CGI (shell script) not write in the file with echo command

Question

I'm having problems to write in the file with my CGI.

I make a simple HTML formular to press a button and write a phrase in the .txt file, but it doesn't work.

The server is an Apache2.

The scrips works if executed in the terminal.

ps. The final line of CGI works, updating a HTML page URL.

file index.html

<html>
<title>BeagleBone</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://www.w3schools.com/w3css/4/w3.css">
<body>

<div class="w3-container w3-green">
  <h1>BeagleBone GPIO Control</h1> 
  <p>Acesso remoto a GPIO's em rede local</p> 
</div>

<div class="w3-row-padding">
  <div class="w3-third">
    <h2>GPIO x</h2>
    <p>Led blue</p>
    <form method="POST" action="/cgi-bin/led.cgi">
  <input type="submit" name="led" value="ON">
  <input type="submit" name="led" value="OFF">
</form>
  </div>

</body>
</html>

file led.gci

#!/bin/bash

LED_FILE="/home/gpcosta/Desktop/data.txt"

read CONTENT

if [ "$CONTENT" == "led=ON" ]; then
    echo "Apertou botao ON" >> $LED_FILE
elif [ "$CONTENT" == "led=OFF" ]; then
    echo "Apertou botao OFF" >> $LED_FILE
fi

echo "Content-type: text/html"
echo ""
echo '<html>'
echo '<meta http-equiv="refresh" CONTENT="0;url=http://192.168.15.20/index.html">'
echo '</html>'

The cgi permissions below

enter image description here

Stupid question, is your ScriptAlias directive configured with your /usr/lib/cgi-bin directory ? — Andre Gelinas
– Andre Gelinas, Commented Oct 17, 2018 at 11:49
Hi, Andre! Is my directive is configured to /usr/lib/cgi-bin. The cgi files is found and executed, but echo cmd not works. Thanks about your reply! — Gustavo Costa
– Gustavo Costa, Commented Oct 17, 2018 at 11:54
Then, what about the permission on the data.txt file ? Apache runs typically with a user that should not have write access to most of the files, especially in your home directory, even if you started it with root. — Andre Gelinas
– Andre Gelinas, Commented Oct 17, 2018 at 11:57
It seems to me the mostly likely reason for your problem is that neither if/else block is being accessed, because the value of "$CONTENT" is not what you think it is. Add printf "CONTENT=${CONTENT}XXX\n" before the if` tests to be sure you CONTENT is as expected. Good luck. — shellter
– shellter, Commented Oct 17, 2018 at 15:44
Or, since it's a cgi script, comment out the meta tag (which should be in a HEAD tag) and do echo "<body><pre>$CONTENT</pre></body>" — glenn jackman
– glenn jackman, Commented Oct 17, 2018 at 15:55

mmendescortes · Accepted Answer · 2020-07-05 21:54:09Z

1

It's because the web server don't have permissions on the directory.

To solve this, run the following script on your cgi server:

echo “content-type: text/html”
echo “”
echo “<html>
        <head>
                <meta charset='utf-8'/>
                <title>What permission?</title>
        </head>
        <body>
                <p>Run this on your server terminal:</p>
                <pre>chown $(whoami) ${PWD}
chmod 755 ${PWD}</pre>
  </body>
</html>”

Then simply copy the script your web browser will display and paste it on the CGI Server terminal, remember to run it with a priviledged user.

edited Jul 5, 2020 at 21:54

answered Jul 1, 2020 at 0:21

mmendescortes

1291 silver badge6 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

CGI (shell script) not write in the file with echo command

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related