AFIO

NAME

SYNOPSIS

Frequently used options:
-v -Z -F -K -n
-s volsize -b blocksize -y pattern -Y pattern

DESCRIPTION

With -o, reads pathnames from the standard input and writes an archive.

With -t, reads an archive and writes a table-of-contents to the standard output.

With -i, installs the contents of an archive relative to the working directory.

With -p, reads pathnames from the standard input and copies the files to each directory.

With -r, reads archive and verifies it against the filesystem. This is useful for verifying tape archives.

Creates missing directories as necessary, with permissions to match their parents.

Generates sparse filesystem blocks (with lseek(2)) when possible.

Removes leading slashes from pathnames when reading, writing, and cataloging an archive, unless instructed not to.

Supports multi-volume archives during interactive operation (i.e., when /dev/tty is accessible and SIGINT is not being ignored).

OPTIONS

-a

Preserve the last access times (atimes) of the files read when making or verifying an archive. Warning: if this option is used, afio will change the last inode changed times (ctimes) of these files. Thus, this option cannot be used together with an incremental backup scheme that relies on the ctimes being preserved.

-b size

Read or write size-character archive blocks. Suffices of b, k and m denote multiples of 512, 1024 and 1048576, respectively. Defaults to 5120 for compatibility with cpio(1).

-c count

Buffer count archive blocks between I/O operations. A large count is recommended with streaming magnetic tape drives.

-d

Don't create missing directories.

-e bound

Pad the archive to a multiple of bound characters. Recognizes the same suffices as -s. Defaults to 1x (the -b block size) for compatibility with cpio(1).

-f

Spawn a child process to actually write to the archive; provides a clumsy form of double-buffering. Requires -s for multi-volume archive support.

-g

Change to input file directories. Avoids quadratic filesystem behavior with long similar pathnames. Requires all absolute pathnames, including those for the -o archive and the -p directories.

-h

Follow symbolic links, treating them as ordinary files and directories.

-j

Don't generate sparse filesystem blocks.

-k

Skip corrupt data at the beginning of an archive (rather than complaining about unrecognizable input).

-l

With -o, write file contents with each hard link.

With -t, report hard links.

With -p, attempt to link files rather than copying them.

-m

Mark output files with a common current timestamp (rather than with input file modification times).

-n

Protect newer existing files (comparing file modification times).

-s limit

Restrict each portion of a multi-volume archive to limit characters. Recognizes the same suffices as -b. Also, the suffix x denotes a multiple of the -b block size (and must follow any -b specification). Useful with finite-length devices which do not return short counts at end of media (sigh); output to magnetic tape typically falls into this category. When an archive is being read, using -s causes afio to prompt for the next disk if the specified volume length is reached. The -s will also cause afio to prompt if there is a premature EOF while reading the input. The special case -s 0 will activate this prompting for the next disk on EOF without setting a volume length.

-u

Report files with unseen links.

-v

Verbose. Report pathnames as they are processed. With -t, gives an ls -l style report (including link information).

-w filename

Treats each line in filename as an -y pattern, see -y.

-x

Retain file ownership and setuid/setgid permissions. This is the default for the super-user; he may use -X to override it.

-y pattern

Restrict processing of archive read to names matching shell pattern pattern. Specify once for each pattern to be recognized. Use -Y to supply patterns which are not to be processed. -Y overrides -y if a filename matches both. Unless the -S option is given, leading slashes are ignored when matching patterns, e.g. /etc/passwd matches etc/passwd. See also -w and -W.

-z

Print execution statistics. This is meant for human consumption; use by other programs is officially discouraged.

-A

Do not turn absolute paths into relative paths. That is don't remove the leading slash.

-B

If the -v option is used, prints the byte offset of the start of each file in the archive. If your tape drive can start reading at any position in an archive, the output of -B can be useful for doing quick selective restores.

-D controlscript

Set the control script name to controlscript, see the section on control files below.

-E filename

Read file extensions, separated by whitespace, from filename. Files with these extensions are not to be compressed when using the -Z option. filename may contain comments preceded by a #. If no -E is given, files with the extensions .Z .z .gz .arc .gif .zip .zoo .lha .jpeg .jpg .tpz .taz .tgz and .tzg will not be compressed.

-F

This is a floppy disk, -s is required. Causes floppy writing in O_SYNC mode under Linux. With kernel version 1.1.54 and above, this allows afio to detect some floppy errors while writing. Uses shared memory if compiled in otherwise mallocs as needed (a 3b1 will not be able to malloc the needed memory w/o shared memory), afio assumes either way you can malloc/shmalloc a chunck of memory the size of one disk. Examples: 795k: 3.5" (720k drive), 316k (360k drive)

At the end of each disk this message occurs:
 Ready for disk [#] on [output] 
                       (remove the disk when the light goes out)
 Type "go" (or "GO") when ready to proceed (or "quit" to abort):

-G factor

Specifies the gzip(1) compression speed factor, used when compressing files with the -Z option. Factor 1 is the fastest with least compression, 9 is slowest with best compression. The default value is 6. See also the gzip(1) manual page. If you have a slow machine or a fast backup medium, you may want to specify a low value for factor to speed up the backup. On large (>200k) files, -G 1 typically zips twice as fast as -G 6, while still achieving a better result than compress(1). The zip speed for small files is mainly determined by the invocation time of gzip (1), see the -T option.

-K

Verify the output against what is in the memory copy of the disk (-F required). If the writing or verifying fails the following menu pops up

    [Writing/Verify] of disk [disk #] has FAILED!
        Enter 1 to RETRY this disk
        Enter 2 to REFORMAT this disk before a RETRY

        Enter quit to ABORT this backup

Currently, afio will not process the answers 1 and 2 in the right way. The menu above is only useful in that it signifies that something is wrong.

-L Log_file_path

Specify the name of the file to log errors and the final totals to.

-M size

Specifies the maximum amount of memory to use for the temporary storage of compression results when using the -Z option. The default is -M 2m (2 megabytes). If the compressed version of a file is larger than this (or if afio runs out of virtual memory), gzip(1) is run twice of the file, the first time to determine the length of the result, the second time to get the compressed data itself.

-P progname

Use the program progname instead of the standard gzip for compression and decompression with the -Z option. See also the -Q and -U options.

-Q opt

Pass the option opt to the compression or decompression program used with the -Z option. For passing multiple options, use -Q multiple times. If no -Q flag is present, the standard options are passed. The standard options are -c -6 when the program is called for compression and -c -d when the program is called for decompression. Use the special case -Q "" if no options at all are to be passed to the program.

-R

This is the command that is run when you enter 2 to reformat the disk after a failed verify. The default (fdformat /dev/fd0H1440) can be changed to a given system's default by editing the Makefile. You are also prompted for formatting whenever a disk change is requested.

-S

Do not ignore leading slashes when matching -y and -Y patterns. See also -A.

-T threshold

Only compress a file when using the -Z option if its length is at least threshold. The default is -T 0k. This is useful if you have a slow machine or a fast backup medium. Specifying -T 3k typically halves the number of invocations of gzip(1), saving some 30% computation time, while creating an archive that is only 5% longer. The combination -T 8k -G 1 typically saves 70% computation time and gives a 20% size increase. The latter combination may be a good alternative to not using -Z at all. These figures of course depend heavily on the kind of files in the archive and the processor - i/o speed ratio on your machine.

-U

If used with the -Z option, forces compressed versions to be stored of all files, even if the compressed versions are bigger than the original versions. This is useful when the -P and -Q options are used to replace the compression program gzip with an encryption program in order to make an archive with encrypted files.

-W filename

Treats each line in filename as an -Y pattern, see -y.

-Y pattern

See -y.

-Z

Gzip the files on the way out, in, and passing without links (valid w/ or w/o -F or -K), requires gzip(1) to be in your path.

NOTES

o

Specify - to read or write the standard input or output, respectively. This disables multi-volume archive handling.

o

Prefix a command string to be executed with an exclamation mark (!). The command is executed once for each archive volume, with its standard input or output piped to afio. It is expected to produce a zero exit code when all is well.

o

Use system:file to access an archive in file on system. This is really just a special case of pipelining. It requires a 4.2BSD-style remote shell (rsh(1C)) and a remote copy of afio.

o

Anything else specifies a local file or device. An output file will be created if it does not already exist.

Recognizes obsolete binary cpio(1) archives (including those from machines with reversed byte order), but cannot write them.

Recovers from archive corruption by searching for a valid magic number. This is rather simplistic, but, much like a disassembler, almost always works.

Optimizes pathnames with respect to the current and parent directories. For example, ./src/sh/../misc/afio.c becomes src/misc/afio.c.  

CONTROL FILES

Control file labels. The control file mechanism can be used for many things. Examples are putting archive descriptions at the beginning of the archive and embedding lists of files to move before unpacking the rest or the archive.

To distinguish between different uses, the label of a control file should indicate the program that made the contol file and the purpose of the control file data. It should have the form

   programname.kindofdata

where programname is the name of the backup program that generated the control file, and kindofdata is the meaning of the control file data. Some examples are

   tbackup.movelist  tbackup.updatescript
   blebberfiler.archivecontents
   backup_script_of_Joe_User.archivedescription

The user-supplied control script should look at the label to decide what to do with the control data. This way, control files with unknown labels can be ignored, and afio archives maintain some degree of portability between different programs that restore or index them.

Control file labels that are intended to be portable between different backup programs could be defined in the future.

Making control files. When making an archive, afio reads a stream containing the names of the files (directories, ...) to put in the archive. This stream may also contain `control file generators', which are lines with the following format:

    //--sourcename label

Here, the //-- sequence signals that a control file is to be made, sourcename is the path to a file containing the control file data, and label is the control file label. The sourcename must be a regular file or a symlink to a regular file.

A control file will show up as

   //--CONTROL_FILE/label

in an archive listing, where label is the control file label.

Control scripts. A control script is supplied to afio with the

-D controlscript

command line option. The controlscript must be an executable program. The script is run whenever afio encounters a control file while doing a -i -t or -r operation. Afio will supply the control file label as an argument to the script. The script should read the control file data from its standard input. If the script exits with a non-zero exit status, afio will issue a warning message.

If a contol file is encountered and no -D option is given, afio will issue a warning message. To suppress the warning message and ignore all control scripts, -D "" can be used.

An example of a control script is

  #!/bin/sh
  if [ $1 = "afio_example.headertext" ]; then
    #the headertext control file is supposed to be packed as the first
    #entry of the archive
    echo Archive header:
    cat -
    echo Unpack this archive? y/n
    #stdout is still connected to the tty, read the reply from stdout
    read yn <&1
    if [ "$yn" = n ]; then
      #abort
      kill $PPID
    fi
  else
    echo Ignoring unknown control file.
    cat - >/dev/null
  fi

Afio never compresses the control file data when storing it in an archive, even when the -Z option is used. When a control file is encountered by cpio(1) or an afio with a version number below 2.4.1, the data will be unpacked to the filesystem, and named CONTROL_FILE/label where label is the control file label.  

BUGS

Restricts pathnames to 1023 characters and 255 meaningful elements.

There is no sequence information within multi-volume archives. Input sequence errors generally masquerade as data corruption. A solution would probably be mutually exclusive with cpio(1) compatibility.

Degenerate uses of symbolic links are mangled by pathname optimization. For example, assuming that "usr.src" is a symbolic link to "/usr/src", the pathname "usr.src/../bin/cu" is mis-optimized into "bin/cu" (rather than "/usr/bin/cu").

The Linux floppy drivers below kernel version 1.1.54 do not allow afio to find out about floppy write errors while writing. If you are running a kernel below 1.1.54, afio will happily fail to write to (say) a write protected disk and not report anything wrong! The only way to find out about write errors in this case is by watching the kernel messages, or by switching on the verify (-K) option.

The code for -F (and -f and -K ) is a complete mess. It will probably work in the normal case, but don't expect it to handle a write/verify error correctly. If you get such an error, best thing is to restart afio completely.

An archive created with a command like 'find /usr/src/linux -print | afio -o ...' will not contain the ownership and permissions of the /usr and /usr/src directories. If these directories are missing when restoring the archive, afio will recreate them with some default ownership and permissions.

Afio will not restore time stamps on symlinks, and will often change the time stamp on a directory after having restored it.

A restore using decompression will fail if the gzip binary used by afio is overwritten, by afio or by another program, during the restore. The restore will also fail if any shared libraries needed to start gzip are overwritten during the restore. afio should not normally be used to overwrite the system files on a running system. If it is used in this way, a flag like -Y /bin/gzip can often be added to prevent failure.

SEE ALSO

AUTHORS

Index

NAME

SYNOPSIS

DESCRIPTION

OPTIONS

NOTES

CONTROL FILES

BUGS

SEE ALSO

AUTHORS