Executing a BASH Linux Script calling from HTTP

Question

I'm new to HTML, and I was able to print a simple linux date command on the web browser by calling the below script. However I'm trying to display the contents of the variable v on the web-browser and I cannot do it. What am I doing wrong? The batch file works fine when I run it from command line, in other words there were no errors.

#!/bin/bash
echo "Content-type: text/html"
echo ""
echo "<html>"
echo "<head>"
echo "Today is $(date)"

v=`ssh -t -q jcrm16 ". ~/.profile;/opt/reuters/scripts/matt/adsuserlist"`
printf "$v"
# echo $(printf "$v")     << tried this did not work
echo "</body>"
echo "</html>"

Using bash like this is a very bad idea - people can pass environment variables (IFS!), all sorts of nasty stuff.. Hearthbleed too. It's a bad practice to use bash as a CGI language. — synthesizerpatel
– synthesizerpatel, Commented Dec 23, 2014 at 22:01
I'm assuming your question is more academic than for practical purposes. There are a lot of languages out there that are far better suited (and vetted for the same security issues that @synthesizerpatel pointed out) to producing dynamic HTML. However, I've provided a pointer to at least give you an idea of what is wrong with the markup you are outputting. — Jason M. Batchelor
– Jason M. Batchelor, Commented Dec 23, 2014 at 22:03
Thanks Jason. I plan to use perl & CGI formats . For now I just need to do this simple display. — matthewthegreat
– matthewthegreat, Commented Dec 23, 2014 at 22:08
Unless your server is set up to allow bash as an executable format from your HTTPD, however, you're not going to get very far. I would suggest you look at just going into perl directly, rather than trying to work with bash. — Jason M. Batchelor
– Jason M. Batchelor, Commented Dec 23, 2014 at 22:16

janos · Accepted Answer · 2014-12-23 22:16:48Z

1

Instead of putting the output of an ssh command in a variable and then displaying the value of that variable, it would be better to just let the output of ssh be displayed directly:

#!/bin/bash

cat <<EOF
Content-type: text/html

<html>
<head></head>
<body>
Today is $(date)
EOF

ssh -t -q jcrm16 ". ~/.profile;/opt/reuters/scripts/matt/adsuserlist"

echo "</body>"
echo "</html>"

But that doesn't change the fact that using ssh is a terrible terrible idea and you shouldn't do it.

In any case, your original script should work. Most probably it doesn't work because the ssh itself doesn't work when used by your web server process. Either way, use something else for your testing, not ssh.

answered Dec 23, 2014 at 22:16

janos

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3 Comments

Jason M. Batchelor Over a year ago

The html markup is still broken in this example, however. Need to close that <head> tag and open a <body> tag for it to be considered valid HTML.

matthewthegreat Over a year ago

Hi. Thx for suggestions. I redirected the output of shh to text file and then tries to print it , cat it etc .. I used other awk command. the problem I'm having now is that the display data look continuous text without a line break, so not sure what to do next.

janos Over a year ago

@matthewthegreat next: maybe ask a new question with specific details of your new problem

Jason M. Batchelor · Accepted Answer · 2014-12-23 22:01:38Z

0

You need to close your <head> block, and open your <body> block, as such:

#!/bin/bash
echo "Content-type: text/html"
echo ""
echo "<html>"
echo "<head></head>"
echo "<body>"
echo "Today is $(date)"

v=`ssh -t -q jcrm16 ". ~/.profile;/opt/reuters/scripts/matt/adsuserlist"`
printf "$v"
# echo $(printf "$v")     << tried this did not work
echo "</body>"
echo "</html>"

answered Dec 23, 2014 at 22:01

Jason M. Batchelor

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3 Comments

matthewthegreat Over a year ago

thanks I did the modifications as u suggested and still no go? Basically the only thing showing up on html page is the content of the $(date).

Jason M. Batchelor Over a year ago

Oh, wait a sec... printf is a print-format command, right? You need to follow the format of printf... right now, you're not doing anything but providing an invalid template for text to be formatted into. See the help here: wiki.bash-hackers.org/commands/builtin/printf

matthewthegreat Over a year ago

Ok So I redirected the output of the command to a file test.txt. I was able to use CAT command or do a for i loop to can and display the file. The problem is that when it gets displayed on the webpage; it all comes out as a continuous text without a line break.

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