xNightR00T File Manager

#! /bin/bash
#
# Test ability to connect to remote direct socket (JetDirect) server.
#
# Exits:   0 port on host accepts data
#          1 host $1 not set
#          2 no connection possible to port on host
#          4 connection possible to port on host but does not accept data
# The program head is in the coreutils RPM and therefore assumed to exist.
#
# Johannes Meixner <jsmeix@suse.de> 2002, 2007, 2008, 2009, 2010, 2011, 2014
# Jiri Srain <jsrain@suse.cz>, 2002
# $Id: test_remote_socket 43943 2008-01-28 13:38:58Z mzugec $

#set -x

# Make sure to have a clean environment:
export PATH="/sbin:/usr/sbin:/usr/bin:/bin"
export LC_ALL="POSIX"
export LANG="POSIX"
umask 022
# Disable bash file name globbing:
set -f

MY_NAME=${0##*/}
HOST="$1"
[ -z "$HOST" ] && { echo -en "\nUsage:\n$MY_NAME HOST [PORT]\n" 1>&2 ; exit 1 ; }
PORT="$2"
[ -z "$PORT" ] && PORT=9100

# Test whether connection is possible to port on host:
# If the test fails, show an error message and exit with non-zero exit code.
# The outermost subshell avoids job control messages like "[1] job_pid" and "[1]+ Done..." or "[1]+ Terminated...".
# The hardcoded 2 seconds timeout is waited in any case so that the test needs always basically that timeout time.
# In POSIX shells wait returns the exit code of the job even if it had already terminated when wait was started,
# see http://pubs.opengroup.org/onlinepubs/9699919799/utilities/wait.html that reads:
# "This volume of POSIX.1-2008 requires the implementation to keep the status
#  of terminated jobs available until the status is requested":
if ( ( echo -n '' >/dev/tcp/$HOST/$PORT ) & ECHO_PID=$! ; sleep 2s ; kill $ECHO_PID &>/dev/null ; wait $ECHO_PID )
then # Test whether port on host accepts data:
     if ( ( echo -en '\r' >/dev/tcp/$HOST/$PORT ) & ECHO_PID=$! ; sleep 2s ; kill $ECHO_PID &>/dev/null ; wait $ECHO_PID )
     then echo -en "\nPort '$PORT' on host '$HOST' accepts data\n"
          exit 0
     fi
     echo -en "\nConnection possible to port '$PORT' on host '$HOST' but does not accept data\n"
     exit 4
fi

# The test failed:
echo -en "\nNo connection possible to port '$PORT' on host '$HOST'."
echo -en "\n(Network issue or wrong host or wrong port or firewall active there?)\n\n"
exit 2