*   added `_out` and `_out_bufsize` validator [#346](amoffat/sh#346)
*   bugfix for internal stdout thread running when it shouldn't [#346](amoffat/sh#346)

*   regression bugfix on timeout [#344](amoffat/sh#344)
*   regression bugfix on `_ok_code=None`

*   further improvements on cpu usage

*   regression in cpu usage [#339](amoffat/sh#339)

*   fd leak regression and fix for flawed fd leak detection test [#337](amoffat/sh#337)

*   support for `io.StringIO` in python2

*   added support for using raw file descriptors for `_in`, `_out`, and `_err`
*   removed `.close()`ing `_out` handler if FIFO detected

*   composed commands no longer propagate `_bg`
*   better support for using `sys.stdin` and `sys.stdout` for `_in` and `_out`
*   bugfix where `which()` would not stop searching at the first valid executable found in PATH
*   added `_long_prefix` for programs whose long arguments start with something other than `--` [#278](amoffat/sh#278)
*   added `_log_msg` for advanced configuration of log message [#311](amoffat/sh#311)
*   added `sh.contrib.sudo`
*   added `_arg_preprocess` for advanced command wrapping
*   alter callable `_in` arguments to signify completion with falsy chunk
*   bugfix where pipes passed into `_out` or `_err` were not flushed on process end [#252](amoffat/sh#252)
*   deprecated `with sh.args(**kwargs)` in favor of `sh2 = sh(**kwargs)`
*   made `sh.pushd` thread safe
*   added `.kill_group()` and `.signal_group()` methods for better process control [#237](amoffat/sh#237)
*   added `new_session` special keyword argument for controlling spawned process session [#266](amoffat/sh#266)
*   bugfix better handling for EINTR on system calls [#292](amoffat/sh#292)
*   bugfix where with-contexts were not threadsafe [#247](amoffat/sh#195)
*   `_uid` new special keyword param for specifying the user id of the process [#133](amoffat/sh#133)
*   bugfix where exceptions were swallowed by processes that weren't waited on [#309](amoffat/sh#309)
*   bugfix where processes that dupd their stdout/stderr to a long running child process would cause sh to hang [#310](amoffat/sh#310)
*   improved logging output [#323](amoffat/sh#323)
*   bugfix for python3+ where binary data was passed into a process's stdin [#325](amoffat/sh#325)
*   Introduced execution contexts which allow baking of common special keyword arguments into all commands [#269](amoffat/sh#269)
*   `Command` and `which` now can take an optional `paths` parameter which specifies the search paths [#226](amoffat/sh#226)
*   `_preexec_fn` option for executing a function after the child process forks but before it execs [#260](amoffat/sh#260)
*   `_fg` reintroduced, with limited functionality.  hurrah! [#92](amoffat/sh#92)
*   bugfix where a command would block if passed a fd for stdin that wasn't yet ready to read [#253](amoffat/sh#253)
*   `_long_sep` can now take `None` which splits the long form arguments into individual arguments [#258](amoffat/sh#258)
*   making `_piped` perform "direct" piping by default (linking fds together).  this fixes memory problems [#270](amoffat/sh#270)
*   bugfix where calling `next()` on an iterable process that has raised `StopIteration`, hangs [#273](amoffat/sh#273)
*   `sh.cd` called with no arguments no changes into the user's home directory, like native `cd` [#275](amoffat/sh#275)
*   `sh.glob` removed entirely.  the rationale is correctness over hand-holding. [#279](amoffat/sh#279)
*   added `_truncate_exc`, defaulting to `True`, which tells our exceptions to truncate output.
*   bugfix for exceptions whose messages contained unicode
*   `_done` callback no longer assumes you want your command put in the background.
*   `_done` callback is now called asynchronously in a separate thread.
*   `_done` callback is called regardless of exception, which is necessary in order to release held resources, for example a process pool