

    0655 Only the owner can read and write, but not execute the file. Everyone else can read and execute, but cannot modify the file.

    www.maketecheasier.com/file-permissions-what-does-chmod-777-means/

    Directory Permissions on Linux

    When applying permissions to directories on Linux, the permission bits have different meanings than on regular files. (source)

    Read bit The user can read the file names contained in the directory.
    Write bit The user can {add,rename,delete} files names IF the execute bit is set too.
    Execute bit The user can enter the directory and access the files inside.

    https://unix.stackexchange.com/a/21252

    Permissions Calculator

    permissions calculator

    A handy permissions calculator.