dfits and fitsort - anjavdl/PHY517_AST443 GitHub Wiki
dfits and fitsort are command-line programs to read the headers of FITS files. They are installed on the analysis machine(s) in the Astro Computing Lab. For a local installation, they can be downloaded here.
To view the header of a single FITS file:
dfits image1.fits
To read a specific keyword (in this case, EXPTIME) from a single FITS file:
dfits image1.fits | fitsort EXPTIME
To read one or more specific keywords from a list of FITS files:
dfits image*.fits | fitsort EXPTIME IMAGETYP