AR(5)                                BSD                                 AR(5)



NAME
     ar - archive (library) file format

SYNOPSIS
     #include <ar.h>

DESCRIPTION
     The archive command ar combines several files into one.  Archives are
     used mainly as libraries to be searched by the link-editor ld.

     A file produced by ar has a magic string at the start, followed by the
     constituent files, each preceded by a file header.  The magic number and
     header layout as described in the include file are:

          #define ARMAG  "!<arch>\n"
          #define SARMAG 8

          #define ARFMAG "`\n"

          struct ar_hdr {
                  char   ar_name[16];
                  char   ar_date[12];
                  char   ar_uid[6];
                  char   ar_gid[6];
                  char   ar_mode[8];
                  char   ar_size[10];
                  char   ar_fmag[2];
          };

     The name is a blank-padded string.  The ar_fmag field contains ARFMAG to
     help verify the presence of a header.  The other fields are left-
     adjusted, blank-padded numbers.  They are decimal except for ar_mode,
     which is octal.  The date is the modification date of the file at the
     time of its insertion into the archive.

     Each file begins on a even (0 mod 2) boundary; a newline is inserted
     between files if necessary.  Nevertheless the size given reflects the
     actual size of the file exclusive of padding.

     There is no provision for empty areas in an archive file.

     The encoding of the header is portable across machines.  If an archive
     contains printable files, the archive itself is printable.

SEE ALSO
     ar(1), ld(1), nm(1)

BUGS
     File names lose trailing blanks.  Most software dealing with archives
     takes even an included blank as a name terminator.