actually, in the php file, $foo="ID_106", its a string which has to be used in the system command. Example:

$foo="ID_106";
system("perl split.pl $foo");
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now, the $foo variable is passed to the perl program. the variable $foo is used for system command in perl. example:

$bar=$ARGV[0]; (the argument input, so now $bar="ID_106")
$var=system("grep -A 1 $bar *.txt");
print $var;
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Over here, $var doesnt work :(