cons - Console multiplexer

cons - Console multiplexer#

cons is the interactive console multiplexer for the L4Re operating system. It allows to multiplex console output and input from and to different clients such as VMs and L4Re components and programs.

cons is an interactive command line tool that works with commands and key shortcuts:

cons>
cons> help
            cat - Dump buffer of channel
          clear - Clear screen
        connect - Connect to channel
           drop - Drop kept client
           grep - Search for text
           help - Help screen
           hide - Hide channel output
        hideall - Hide all channels output
           info - Info screen
           keep - Keep client from garbage collection
            key - Set key shortcut for channel
           list - List channels
           show - Show channel output
        showall - Show all channels output
           tail - Show last lines of output
      timestamp - Prefix log with timestamp

Key shortcuts when connected:
   Ctrl-E .      - Disconnect
   Ctrl-E e      - Inject Ctrl-E
   Ctrl-E c      - Inject Ctrl-C
   Ctrl-E z      - Inject Ctrl-Z
   Ctrl-E q      - Inject ESC
   Ctrl-E l      - Inject Break sequence

Global key shortcuts:
   Ctrl-E h      - Hide all output (except current)
   Ctrl-E s      - Show all output

User defined key shortcuts:
   Ctrl-E 1     - Connect to console 'vm1'
cons>

Probably the most important command is the connect command with which you can connect to a client such as a VM:

cons> connect vm1
~ #
~ #
~ # uname
Linux
~ #

Leave a console with Ctrl-E ..

The list command understands globbing, like this:

cons> list vm*
           vm1 (1) [        ] out:  360/ 18828 in:    0/   21
cons>

Shortcuts#

There can only be key shortcuts for accessing specific consoles. In our example console vm1 has the key shortcut 1 such that the console of VM1 can be accessed quickly by typing Ctrl-E 1.

The connect command has the short command c.

The list command has the short command ls.

Multiplexers and Frontends#

cons is able to connect multiple clients with multiple in/output servers.

Clients are handled by a multiplexer. Each multiplexer publishes a server capability that allows to create new client connections. The default multiplexer is normally known under the cons capability.

Actual in/output is handled by separate frontends. From the point-of-view of cons, a frontend consists of an IPC channel to a server that speaks an appropriate server protocol. By default the L4.Env.log capability is used.

For clients, cons implements the L4::Vcon and the Virtio console interface. The supported frontends are limited to L4::Vcon only.

Command-line Options#

Please refer to the doxygen documentation.

Contents