def main_init():
    """Parse command line arguments and start main script for analysis."""
    parser = ArgumentParser(prog="PLIP", description=descript)
    pdbstructure = parser.add_mutually_exclusive_group(required=True)  # Needs either PDB ID or file
    # '-' as file name reads from stdin
    pdbstructure.add_argument("-f", "--file", dest="input", nargs="+", help="Set input file, '-' reads from stdin")
    pdbstructure.add_argument("-i", "--input", dest="pdbid", nargs="+")
    outputgroup = parser.add_mutually_exclusive_group(required=False)  # Needs either outpath or stdout
    outputgroup.add_argument("-o", "--out", dest="outpath", default="./")
    outputgroup.add_argument("-O", "--stdout", dest="stdout", action="store_true", default=False, help="Write to stdout instead of file")
    parser.add_argument("--rawstring", dest="use_raw_string", default=False, action="store_true", help="Use Python raw strings for stdout and stdin")
    parser.add_argument("-v", "--verbose", dest="verbose", default=False, help="Set verbose mode", action="store_true")
    parser.add_argument("-p", "--pics", dest="pics", default=False, help="Additional pictures", action="store_true")
    parser.add_argument("-x", "--xml", dest="xml", default=False, help="Generate report file in XML format",
                        action="store_true")
    parser.add_argument("-t", "--txt", dest="txt", default=False, help="Generate report file in TXT (RST) format",
                        action="store_true")
    parser.add_argument("-y", "--pymol", dest="pymol", default=False, help="Additional PyMOL session files",
                        action="store_true")
    parser.add_argument("--maxthreads", dest="maxthreads", default=multiprocessing.cpu_count(),
                        help="Set maximum number of main threads (number of binding sites processed simultaneously)."
                             "If not set, PLIP uses all available CPUs if possible.",
                        type=int)
    parser.add_argument("--breakcomposite", dest="breakcomposite", default=False,
                        help="Don't combine ligand fragments with covalent bonds but treat them as single ligands for the analysis.",
                        action="store_true")
    parser.add_argument("--altlocation", dest="altlocation", default=False,
                        help="Also consider alternate locations for atoms (e.g. alternate conformations).",
                        action="store_true")
    parser.add_argument("--debug", dest="debug", default=False,
                        help="Turn on DEBUG mode with extended log.",
                        action="store_true")
    parser.add_argument("--nofix", dest="nofix", default=False,
                        help="Turns off fixing of PDB files.",
                        action="store_true")
    parser.add_argument("--nofixfile", dest="nofixfile", default=False,
                        help="Turns off writing files for fixed PDB files.",
                        action="store_true")
    parser.add_argument("--nopdbcanmap", dest="nopdbcanmap", default=False,
                        help="Turns off calculation of mapping between canonical and PDB atom order for ligands.",
                        action="store_true")
    parser.add_argument("--dnareceptor", dest="dnareceptor", default=False,
                        help="Uses the DNA instead of the protein as a receptor for interactions.",
                        action="store_true")
    parser.add_argument("--name", dest="outputfilename", default="report",
                        help="Set a filename for the report TXT and XML files. Will only work when processing single structures.")
    ligandtype = parser.add_mutually_exclusive_group()  # Either peptide/inter or intra mode
    ligandtype.add_argument("--peptides", "--inter", dest="peptides", default=[],
                        help="Allows to define one or multiple chains as peptide ligands or to detect inter-chain contacts",
                        nargs="+")
    ligandtype.add_argument("--intra", dest="intra", help="Allows to define one chain to analyze intra-chain contacts.")
    parser.add_argument("--keepmod", dest="keepmod", default=False,
                        help="Keep modified residues as ligands",
                        action="store_true")
    # Optional threshold arguments, not shown in help
    thr = namedtuple('threshold', 'name type')
    thresholds = [thr(name='aromatic_planarity', type='angle'),
                  thr(name='hydroph_dist_max', type='distance'), thr(name='hbond_dist_max', type='distance'),
                  thr(name='hbond_don_angle_min', type='angle'), thr(name='pistack_dist_max', type='distance'),
                  thr(name='pistack_ang_dev', type='other'), thr(name='pistack_offset_max', type='distance'),
                  thr(name='pication_dist_max', type='distance'), thr(name='saltbridge_dist_max', type='distance'),
                  thr(name='halogen_dist_max', type='distance'), thr(name='halogen_acc_angle', type='angle'),
                  thr(name='halogen_don_angle', type='angle'), thr(name='halogen_angle_dev', type='other'),
                  thr(name='water_bridge_mindist', type='distance'), thr(name='water_bridge_maxdist', type='distance'),
                  thr(name='water_bridge_omega_min', type='angle'), thr(name='water_bridge_omega_max', type='angle'),
                  thr(name='water_bridge_theta_min', type='angle')]
    for t in thresholds:
        parser.add_argument('--%s' % t.name, dest=t.name, type=lambda val: threshold_limiter(parser, val),
                            help=argparse.SUPPRESS)

    arguments = parser.parse_args()
    config.VERBOSE = True if (arguments.verbose or arguments.debug) else False
    config.DEBUG = True if arguments.debug else False
    config.MAXTHREADS = arguments.maxthreads
    config.XML = arguments.xml
    config.TXT = arguments.txt
    config.PICS = arguments.pics
    config.PYMOL = arguments.pymol
    config.STDOUT = arguments.stdout
    config.RAWSTRING = arguments.use_raw_string
    config.OUTPATH = arguments.outpath
    config.OUTPATH = tilde_expansion("".join([config.OUTPATH, '/'])
                                     if not config.OUTPATH.endswith('/') else config.OUTPATH)
    config.BASEPATH = config.OUTPATH  # Used for batch processing
    config.BREAKCOMPOSITE = arguments.breakcomposite
    config.ALTLOC = arguments.altlocation
    config.PEPTIDES = arguments.peptides
    config.INTRA = arguments.intra
    config.NOFIX = arguments.nofix
    config.NOFIXFILE = arguments.nofixfile
    config.NOPDBCANMAP = arguments.nopdbcanmap
    config.KEEPMOD = arguments.keepmod
    config.DNARECEPTOR = arguments.dnareceptor
    config.OUTPUTFILENAME = arguments.outputfilename
    # Make sure we have pymol with --pics and --pymol
    if config.PICS or config.PYMOL:
        try:
            import pymol
        except ImportError:
            write_message("PyMOL is required for --pics and --pymol.\n", mtype='error')
            raise
    # Assign values to global thresholds
    for t in thresholds:
        tvalue = getattr(arguments, t.name)
        if tvalue is not None:
            if t.type == 'angle' and not 0 < tvalue < 180:  # Check value for angle thresholds
                parser.error("Threshold for angles need to have values within 0 and 180.")
            if t.type == 'distance':
                if tvalue > 10:  # Check value for angle thresholds
                    parser.error("Threshold for distances must not be larger than 10 Angstrom.")
                elif tvalue > config.BS_DIST + 1:  # Dynamically adapt the search space for binding site residues
                    config.BS_DIST = tvalue + 1
            setattr(config, t.name.upper(), tvalue)
    # Check additional conditions for interdependent thresholds
    if not config.HALOGEN_ACC_ANGLE > config.HALOGEN_ANGLE_DEV:
        parser.error("The halogen acceptor angle has to be larger than the halogen angle deviation.")
    if not config.HALOGEN_DON_ANGLE > config.HALOGEN_ANGLE_DEV:
        parser.error("The halogen donor angle has to be larger than the halogen angle deviation.")
    if not config.WATER_BRIDGE_MINDIST < config.WATER_BRIDGE_MAXDIST:
        parser.error("The water bridge minimum distance has to be smaller than the water bridge maximum distance.")
    if not config.WATER_BRIDGE_OMEGA_MIN < config.WATER_BRIDGE_OMEGA_MAX:
        parser.error("The water bridge omega minimum angle has to be smaller than the water bridge omega maximum angle")
    expanded_path = tilde_expansion(arguments.input) if arguments.input is not None else None
    main(expanded_path, arguments.pdbid)
Parse command line arguments and start main script for analysis.