(cpio.info.gz) Tutorial

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 2 Tutorial
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 GNU cpio performs three primary functions.  Copying files to an archive,
 Extracting files from an archive, and passing files to another directory
 tree.  An archive can be a file on disk, one or more floppy disks, or
 one or more tapes.
 
    When creating an archive, cpio takes the list of files to be
 processed from the standard input, and then sends the archive to the
 standard output, or to the device defined by the '-F' option.  
 Copy-out mode.  Usually find or ls is used to provide this list to the
 standard input.  In the following example you can see the possibilities
 for archiving the contents of a single directory.
 
      % ls | cpio -ov > directory.cpio
 
    The '-o' option creates the archive, and the '-v' option prints the
 names of the files archived as they are added.  Notice that the options
 can be put together after a single '-' or can be placed separately on
 the command line.  The '>' redirects the cpio output to the file
 'directory.cpio'.
 
    If you wanted to archive an entire directory tree, the find command
 can provide the file list to cpio:
 
      % find . -print -depth | cpio -ov > tree.cpio
 
    This will take all the files in the current directory, the
 directories below and place them in the archive tree.cpio.  Again the
 '-o' creates an archive, and the '-v' option shows you the name of the
 files as they are archived.   Copy-out mode.  Using the '.' in
 the find statement will give you more flexibility when doing restores,
 as it will save file names with a relative path vice a hard wired,
 absolute path.  The '-depth' option forces 'find' to print of the
 entries in a directory before printing the directory itself.  This
 limits the effects of restrictive directory permissions by printing the
 directory entries in a directory before the directory name itself.
 
    Extracting an archive requires a bit more thought because cpio will
 not create directories by default.  Another characteristic, is it will
 not overwrite existing files unless you tell it to.
 
      % cpio -iv < directory.cpio
 
    This will retrieve the files archived in the file directory.cpio and
 place them in the present directory.  The '-i' option extracts the
 archive and the '-v' shows the file names as they are extracted.  If you
 are dealing with an archived directory tree, you need to use the '-d'
 option to create directories as necessary, something like:
 
      % cpio -idv < tree.cpio
 
    This will take the contents of the archive tree.cpio and extract it
 to the current directory.  If you try to extract the files on top of
 files of the same name that already exist (and have the same or later
 modification time) cpio will not extract the file unless told to do so
 by the -u option.   Copy-in mode.
 
    In copy-pass mode, cpio copies files from one directory tree to
 another, combining the copy-out and copy-in steps without actually using
 an archive.  It reads the list of files to copy from the standard input;
 the directory into which it will copy them is given as a non-option
 argument.   Copy-pass mode.
 
      % find . -depth -print0 | cpio --null -pvd new-dir
 
    The example shows copying the files of the present directory, and
 sub-directories to a new directory called new-dir.  Some new options are
 the '-print0' available with GNU find, combined with the '--null' option
 of cpio.  These two options act together to send file names between find
 and cpio, even if special characters are embedded in the file names.
 Another is '-p', which tells cpio to pass the files it finds to the
 directory 'new-dir'.
 
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