open(XFIL,"var.txt") || die $!; @main = ; close(XFIL); open(XFIL,">var.txt") || die $!; foreach $line (@main) { $line =~ s/\n/replace/g; print XFIL $line; } close(XFIL); open(XFIL,"var.txt") || die $!; @main = ; close(XFIL); open(XFIL,">var.txt") || die $!; foreach $line (@main) { $line =~ s/the line to be replaced/this is the new line/; $line =~ s/replace/\n/g; print XFIL $line; } close(XFIL);