empty

NAME

SYNOPSIS

DESCRIPTION

There are several common forms of command lines for empty. But the first execution of empty is usually a start in the daemon mode to fork a new command (process) under PTY-session. This can be done with -f key. An interface for the input and output data channels of the forked process is performed by two fifo files which names must be specified with -i and -o keys. This files are automaticaly created/deleted any time you start/exit empty daemon so you must not create them manually.

At this point any application can easily communicate with forked process by writing data to the input fifo and reading answers from the output fifo, see EXAMPLES section for the details. To simplify this operations, empty offers abilities to just send any data (use -s key), or even to watch the output fifo for the keyphrase and reply to the input fifo with response (see -w key).

Note! Input fifo for empty -f ... is usually an output fifo for empty -w and empty -s forms. And output fifo of empty -f ... is an input fifo for empty -w ...

If something goes wrong the forked process may be killed by the standard kill command, or using -k key of empty.

The following options are available:

-f

fork, spawn, start or execute a new process specified by the command and its arguments.

-s

send data to the forked process.

-w

watch for the keyphrase and if specified send the response to the input fifo. If response is not set, empty waits for the proper keyphrase in the output fifo and exits with zero code.

-k pid

send signal to the process with pid. If signal is omitted SIGTERM is used.

-i fifo1

a fifo file, which is used as input for a forked process.

-o fifo2

a fifo file, which is used as output for a forked process.

-t n

Use with -w key. Wait for maximum of n seconds (default is 10) to receive the keyphrase. If keyphrase was not recognised, empty exits with -1 code.

-n

remove ending "newline" character when sending data.

-v

kvazi verbose mode. Show all contents of received buffer.

EXAMPLES

Start a new PTY-session with telnet to localhost:

        empty -f -i in.fifo -o out.fifo telnet localhost

Interact with telnet:

        empty -w -i out.fifo -o in.fifo ogin my_user
        empty -w -i out.fifo -o in.fifo assword my_password

Send commands to telnet with empty:

        empty -s -o in.fifo who
        empty -s -o in.fifo "ls -la /"

Just cat output from telnet:

        cat out.fifo

Send commands to telnet with echo:

        echo "who am i" > in.fifo
        echo "uname -a" > in.fifo

Kill a process with PID 1234:

        empty -k 1234
or
        kill 1234

RETURN VALUES

AUTHOR

Index

NAME

SYNOPSIS

DESCRIPTION

EXAMPLES

RETURN VALUES

AUTHOR