projects / unix-history / blame
| Commit | Line | Data |
|---|---|---|
| 60a17f4e JH |
1 | This is GNU cpio, a program to manage archives of files. |
| 2 | As of version 2.0, it supports the features of the System V release 4 | |
| 3 | cpio, including support for tar archives. | |
| 4 | ||
| 5 | The main advantages of GNU cpio over Unix versions are: | |
| 6 | ||
| 7 | * It can access tape drives on other hosts using TCP/IP. | |
| 8 | ||
| 9 | * `-o' and `-p' can copy symbolic links either as symbolic links or, | |
| 10 | with `-L', as the files they point to. | |
| 11 | ||
| 12 | * `-i' automatically recognizes the archive format and tries to | |
| 13 | recover from corrupted archives. | |
| 14 | ||
| 15 | * The output of '-itv' looks like 'ls -l'. | |
| 16 | ||
| 17 | * It accepts long-named options as well as traditional | |
| 18 | single-character options. | |
| 19 | ||
| 20 | A few features of other versions of cpio are missing from GNU cpio, including: | |
| 21 | ||
| 22 | * The `-6' option to support Sixth Edition Unix cpio archives with `-i'. | |
| 23 | ||
| 24 | * An option to limit volume size, like afio -s. | |
| 25 | ||
| 26 | ||
| 27 | GNU cpio supports the POSIX.1 "ustar" tar format. GNU tar supports a | |
| 28 | somewhat different, early draft of that format. That draft format has | |
| 29 | a slightly different magic number in the tar header and doesn't | |
| 30 | include the path prefix part of the header, which allows storing file | |
| 31 | names that are longer than 100 characters. GNU cpio knows to | |
| 32 | recognize the nonstandard GNU tar "ustar" archives. | |
| 33 | ||
| 34 | The following patch to GNU tar 1.11.1 makes GNU tar recognize standard | |
| 35 | "ustar" archives, such as GNU cpio produces, except that it won't use | |
| 36 | the path prefix. Without this patch, GNU tar thinks that standard | |
| 37 | "ustar" archives are old-format tar archives and can not use the extra | |
| 38 | information that "ustar" format contains. If you use this patch, | |
| 39 | remember that you will lose the beginnings of paths that are longer | |
| 40 | than 100 characters. That's why it's not an official part of GNU tar. | |
| 41 | (Adding support for the path prefix to GNU tar is not trivial.) | |
| 42 | ||
| 43 | --- list.c.orig Mon Sep 14 17:04:03 1992 | |
| 44 | +++ list.c Wed Oct 14 14:02:28 1992 | |
| 45 | @@ -439,7 +439,7 @@ | |
| 46 | st->st_ctime = from_oct(1+12, header->header.ctime); | |
| 47 | } | |
| 48 | ||
| 49 | - if (0==strcmp(header->header.magic, TMAGIC)) { | |
| 50 | + if (0==strncmp(header->header.magic, TMAGIC, 5)) { | |
| 51 | /* Unix Standard tar archive */ | |
| 52 | *stdp = 1; | |
| 53 | if (wantug) { | |
| 54 | ||
| 55 | Mail suggestions and bug reports for GNU cpio to | |
| 56 | bug-gnu-utils@prep.ai.mit.edu. |