Viewing Mounted File Systems and Swap

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One of the first activities you would perform when interested in file systems is to see what file systems are currently mounted on your system and their characteristics. The df command produces a listing of mounted file systems and some space-related information on each. The following is an example shows issuing the df command with the --help option, then just df, and finally df -h:

 # df --help Usage: df [OPTION]... [FILE]... Show information about the filesystem on which each FILE resides, or all filesystems by default. Mandatory arguments to long options are mandatory for short options too.   -a, --all             include filesystems having 0 blocks   -B, --block-size=SIZE use SIZE-byte blocks   -h, --human-readable  print sizes in human readable format (e.g., 1K 234M 2G)   -H, --si              likewise, but use powers of 1000 not 1024   -i, --inodes          list inode information instead of block usage   -k                    like --block-size=1K   -l, --local           limit listing to local filesystems       --no-sync         do not invoke sync before getting usage info (default)   -P, --portability     use the POSIX output format       --sync            invoke sync before getting usage info   -t, --type=TYPE       limit l isting to filesystems of type TYPE   -T, --print-type      print filesystem type   -x, --exclude-type=TYPE   limit listing to filesystems not of type TYPE   -v                    (ignored)       --help     display this help and exit       --version  output version information and exit SIZE may be (or may be an integer optionally followed by) one of following: kB 1000, K 1024, MB 1,000,000, M 1,048,576, and so on for G, T, P, E, Z, Y. Report bugs to <bug-fileutils@gnu.org>. [root@linuxdev root]# df Filesystem           1K-blocks      Used Available Use% Mounted on /dev/hda5               381139    179034    182427  50% / /dev/hda1                46636     14547     29681  33% /boot /dev/hda3              1423096    265596   1085208  20% /home none                     46928         0     46928   0% /dev/shm /dev/hda2              3889924   2800228    892100  76% /usr /dev/hda6               256667     70926    172489  30% /var /dev/hdb1             38464340  29211248   7299188  81% /home/linuxconnect/backup # df -h Filesystem            Size Used Avail Use% Mounted on /dev/hda5             372M 175M 178M 50% / /dev/hda1             45M  15M  28M  33% /boot /dev/hda3            1.4G 260M 1.0G  20% /home none                  46M    0  45M   0% /dev/shm /dev/hda2            3.7G 2.7G 871M  76% /usr /dev/hda6            251M  70M 168M  30% /var /dev/hdb1             37G  28G 6.9G  81% /home/linuxconnect/backup 

The first option produces a listing of all options to the df command. The second time you issued the df command with no options. Finally, you produced an output with the -h option that shows the output in an easy-to-read format.

Another important topic related to file systems is swap space.

You can view swap information on most Linux variants using the parted command, as shown in the following example:

 # parted GNU Parted 1.4.24 Copyright (C) 1998, 1999, 2000, 2001, 2002 Free Software Foundation, Inc. This program is free software, covered by the GNU General Public License. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PUR- POSE. See the GNU General Public License for more details. Using /dev/hda Information: The operating system thinks the geometry on /dev/hda is 784/255/63. (parted) help   check MINOR                   do a simple check on the filesystem   cp [FROM-DEVICE]  FROM-MINOR TO-MINOR      copy filesystem to another partition   help [COMMAND]                prints general help, or help on COMMAND   mklabel LABEL-TYPE            create a new disklabel (partition table)   mkfs MINOR FS-TYPE            make a filesystem FS-TYPE on partititon MINOR   mkpart PART-TYPE [FS-TYPE] START END       make a partition   mkpartfs PART-TYPE FS-TYPE START END       make a partition with a filesystem   move MINOR START [END]         move partition MINOR   name MINOR NAME              name partition MINOR NAME   print                        display the partition table   quit                         exit program   resize MINOR START END       resize filesystem on partition MINOR   rm MINOR                     delete partition MINOR   select DEVICE                choose the device to edit   set MINOR FLAG STATE         change a flag on partition MINOR (parted) print Disk geometry for /dev/hda: 0.000-6149.882 megabytes Disk label type: msdos Minor    Start       End     Type      Filesystem  Flags 1          0.031     47.065  primary   ext3        boot 2         47.065   3906.430  primary   ext3 3       3906.431   5318.393  primary   ext3 4       5318.394   6149.882  extended 5       5318.424   5702.761  logical   ext3 6       5702.792   5961.621  logical   ext3 7       5961.652   6149.882  logical   linux-swap (parted) quit [root@linuxdev root]# 

In this example, you issued parted, then the help option, then the print option, and finally the quit option.

As you can see, the output from parted has to be interpreted. The boot partition, for instance, has a Start and End in MB. This partition is shown in the df -h output as being 45M. The next partition, which is 2, corresponds to / on the df -h output that shows a size of 372M. Because the parted output has a Start and End entry you have to perform a little arithmetic in order to determine the size of the partition. When you get to linux-swap, you have to subtract the Start from End to see the size of this partition. The partitions are not listed in the same order in the two outputs. You can also use fdisk to view all the partitions including swap space, as shown in the following listing:

 # fdisk /dev/hda -l Disk /dev/hda: 255 heads, 63 sectors, 784 cylinders Units = cylinders of 16065 * 512 bytes    Device Boot    Start       End    Blocks   Id  System /dev/hda1   *         1         6     48163+  83  Linux /dev/hda2             7       498   3951990   83  Linux /dev/hda3           499       678   1445850   83  Linux /dev/hda4           679       784    851445    5  Extended /dev/hda5           679       727    393561   83  Linux /dev/hda6           728       760    265041   83  Linux /dev/hda7           761       784    192748+  82  Linux swap # 

This output is different than parted and has the added column of Blocks, which makes it easier to determine the size of swap on this disk.

You can also use parted and fdisk to manipulate the partitions.

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    Linux on HP Integrity Servers. A System Administrator's Guide
    Linux on HP Integrity Servers: A System Administrators Guide
    ISBN: 0131400002
    EAN: 2147483647
    Year: 2004
    Pages: 100

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