OS Module

Command	Description
`os.access('file', mode)` mode: os.F_OK: found os.R_OK: readable os.W_OK: writable os.X_OK: executable	returns True or false based on mode, 'file' means full path to specific file
`os.chdir('path')`	change current working directory to path
`os.chmod('file', mode)` mode: `stat.S_ISUID`: Set user ID on execution `stat.S_ISGID`: Set group ID on execution `stat.S_ENFMT`: Enforced record locking `stat.S_ISVTX`: After execution, save text image `stat.S_IREAD`: Read by owner `stat.S_IWRITE`: Write by owner `stat.S_IEXEC`: Execute by owner `stat.S_IRWXU`: Read, write, and execute by owner `stat.S_IRUSR`: Read by owner `stat.S_IWUSR`: Write by owner `stat.S_IXUSR`: Execute by owner `stat.S_IRWXG`: Read, write, and execute by group `stat.S_IRGRP`: Read by group `stat.S_IWGRP`: Write by group `stat.S_IXGRP`: Execute by group `stat.S_IRWXO`: Read, write, and execute by others `stat.S_IROTH`: Read by others `stat.S_IWOTH`: Write by others `stat.S_IXOTH`: Execute by others	Alter the mode of the file, multiple modes can be applied by using 'or'
`os.chown('file', uid, gid)` `# os.chown('ab.txt', 100, -1)`	change ownership of file, use -1 to leave it unchanged uid: numeric user ID gid: numeric group ID
`os.chroot(path)`	change root directory (UNIX)
`d_fd = os.dup(fd)`	create duplicate file descriptor
`os.environ`	Returns all environment variables. Use os.environ([“HOME”]) like to get specific one.
`os.getenv(key, default=none)`	Return the value of the environment variable key if it exists, or default if it doesn’t.
`os.get_exec_path(env=none)`	Returns the list of dirs that will be searched for a named executable (like ‘bin’ folder)
`os.getlogin()`	Returns the name of user logged in.
`os.getpid()`	Returns current process id
`os.getcwd()`	returns current working directory
`os.isatty(fd)`	returns true if fd is open and is connected to a tty(-like) device, else returns flase
`os.listdir(path)`	returns list of all items present in path
`os.lseek(fd, pos, how)` how: `os.SEEK_SET` or 0: pos relative to the beginning of file `os.SEEK_CUR` or 1: current position `os.SEEK_END` or 2: end of the file	Set current position of fd to pos, modified by how
`os.major(device)` `os.minor(device)`	takes a raw device number, and returns the device major, minor number (usually the x.st_dev or x.st_rdev field from x=os.stat('file'))
`os.makedirs(path, mode)` `#os.makedirs('tmp/a/b/c', 0755)`	like mkdir() (make directory), but here to make c it can also create a and b if not exists
`os.putenv(key, value)`	Set new environment variables
`os.remove(file)`	remove a file. if path is given instead of file, OSError will be raised
`os.removedirs(path)`	remove all directories given in path
`os.rename(src, dst)`	rename src to dst, if dst already exists, it raises OSError
`os.rmdir(path)`	remove a directory
`os.stat(path/file)`	gives following info about the file or path st_mode: protection bits st_ino: inode number st_dev: device st_nlink: number of hard links st_uid: user id of owner st_gid: group id of owner st_size: size of file, in bytes st_atime: time of most recent access st_mtime: time of most recent content modification st_ctime: time of most recent metadata change.
`os.symlink(src, dst)`	create symbolic link of src folder by name dst. just like desktop shortcut but its for directories not files
`os.tmpfile()`	temporary file object. deletes itself when no descriptor
`os.uname()`	Returns system-dependent version information
`os.unsetenv(key)`	Delete the environment variable named key
`os.umask(mask)`	Set current numeric umask and return previous umask
`os.walk(top[, topdown=True, onerror=None, followlinks=False)` `top:` Each directory rooted at directory `topdown:` If topdown is True, or not specified, it scans directories top-down. `onerror:` This may show an error to continue with the walk, or may raise an exception to abort the walk. `followlinks:` This will visit directories that symlinks points to, that is, if set to true.	returns a generator, Every time the generator is called it will follow each directory recursively until no further sub-directories are available from the initial directory that walk was called upon. It Returns: 1. Generated directory path 2. Directories in current generated directory 3. Files in current generated directory
`os.path.` 1. `join('path1', 'path2')` 2. `basename(path)` 3. `dirname(path)` 4. `split(path)` 5. `exists('path')` 6. `isdir()` 7. `isfile()` 8. `splitext('path')`	1. Returns joined paths 2. returns base name 3. directory name 4. ['dir', 'file_name'] 5. True /False 6. True / False 7. True /False 8. ['path/file_name', 'file_extension']