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  • tclconfig
  • tests
  • aclocal.m4
  • configure
  • pty.c


A Tcl package to handle pseudo TTYs.

Package Usage

To open a pseudo TTY use the pty::open command which will return the master channel and the name of the slave device file such as /dev/pts/3:

package require pty

lassign [pty::open] masterChan slaveName
puts "Slave device file name: $slaveName"
set slaveChan [open $slaveName r+]

puts $masterChan "message from master"
flush $masterChan
puts "Received at slave: \"[gets $slaveChan]\""

puts $slaveChan "message from slave"
flush $slaveChan
puts "Received at master: \"[gets $masterChan]\""

close $slaveChan
close $masterChan

Exported Commands

pty::open ?-option?
Opens a pseudo TTY master slave pair and returns the pair as a list with the first element being the master channel and the second being the name of the slave device file. There is a single option:

Prevents grantpt() from being run to change the mode and ownership of the slave pseudo-terminal device.


  • A C/C++ compiler (Currently tested with gcc and g++)
  • Tcl 8.5+ and development files

Compiling and Installing

pty is designed to be run under Unix and has been most thoroughly tested on Linux.

From the root directory of the repository, the directory this file is in, create the Makefiles:

$ configure ...

Then compile the project:

$ make

To install the package to a sensible location run the following as root. Make a note of the directories installed to in case of problems; these locations locations are also recorded in install_manifest.txt:

$ make install


There is a test suite in tests/. To run it:

$ tclsh tests/pty.test.tcl


If you find after installing that the package can't be found when package require is called, then add part of the installation path to the environmental variable TCLLIBPATH. For bash you could put the following in your .bashrc:

export TCLLIBPATH="$TCLLIBPATH /usr/local/lib"

Alternatively you could copy the files for the package (pkgIndex.tcl and to a directory such as pty-tcl0.1/ off of one of the directories in Tcl's auto_path variable. To find the directories in the auto_path from the command line:

$ echo "puts \$auto_path" | tclsh


If you want to improve this package make a pull request to the repo on github. Please put any pull requests in a separate branch to ease integration and add a test to prove that it works.


Copyright (C) 2015, Lawrence Woodman

This software is licensed under an MIT Licence. Please see the file,, for details.