<p>In Linux, what is the difference between <code>/dev/ttyS0</code> and <code>/dev/ttys0</code>?</p>

<p>I know that the first is a serial port, but what about the second, with the small <code>s</code>?</p>

[{'answer_id': 22113, 'author': 'Community', 'author_id': -1, 'author_profile': 'https://Stackoverflow.com/users/-1', 'pm_score': 2, 'selected': True, 'text': '<p><a href="http://www.linuxselfhelp.com/HOWTO/Text-Terminal-HOWTO-6.html" rel="nofollow noreferrer">see this</a></p>\n\n<blockquote>\n  <p>For a pseudo terminal pair such as\n  ptyp3 and ttyp3, the pty... is the\n  master or controlling terminal and the\n  tty... is the slave. There are only 16\n  ttyp\'s: ttyp0-ttypf (f is a\n  hexadecimal digit). <strong>To get more\n  pairs, the 3 letters q, r, s may be\n  used instead of p</strong>. For example the\n  pair ttys8, ptys8 is a pseudo terminal\n  pair. The master and slave are really\n  the same "port" but the slave is used\n  by the application program and the\n  master is used by a network program\n  (or the like) which supplies (and\n  gets) data to/from the slave port.</p>\n</blockquote>\n'}, {'answer_id': 22118, 'author': 'Kev', 'author_id': 419, 'author_profile': 'https://Stackoverflow.com/users/419', 'pm_score': 0, 'selected': False, 'text': '<p>And this: <a href="http://lists.opensuse.org/archive/opensuse/2003-12/msg02404.html" rel="nofollow noreferrer">http://lists.opensuse.org/archive/opensuse/2003-12/msg02404.html</a></p>\n'}, {'answer_id': 22124, 'author': 'Espo', 'author_id': 2257, 'author_profile': 'https://Stackoverflow.com/users/2257', 'pm_score': 0, 'selected': False, 'text': "<p>In the Linux devices.txt file in the kernel docs it says:</p>\n\n<pre><code>3 char    Pseudo-TTY slaves\n      0 = /dev/ttyp0    First PTY slave\n      1 = /dev/ttyp1    Second PTY slave\n        ...\n    255 = /dev/ttyef    256th PTY slave\n\n    These are the old-style (BSD) PTY devices; Unix98\n    devices are on major 136 and above.\n</code></pre>\n\n<p>and goes on to say</p>\n\n<pre><code>4 char    TTY devices\n      0 = /dev/tty0     Current virtual console\n\n      1 = /dev/tty1     First virtual console\n        ...\n     63 = /dev/tty63    63rd virtual console\n     64 = /dev/ttyS0    First UART serial port\n        ...\n    255 = /dev/ttyS191  192nd UART serial port\n\n    UART serial ports refer to 8250/16450/16550 series devices.\n\n    Older versions of the Linux kernel used this major\n    number for BSD PTY devices.  As of Linux 2.1.115, this\n    is no longer supported.  Use major numbers 2 and 3.\n</code></pre>\n\n<p>I don't know how much this helps you, but should get you started in the right direction.</p>\n"}]
['https://Stackoverflow.com/questions/22106', 'https://Stackoverflow.com', 'https://Stackoverflow.com/users/1585/']