hisat2-inspect extracts information from a HISAT2 index about what kind of index it is and what reference sequences were used to build it. When run without any options, the tool will output a FASTA file containing the sequences of the original references (with all non-A/C/G/T characters converted to Ns). It can also be used to extract just the reference sequence names using the -n/--names option or a more verbose summary using the -s/--summary option.
hisat2-inspect [options]* <ht2_base>
Note: By default, the tool prints FASTA records of the indexed nucleotide sequences to standard output.