bcftools cat description
Bcftools cat concatenates BCF files. The input files are required to be sorted and have identical samples appearing in the same order.
Parent program: samtools
SAMTools provide various utilities for manipulating alignments in the SAM format, including sorting, merging, indexing and generating alignments in a per-position format. It is very convinient for handling reads mapped to reference genome. Normally SAMtools is used in intermediate step between raw read mapping and SNP or variants callingm, because it allows to effeciently store mapped reads.