Recursively copy dst must always be a directory src may be either a dir or a file.

CopyFile copies contents of src to dst atomically using SharedReadWriteMask as permissions.

CopyFileWithPerms copies the contents from src to dst atomically.

Dir sets working directory for the child process.

ExecL executes the specified command and outputs its Stdout/Stderr into the specified writer `out`.

ExecL executes the specified command and outputs its Stdout/Stderr into the specified writer `out`, using `logger` for logging.

ExecWithInput executes the specified command and outputs its Stdout/Stderr into the specified writer `out`.

RemoveAll removes the specified directory including sub-directories.

SetEnv passes specified environment variables to the child process.

CommandOptionSetter defines an interface to configure child process before execution.