Merge the given files by sorting them as a group. Each input file should already be individually sorted. If any of the global options Mbdfinr are given but no key fields are specified, sort compares the entire lines according to the global options. The last resort comparison honors the -r global option. If no fields or global options are specified, -s has no effect.
GNU sort has no limits on input line length or restric- silently supplies one.
The following options affect the ordering of output lines. They may be specified globally or as part of a specific key field. Ignore leading blanks when finding sort keys in each line. Invalid names compare low to valid names. Compare according to arithmetic value an initial numeric string consisting of optional white space, an optional - sign, and zero or more digits, optionally followed by a decimal point and zero or more digits.