Drives, Mounts, and File Systems

• The /proc file system also contains information about the disk drives present in the system and the file systems mounted from them.
• File Systems; the /proc/filesystems entry displays the file system types known to the kernel. File systems can be loaded and unloaded dynamically as kernel modules. The contents of /proc/filesystems list only file system types that either are statically linked into the kernel or are currently loaded.
• The /proc/locks contains information on locks that are held on open files.
  • It is generated by the get_locks_status() function in /usr/src/linux/fs/locks.c.
  • Each line represents lock information for a specific file, and documents the type of lock applied to the file.
  • The functions fcntl() and flock() are used to apply locks to files.
  • The kernel may also apply locks to files when needed.
• Drives and Partitions; the /proc file system includes information about devices connected to both IDE controllers and SCSI controllers (if the system includes them).
  • Each IDE device directory contains several entries providing access to identification and configuration information for the device. A few of the most useful are listed here:
    • model contains the device's model identification string.
    • media contains the device's media type. Possible values are disk, cdrom, tape, floppy, and UNKNOWN.
    • capacity contains the device's capacity, in 512-byte blocks.

    $ cat /proc/ide/ide1/hdc/media
    $ cat /proc/ide/ide1/hdc/model
    $ cat /proc/scsi/scsi
    $ cat /proc/sys/dev/cdrom/info
    

  • The /proc/partitions entry displays the partitions of recognized disk devices. For each partition, the output includes the major and minor device number, the number of 1024-byte blocks, and the device name corresponding to that partition.
• Mounts; the /proc/mounts file provides a summary of mounted file systems that you would normally expect in /etc/mtab. Each line corresponds to a single mount descriptor and lists the mounted device, the mount point, and other information.
  • The first element on the line is the mounted device.
  • The second element is the mount point, the place in the root file system at which the file system contents appear. For the root file system itself, the mount point is listed as /. For swap drives, the mount point is listed as swap.
  • The third element is the file system type. Currently, most GNU/Linux systems use the ext2 file system for disk drives, but DOS or Windows drives may be mounted with other file system types, such as fat or vfat. Most CD-ROMs contain an iso9660 file system.
  • The fourth element lists mount flags. These are options that were specified when the mount was added.