Extract aligned bases for each read from a large mapping data set

Hi

I have a large mapping dataset (about 170 million of reads in the alignment (sam file). I also have the input data (fasta.gz and fastq.gz files) I want to know how to efficiently extract next items using a single script from the sam file. I know samtools stats get some of them, however I would like to have one single script.

• Total reads
• Total bases
• total aligned reads
• total aligned bases
• total bases per read
• aligned bases per read

Thanks for any help