vfs File

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Purpose

Describes the virtual file systems (VFS) installed on the system.

Description

The /etc/vfs file describes the virtual file systems installed on the system. The name, type number, and file-system helper program are among the types of information listed in the file. Commands, such as the mount command, the fsck command (file system check), and the mkfs command (make file system), use this information.

The vfs file is an ASCII file, with one record per line. The following are examples of the three types of lines in the vfs file:

  • Comments 
    # This is a comment.
# Comments begin with a # (pound sign).
# Blank lines are ignored.
# The following example only locally defines the default vfs file.
  • General control 
    %defaultvfs jfs nfs
    The fields for the %defaultvfs control line are:
    Item Description
    %defaultvfs Identifies the control line.
    jfs Indicates the default local virtual file system.
    nfs Indicates the remote virtual file system (optional).
  • Entries 
    #Name   Type   Mount Helper      Fs. helper
jfs      3     none               /sbin/helpers/v3fshelper
nfs      2     /etc/nfsmnthelp    none
cdrfs    5     none               none

The comments are in text for explanatory purposes. The general control lines, which are designated by a % (percent) character, configure the actions of the following commands:

For example, a line like %defaultvfs indicates the default local virtual file system is used if no VFS is specified by the mount command or in the /etc/filesystems file. The entry is the name of the VFS as indicated in the file. If a second entry is listed on the same line, it is taken to be the default remote VFS. The %defaultvfs control line may leave off the remote VFS specification.

The VFS entries take the following form:

Item Description
name Canonical name of this type of virtual file system.
type Decimal representation of the virtual file system type number for the VFS.
mnt_helper Path name of the mount helper program of this VFS. If a mount helper is not required, the entry should be displayed as none. If this path name does not begin with a slash, it is relative to the /sbin/helpers directory.
fs_helper Path name of the file system helper program of this VFS. If a file system helper is not required, the entry should be none. If this path name does not begin with a slash, it is relative to the /sbin/helpers directory.

Files

Item Description
/etc/filesystems Lists the known file systems and defines their characteristics.