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Document a bit pts.

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This commit is contained in:
Olivier Houchard 2006-01-26 01:34:49 +00:00
parent af09c34069
commit 4691674ab4
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=154839
1 changed files with 34 additions and 0 deletions
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34
share/man/man4/pty.4
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@ -177,12 +177,46 @@ mode, command operations may be detected with a
.Xr select 2
for exceptional conditions.
.El
There is currently two pty systems available : the original BSD pty, and a
SysVR4 pts-like implementation.
You can switch between the two implementations by setting the
.Va kern.pts.enable
sysctl. Setting it to 0 will use the BSD pty, to non-zero the pts
implementation. It defaults to 0.
You can set the maximum number of ptys which can be allocated at the same time
with the
.Va kern.pts.max
sysctl. It defaults to 1000.
It is not recommanded to use more than 1000 pseudo-terminals, as all software
which use
.Xr utmp 5
won't be able to handle pseudo-terminals with number superior to 999.
The pts implementation also supports the
.Dv TIOCGPTN
.Xr ioctl 2
call, which takes a pointer to an unsigned int as a parameter and provides the
number of the pty.
.Sh FILES
.Bl -tag -width /dev/tty[p-sP-S][0-9a-v]x -compact
The files used by the BSD pseudo terminals implementation are :
.It Pa /dev/pty[p-sP-S][0-9a-v]
master pseudo terminals
.It Pa /dev/tty[p-sP-S][0-9a-v]
slave pseudo terminals
.El
The files used by the pts implementation are :
.Bl -tag -width /dev/pts/[num]x -compact
.It Pa /dev/ptmx
control device, returns a file descriptor to a new master pseudo terminal
when opened.
.It Pa /dev/pty[num]
master pseudo terminals
.It Pa /dev/pts/[num]
slave pseudo terminals
.El
.Sh DIAGNOSTICS
None.