if ( ( $file =~ m/^CHECK*/ ) && ( $file =~ m/.txt$/ ) ) {
print "name is = $file\n";
}

##</code><code>##

CHECK_CH.ABC12_A1.txt
CHECK_CH.ABC12.txt

##</code><code>##

CHECK_CH.ABC12_A1.txt
CHECK_CH.ABC12.txt

##</code><code>##

CHECK_CH.ABC12.txt