11/3/71                                               ARCHIVE (V)





NAME            archive (library) file format



SYNOPSIS        --



DESCRIPTION     The archive command ar is used to combine several

                files into one.  Its use has three benefits: when

                files are combined, the file space consumed by

                the breakage at the end of each file (256 bytes

                on the average) is saved; directories are smaller

                and less confusing; archive files of object pro-

                grams may be searched as libraries by the loader

                ld.



                A file produced by ar has a "magic number" at the

                start, followed by the constituent files, each

                preceded by a file header.  The magic number is

                -147(10), or 177555(8) (it was chosen to be un-

                likely to occur anywhere else).  The header of

                each file is 16 bytes long:



                  0-7

                     file name, null padded on the right



                  8-11

                     Modification time of the file



                  12

                     User ID of file owner



                  13

                     file mode



                  14-15

                     file size



                If the file is an odd number of bytes long, it is

                padded with a null byte, but the size in the

                header is correct.



                Notice there is no provision for empty areas in

                an archive file.



FILES           --



SEE ALSO        ar, ld



DIAGNOSTICS     --



BUGS            --



OWNER           ken, dmr