MKFS(VIII) 11/1/73 MKFS(VIII)
NAME
mkfs - construct a file system
SYNOPSIS
/etc/mkfs special proto
DESCRIPTION
Mkfs constructs a file system by writing on the special file
special according to the directions found in the prototype
file proto. The prototype file contains tokens separated by
spaces or new lines. The first token is the name of a file
to be copied onto block zero as the bootstrap program (see
boot procedures(VIII)). The second token is a number spec-
ifying the size of the created file system. Typically it
will be the number of blocks on the device, perhaps dimin-
ished by space for swapping. The next token is the i-list
size in blocks (remember there are 16 i-nodes per block).
The next set of tokens comprise the specification for the
root file. File specifications consist of tokens giving the
mode, the user-id, the group id, and the initial contents of
the file. The syntax of the contents field depends on the
mode.
The mode token for a file is a 6 character string. The
first character specifies the type of the file. (The char-
acters -bcd specify regular, block special, character spe-
cial and directory files respectively.) The second charac-
ter of the type is either u or - to specify set-user-id mode
or not. The third is g or - for the set-group-id mode. The
rest of the mode is a three digit octal number giving the
owner, group, and other read, write, execute permissions
(see chmod(I)).
Two decimal number tokens come after the mode; they specify
the user and group ID's of the owner of the file.
If the file is a regular file, the next token is a pathname
whence the contents and size are copied.
If the file is a block or character special file, two deci-
mal number tokens follow which give the major and minor de-
vice numbers.
If the file is a directory, mkfs makes the entries . and ..
and then reads a list of names and (recursively) file speci-
fications for the entries in the directory. The scan is
terminated with the token $.
If the prototype file cannot be opened and its name consists
of a string of digits, mkfs builds a file system with a sin-
gle empty directory on it. The size of the file system is
the value of proto interpreted as a decimal number. The i-
list size is the file system size divided by 43 plus the
size divided by 1000. (This corresponds to an average size
of three blocks per file for a 4000 block file system and
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MKFS(VIII) 11/1/73 MKFS(VIII)
six blocks per file at 40,000.) The boot program is left
uninitialized.
A sample prototype specification follows:
/usr/mdec/uboot
4872 55
d--777 3 1
usr d--777 3 1
sh ---755 3 1 /bin/sh
ken d--755 6 1
$
b0 b--644 3 1 0 0
c0 c--644 3 1 0 0
$
$
SEE ALSO
file system(V), directory(V), boot procedures(VIII)
BUGS
It is not possible to initialize a file larger than 64K
bytes.
The size of the file system is restricted to 64K blocks.
There should be some way to specify links.
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