shl(1)                         DG/UX 5.4R3.00                         shl(1)


NAME
       shl - shell layer manager

SYNOPSIS
       shl

DESCRIPTION
       Shl lets a user interact with more than one shell from a single
       terminal.  The user controls these shells, known as layers, using the
       commands described below.

       The current layer can receive input from the keyboard.  Other layers
       trying to read from the keyboard are blocked.  Output from multiple
       layers is multiplexed onto the terminal.  To block the output of a
       layer when it is not current, set the stty option loblk within the
       layer.

       The stty character swtch (set to ^Z if NUL) switches control to shl
       from a layer.  Shl has its own prompt, >>>, to help distinguish it
       from a layer.

       A layer is a shell that has been bound to a virtual tty device
       (/dev/ttyp??).  The virtual device can be manipulated like a real tty
       device using stty(1) and ioctl(2).  Each layer has its own process
       group id.

   Definitions
       A name is a sequence of characters delimited by a blank, tab or new-
       line.  Only the first eight characters are significant.  The names
       (1) through (7) cannot be used when creating a layer.  They are used
       by shl when no name is supplied.  They may be abbreviated to just the
       digit.

   Commands
       You can issue the following commands from the shl prompt level.  Any
       unique prefix is accepted.

       create [ name ]
              Create a layer called name and make it the current layer.  If
              no argument is given, a layer will be created with a name of
              the form (#) where # is a digit (1,2...7) bound to the layer.
              The shell prompt variable PS1 is set to the name of the layer
              followed by a space.  A maximum of seven layers can be
              created.
       block name [ name ... ]
              For each name, block the output of the corresponding layer
              when it is not the current layer.  This is equivalent to
              setting the stty option loblk within the layer.
       delete name [ name ... ]
              For each name, delete the corresponding layer.  All processes
              in the process group of the layer are sent the SIGHUP signal
              (see signal(2)).
       help (or ?)
              Print the syntax of the shl commands.



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shl(1)                         DG/UX 5.4R3.00                         shl(1)


       layers [ -l ] [ name ... ]
              For each name, list the layer name and its process group.  The
              -l option produces a ps(1)-like listing.  If no arguments are
              given, information is presented for all existing layers.
       resume [ name ]
              Make the layer referenced by name the current layer.  If no
              argument is given, the last existing current layer will be
              resumed.
       toggle Resume the layer that was current before the last current
              layer.
       unblock name  [ name ... ]
              For each name, do not block the output of the corresponding
              layer when it is not the current layer.  This is equivalent to
              setting the stty option loblk within the layer.
       quit   Exit shl.  All layers are sent the SIGHUP signal.
       name   Make the layer referenced by name the current layer.

   Using shl with the C Shell
       If you are using the csh(1), which by default uses Ctrl-Z as the
       suspend character, and you want to reset the switch character for
       shl, you can create an alias such as the following:

       alias shl 'stty old; stty swtch \^g; stty line 1; /usr/bin/shl'

   International Features
       shells managed with shl provide the same functionality with
       characters from supplementary code sets as the current shell.

       Layer names must be specified using ASCII characters only.

FILES
       /dev/ttyp??    Virtual tty devices
       $SHELL         Variable containing pathname of the shell to use
                      (default is /bin/sh).

SEE ALSO
       sh(1), stty(1).
       ioctl(2), signal(2)
       pty(7)

NOTES
       If you are using shl from an xterm window (TERM=xterm), then shl will
       not be able to pass window size information down to each layer.  This
       may cause problems when using utilities such as vi(1) and more(1). To
       resolve this, execute the resize(1) command in each layer.












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