How to execute and display output from command cgi script

Question

I want to execute command from variable and display the output. code look like this but it doesn't work I don't know exactly why?

#!/bin/sh

echo "Content-type: text/html"
echo

argu="arp -a | grep $REMOTE_ADDR | awk '{print $4}'"

echo '<html> <head> <title> CGI script </title> </head> <body>'
echo "<h1>HELLO $REMOTE_ADDR</h1>"
echo "Mac is ${argu}"

You should include the output you get, and show what part is incorrect. — bright-star
– bright-star, Commented Feb 26, 2017 at 1:02

l'L'l · Accepted Answer · 2017-02-26 00:51:26Z

1

Your script has a few issues, mainly the argu command should run in a sub-shell:

#!/bin/sh

echo "Content-type: text/html"
echo

argu="$(arp -a | grep "$REMOTE_ADDR" | awk '{print $4}')"

echo '<html> <head> <title> CGI script </title> </head> <body>'
echo "<h1>HELLO $REMOTE_ADDR</h1>"
echo "Mac is $argu"

In addition, the variable you grep should be double-quoted. You can always check the syntax of scripts such as this @ shellcheck.net.

answered Feb 26, 2017 at 0:51

l'L'l

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1 Comment

xhutpl Over a year ago

It still doesn't work sir. Can't get the mac address

Gerhard · Accepted Answer · 2017-02-26 02:10:52Z

0

It will work if you set argu like this:

argu=`arp -a | grep "$REMOTE_ADDR" | awk '{print $4}'`

The reasons:

Command substitution can be done with `command`
$4 must not be enclosed by double quotation marks, otherwise it will be substituted by the shell instead of awk.

Make sure $REMOTE_ADDR is set.

answered Feb 26, 2017 at 2:10

Gerhard

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