shl(1)                                                               shl(1)




 NAME    [Toc]    [Back]
      shl - shell layer manager

 SYNOPSIS    [Toc]    [Back]
      shl

 DESCRIPTION    [Toc]    [Back]
      shl provides a means for interacting with more than one shell from a
      single terminal by using shell layers.  A layer is a shell that is
      bound to a virtual device.  The virtual device can be manipulated like
      an actual terminal by using stty and ioctl() (see stty(1) and
      ioctl(2)).  Each layer has its own process group ID.  The user
      controls these layers by using the commands described below.

      The current layer is the layer that can receive input from the
      keyboard.  Other layers attempting 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, the
      stty option loblk can be set within the layer.

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

    Definitions    [Toc]    [Back]
      A name is a sequence of characters delimited by a space, tab, or newline
 character.  Only the first eight characters are significant.
      When provided as an argument to the create or name commands, name
      cannot be of the form n or (n), where n is a decimal number.

    Commands    [Toc]    [Back]
      The following commands can be issued from the shl prompt level.  Any
      unique prefix is accepted.

      create [-[name] | name [command]]
                     Create a layer called name and make it the current
                     layer.  If no argument is given, a layer is created
                     with a name of the form (n), where n is the number of
                     the next available slot in an internal table.  Future
                     references to this layer can be made with or without
                     the parentheses.  If name is followed by a command,
                     that command is executed in the layer instead of a
                     shell.  If - is the first argument, a ``login shell''
                     is created in the layer.  The shell prompt variable PS1
                     is set to the name of the layer followed by a space.

      name [oldname] newname
                     Rename the layer oldname, calling it newname.  If
                     oldname is not specified, the current layer name is
                     changed.




 Hewlett-Packard Company            - 1 -   HP-UX 11i Version 2: August 2003






 shl(1)                                                               shl(1)




      ! [command]    Invoke a sub-shell and execute command.  If no command
                     is given, a shell is executed according to the SHELL
                     environment variable.

      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 sttyloblk option 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(5)).

      help (or ?)    Print the syntax of the shl commands.

      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]  Change the status of the layer referred to by name to
                     that of current layer.  If no argument is given, the
                     last existing current layer is changed.

      toggle         Change the status of the previous current layer to that
                     of 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-loblk option
                     within the layer.

      quit           Exit shl.  All layers are sent the SIGHUP signal.

      name           Change the status of the layer referred to by name to
                     that of current layer.  Any unique prefix is accepted.

 WARNINGS    [Toc]    [Back]
    Commands
      The behavior of the block and unblock shl commands is not guaranteed
      when the SHELL environment variable is set to /usr/bin/csh (for
      csh(1)) or /usr/bin/ksh (for ksh(1)), or when the shell saves and
      restores the tty state (defined in termio(7)) before and after each
      command is invoked interactively from that shell.  For both
      /usr/bin/csh and /usr/bin/ksh, the loblk or -loblk options of stty can
      be used from within the layer to block or unblock the output of that
      layer.



 Hewlett-Packard Company            - 2 -   HP-UX 11i Version 2: August 2003






 shl(1)                                                               shl(1)




    Ptydaemon    [Toc]    [Back]
      For shl to function properly, the ptydaemon process must be running on
      the system.  If your system has been installed with the Desktop HP-UX
      product, then ptydaemon will not be started by default. In order to
      start this daemon, change PTYDAEMON_START from a "0" to a "1" in the
      /etc/rc.config.d/ptydaemon file.  The system must either be rebooted
      for this change to take effect, or you can manually start this daemon
      by typing :

           /usr/sbin/ptydaemon

      Note that ptydaemon will also be disabled if the
      DesktopConfig.LITECONFIG fileset has been installed on the system, or
      if the system administrator has previously run the SAM utility and
      selected the Apply Lite HP-UX Configuration Action from within any of
      SAM's Kernel Configuration screens.

 FILES    [Toc]    [Back]
      $SHELL         Variable containing path name of the shell to use
                     (default is /usr/bin/sh).

 SEE ALSO    [Toc]    [Back]
      sh(1), stty(1), ioctl(2), signal(5).

 STANDARDS CONFORMANCE    [Toc]    [Back]
      shl: SVID2, SVID3, XPG2


 Hewlett-Packard Company            - 3 -   HP-UX 11i Version 2: August 2003