mtree —
format of mtree dir hierarchy files
The mtree format is a textual format that describes a
  collection of filesystem objects. Such files are typically used to create or
  verify directory hierarchies.
An mtree file consists of a series of lines, each
  providing information about a single filesystem object. Leading whitespace is
  always ignored.
When encoding file or pathnames, any backslash character or
    character outside of the 95 printable ASCII characters must be encoded as a
    backslash followed by three octal digits. When reading mtree files, any
    appearance of a backslash followed by three octal digits should be converted
    into the corresponding character.
Each line is interpreted independently as one of the following
    types:
  - Blank
- Blank lines are ignored.
- Comment
- Lines beginning with #are ignored.
- Special
- Lines beginning with /are special commands that
      influence the interpretation of later lines.
- Relative
- If the first whitespace-delimited word has no /characters, it is the name of a file in the current directory. Any
      relative entry that describes a directory changes the current
    directory.
- dot-dot
- As a special case, a relative entry with the filename
      .. changes the current directory to the parent
      directory. Options on dot-dot entries are always ignored.
- Full
- If the first whitespace-delimited word has a /character after the first character, it is the pathname of a file relative
      to the starting directory. There can be multiple full entries describing
      the same file.
Some tools that process mtree files may
    require that multiple lines describing the same file occur consecutively. It
    is not permitted for the same file to be mentioned using both a relative and
    a full file specification.
Two special commands are currently defined:
  - /set
- This command defines default values for one or more keywords. It is
      followed on the same line by one or more whitespace-separated keyword
      definitions. These definitions apply to all following files that do not
      specify a value for that keyword.
- /unset
- This command removes any default value set by a previous
      /setcommand. It is followed on the same line by
      one or more keywords separated by whitespace.
After the filename, a full or relative entry consists of zero or more
  whitespace-separated keyword definitions. Each such definition consists of a
  key from the following list immediately followed by an '=' sign and a value.
  Software programs reading mtree files should warn about unrecognized keywords.Currently supported keywords are as follows:
  - cksum
- The checksum of the file using the default algorithm specified by the
      cksum(1) utility.
- device
- The device number for block or char
      file types. The value must be one of the following forms:
    
      - format,major,minor[,subunit]
- A device with major, minor
          and optional subunit fields. Their meaning is
          specified by the operating's system format. See
          below for valid formats.
- number
- Opaque number (as stored on the file system).
 The following values for format are
        recognized: native, 386bsd,
        4bsd, bsdos,
        freebsd, hpux,
        isc, linux,
        netbsd, osf1, sco,
        solaris, sunos,
        svr3, svr4, and
        ultrix. See mknod(8) for
        more details. 
- contents
- The full pathname of a file that holds the contents of this file.
- flags
- The file flags as a symbolic name. See
      chflags(1) for information
      on these names. If no flags are to be set the string “none”
      may be used to override the current default.
- gid
- The file group as a numeric value.
- gname
- The file group as a symbolic name.
- ignore
- Ignore any file hierarchy below this file.
- inode
- The inode number.
- link
- The target of the symbolic link when type=link.
- md5
- The MD5 message digest of the file.
- md5digest
- A synonym for md5.
- mode
- The current file's permissions as a numeric (octal) or symbolic
    value.
- nlink
- The number of hard links the file is expected to have.
- nochange
- Make sure this file or directory exists but otherwise ignore all
      attributes.
- optional
- The file is optional; do not complain about the file if it is not in the
      file hierarchy.
- resdevice
- The “resident” device number of the file, e.g. the ID of the
      device that contains the file. Its format is the same as the one for
      device.
- ripemd160digest
- The RIPEMD160 message digest of the file.
- rmd160
- A synonym for ripemd160digest.
- rmd160digest
- A synonym for ripemd160digest.
- sha1
- The FIPS 160-1 (“SHA-1”) message digest of the file.
- sha1digest
- A synonym for sha1.
- sha256
- The FIPS 180-2 (“SHA-256”) message digest of the file.
- sha256digest
- A synonym for sha256.
- sha384
- The FIPS 180-2 (“SHA-384”) message digest of the file.
- sha384digest
- A synonym for sha384.
- sha512
- The FIPS 180-2 (“SHA-512”) message digest of the file.
- sha512digest
- A synonym for sha512.
- size
- The size, in bytes, of the file.
- time
- The last modification time of the file.
- type
- The type of the file; may be set to any one of the following:
    
    
      - block
- block special device
- char
- character special device
- dir
- directory
- fifo
- fifo
- file
- regular file
- link
- symbolic link
- socket
- socket
 
- uid
- The file owner as a numeric value.
- uname
- The file owner as a symbolic name.
Themtree utility appeared in
  4.3BSD-Reno. The MD5 digest capability was added in
  FreeBSD 2.1, in response to the widespread use of
  programs which can spoof
  cksum(1). The SHA-1 and RIPEMD160
  digests were added in FreeBSD 4.0, as new attacks have
  demonstrated weaknesses in MD5. The SHA-256 digest was added in
  FreeBSD 6.0. Support for file flags was added in
  FreeBSD 4.0, and mostly comes from
  NetBSD. The “full” entry format was
  added by NetBSD.