• Remove the newline.
• Escape anything special to the shell.
• Don't use the shell to do something Perl can do trivially.
• Do it all in the shell. (date >> log.txt)

i had been doing this. but the $eng_dat and $hindi_dat never get printed. how do i solve this issue.

#!/bin/env perl
open(HANDLE,"<labels");@lines=<HANDLE>;close HANDLE;
for($i=0;$i<=$#lines;$i++)
    {
    ($english_index,$hindi_index,$nua)=split(/\|/,$lines[$i]);
    @english=split(/:/,$english_index);
    @hindi=split(/:/,$hindi_index);
    print @english,"\n",@hindi,"\n";
    for($j=0;$j<=$#english;$j++)
        {
            $eng_dat=`grep --regexp '$english[$j]' /home/vikash/pro_1/
+en_1000`;
            print $eng_dat;
            
            
        }    
    for($j=0;$j<=$#hindi;$j++)
        {
            $hindi_dat=`grep --regexp '$hindi[$j]'    /home/vikash/pro
+_1/HI_1000`;
            print $hindi_dat;
        }
    print "***********************************************************
+******\n";
    }
[download]

system("echo \'$abc\' >> log.txt");
[download]

Why the backslashes?

Habit. Silly precaution. You're right, they aren't needed in this particular situation.