How to detect key press in cgi shell script?

Shell Programming and Scripting
1

I want to detect key pressed in my .cgi web page, but it does not work even I found the code in other web site.

My code is :

#!/bin/sh

#=================================================
#    PATH defination
# ================================================
DEFAULT_CONFIG=/etc/default_path
. ${DEFAULT_CONFIG}

if [ -r   $MAIN_CONFIG ]; then
        . $MAIN_CONFIG
else 
        echo "$MAIN_CONFIG not found !!!"
        exit 1
fi
#=================================================
#    Get external script function
# ================================================
#getData()
#
#    parameters:        $1 : variable name
#                        $2    : the filename to be get from
#
#    Return variable name: "getDataRtn" - return request of $1 value
#
#   i.e.    getData "LAN1_IFACE" $MAIN_CONFIG
#            answer=$getDataRtn
# 
if [ -r   ${WWW_SCRIPTS_LIB_PATH}/getData.sh ]; then
        . ${WWW_SCRIPTS_LIB_PATH}/getData.sh
else 
        echo "${WWW_SCRIPTS_LIB_PATH}/getData() not found !!!"
        exit 1
fi

#=================================================
#    Get display language
# ================================================
getData "LANGUAGE=" $MAIN_CONFIG
Language=$getDataRtn
    . ${WWW_MSG_PATH}/${Language}/DCapture
    . ${WWW_MSG_PATH}/${Language}/commsg
    
#=================================================
#    Main
# ================================================
echo "Content-type: text/html"
echo "Pragma: no-cache"
echo ""
echo "<HTML><HEAD>"
echo "<meta http-equiv=content-type content=text/html; charset=UTF-8>"
echo "<TITLE>$msg010</TITLE>"
. ${WWW_SCRIPTS_LIB_PATH}/style-init.sh
echo "</HEAD>"
echo "<BODY>"
ShowSubLogo "$msg010"

if [ "$CONTENT_LENGTH" != "" ]; then
    #if [ "$Stop" != "" ]; then
        killall tcpdump
        #ShowEndSucess "Capture Done!" "DCf_form"
    #fi    
fi
read -s -n 1 -p "Press any key to continue..."
echo "Test"
echo "<br> </br>"
echo "<br> </br>"
echo "<form name=DbC_form method=post action=DCapturefile.cgi>"
echo "<input name=Start value=\"$msg020\" type=submit>"
echo "<br> </br>"
echo "</form>"
echo "</BODY></HTML>"

The red word is what I found, but the result in the web page running is print Test,
that means: it skip the read operation?

So, is there has another way to detect pressing key down?

My purpose is :

Press any key to execute the shell script.

The whole process is:

Press "Start" button, and transfer to another .cgi web page.
The web page is do the shell script :

/fs1/tcpdump/tcpdump -c 20000 -s 1500 -w $filename &

and it works fine.
But I want to do another shell script when user want to stop capture tcpdump.
So, all the resolution I think are:

  1. Detect key pressing, and if key pressed, do killall tcpdump.
    2.There is a button in the .cgi web(html code), click button, and execute the shell script: killall tcpdump .

But I do not know how to press a button to do shell script as well.

Or is there has the other way?

Any help appreciated.

2

CGI scripts run under HTTP and as such you cannot interact with them as you do with a standard script.

You could send a Javascript function to the client (web browser) that detected a key press and made a new request (HTTPRequestObject) to a separate script which returned the second part of your page, this response could then be set as the innerHTML of a div on the already loaded page.

1 Like
3

Thanks! I will try again.