Hi Monks

I want to execute some programs from a CGI script. After browsing in perlmonks and reading perlsec, I found that I can use the following approach:- 

die "Can't fork: $!" unless defined $pid = open(KID, "-|");
if ($pid) {           # parent
    while (<KID>) {
       # do something
    }
    close KID;
} else {
    exec 'myprog', 'arg1', 'arg2' 
        or die "can't exec myprog: $!";
}

[download]

I have a shell script whose arguments are the path and the executable 

Shell Script:

#!/bin/ksh

# print the arguments for checking
# $1 is the directory 
# $2 is the executable 

echo $1
echo $2

# change dir to $1
cd $1

# execute $2
$2

echo "Exit"

[download]

and I execute that using 'exec' as shown 

...
...

$dir = 'some path'; # untainted
$exe = 'some executable'; # untainted
...
...
exec 'unixscript.sh', $dir, $exe
...
...

[download]

I am wondering if it is a good idea to execute unix shell scripts with some arguments as shown? I want to use this approach in CGI scripts to run executables from the web. ( Note that the 'executable' is preset inside the CGI script and IS NOT an user input.) Are there any security issues with this approach?

In reply to Using exec() for executing shell scripts in CGI by stumbler

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.