Pseudo-terminal

i5/OS™ PASE supports both AT&T and Berkeley Software Distributions (BSD) style devices. From a programming perspective, these devices work in i5/OS PASE in the same way that they work on AIX^®.

i5/OS PASE allows a maximum of 1024 instances for AT&T style devices, and a maximum of 592 BSD style devices. When the system is started, the first 32 instances of each device type are created automatically.

Configure PTY devices in i5/OS PASE

On AIX, an administrator uses smit to configure the number of available devices of each type. In i5/OS PASE, these devices are configured in the following way:

For AT&T-style devices, i5/OS PASE supports autoconfiguration. If the first 32 instances are in use and an application tries to open another instance, the CHRSF device is created in the integrated file system automatically, up to the limit of 1024 devices.

For BSD-style devices, you must create the CHRSF devices manually, using the i5/OS PASE mknod utility. To do this, you need to know the major numbers for the BSD subordinate and BSD primary devices as well as the naming convention. The following example shell script shows how to create additional BSD pseudo-terminal (PTY) devices. It creates them in groups of 16.

Note: By using the code examples, you agree to the terms of the Code license and disclaimer information.

#!/QOpenSys/usr/bin/ksh

prefix="pqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
bsd_tty_major=32949
bsd_pty_major=32948

if [ $# -lt 1 ]
then
    echo "usage: $(basename $0) ptyN "
    exit 10
fi

function mkdev {
  if [ ! -e $1 ] 
  then 
    mknod $1 c $2 $3
    chown QSYS $1
    chmod 0666 $1
  fi
}

while [ "$1" ]
do
  N=${1##pty}
  if [ "$N" = "$1" -o "$N" = "" -o $N -lt 0 -o $N -gt 36 ]
  then
      echo "skipping: \"$1\": not valid, must be in the form ptyN where: 0 <= N <= 36"
      shift
      continue
  fi

  minor=$((N * 16))
  pre=$(expr "$prefix" : ".\{$N\}\(.\)")

  echo "creating /dev/[pt]ty${pre}0 - /dev/[pt]ty${pre}f"
  for i in 0 1 2 3 4 5 6 7 8 9 a b c d e f
  do
    echo ".\c"
    mkdev /dev/pty${pre}${i} $bsd_pty_major $minor
    echo ".\c"
    mkdev /dev/tty${pre}${i} $bsd_tty_major $minor
    minor=$((minor + 1))
  done
  echo ""

  shift
done

For more information about PTY devices, see the AIX documentation Web site.