Please provide more information about the error. For example what kind of file names you have and the directory structure. system may split the argument string to words possibly corrupting argument vector if the file name contains whitespaces. You would be safer using systems LIST argument format. For example,

@count=`find dir_name -name *.tar`;
@args = qw( tar -x -f );

foreach $cnt(@count){
    push @args, $cnt;
    system(@args) == 0 or die "system '@args' failed: $?";
    pop @args;
}
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