DF and Du commands

Detailed DF command usage

A: displays the disk usage of all file systems and partitions.
I: displays the I-nodes usage.
K: The size is represented by K (default)
T: displays the disk usage of all partitions in a file system.
X: displays the disk usage of all partitions of a file system.
T: displays the file system name of each partition.
Common commands: DF-Hi

Operation DetailsThe reference command DF can display the maximum available space and usage of all file systems. See the following example:

# DF-H
Filesystem size used avail capacity mounted on
/Dev/ad0s1a 1.9g 389 m 1.4G 21%/
Devfs 1.0 K 1.0 K 0b 100%/dev
/Dev/ad0s1d 989 M 54 K 910 m 0%/tmp
/Dev/ad0s1f 4.8g 3.8g 657 M 86%/usr
/Dev/ad0s1e 1.9g 149 m 1.6g 8%/var
/Dev/ad0s1g 26G 890 K 24g 0%/volume2
/Dev/da0s1d 325g 261g 38g 87%/volume1

The-H parameter is added to indicate that the "human-readable" output is used, that is, the file system uses readable formats such as GB and MB.

The first and last fields output by the preceding command are the File System and Its mount point. We can see that the/dev/ad0s1a partition is mounted under the root directory. We mentioned in the previous section that ad represents the IDE hard disk, while S1 represents the first primary sector. I have another SCSI hard disk named Da, which has a large capacity and is mainly used to store data. Devfs is a special file system. It is not a real disk, but a Virtual File System that FreeBSD uses to manage system hardware devices.

The following four fields, size, used, avail, and capacity, are the capacity, used size, remaining size, and percentage of the shard. When the hard disk capacity is full, you may see that the percentage used exceeds 100%, because FreeBSD will leave some space for the root, so that when the root file system is full, you can also write something to the file system for management.

In addition, we can also use parameter-I to view the current inode usage of the file system. Sometimes, although the file system still has space, if there is not enough inode to store the file information, it will not be able to add new files.

# DF-ih
Filesystem size used avail capacity iused ifree % iused mounted on
/Dev/ad0s1a 1.9g 389 m 1.4G 21% 20495 262127/
Devfs 1.0 K 1.0 K 0b 100% 0 0 100%/dev
/Dev/ad0s1d 989 M 62 k 910 m 0% 24 141286 0%/tmp
/Dev/ad0s1f 4.8g 3.8g 657 M 86% 311439 348015/usr
/Dev/ad0s1e 1.9g 149 m 1.6g 8% 1758 280864/var
/Dev/ad0s1g 26G 890 K 24g 0% 12 3532786 0%/volume2
/Dev/da0s1d 325g 261g 38g 87% 707277 43311409/volume1
We can see that the number of inode used in the root directory is 20495, and there are 262127 available inode.

Tips
Do you still remember what inode is? Inode is the basic information (metadata) used to store archives and directories, including the time, file name, user, and group. When dividing a sector, the system will first make a bunch of inode for later use. The number of inode is related to the total number of files and directories that can be created in the system. If most of the files to be stored are small, there will be a large number of files on hard disks of the same size, that is, a large number of inode are required to mount files and directories.

Du: query the disk space used by an archive or directory

A: displays the disk space occupied by all directories and each file in the second directory.
B: The size is represented by bytes (the default value is K bytes)
C: add the total value (default)
S: only display the total size of each file (summarize)
X: only calculate the files of the same file system.
L: Calculate the size of all files
Common commands: Du-

Operation DetailsThe reference command du can display the disk space occupied by all files in each directory in the unit of subdirectories in the specified directory. For example:

# Du-H/etc
104 K/etc/defaults
6.0 K/etc/X11
8.0 K/etc/Bluetooth
4.0 K/etc/gnats
52 K/etc/ISDN
388 K/etc/mail
68 K/etc/mtree
2.0 k/etc/NTP
38 K/etc/PAM. d
44 K/etc/periodic/daily
6.0 K/etc/periodic/monthly
42 k/etc/periodic/security
16 K/etc/periodic/weekly
110 K/etc/periodic
6.0 K/etc/PPP
318 K/etc/rc. d
2.0 k/etc/skel
130 K/etc/ssh
10 K/etc/SSL
1.7 m/etc
The-H parameter is used to display the human-readable format. In the application, we can use the "du" command to check which directory occupies the most space. However, the output result of DU is usually very long. We can add the-S parameter to omit the subdirectories in the specified directory, and only display the total combination of the directories:

# Du-SH/etc
1.7 m/etc
When viewing the usage of the Directory, we can export the output results to the sort command for sorting to know which file has used the most space:

# du/etc | sort-Nr | more
1746/etc
388/etc/mail
318/etc/rc. d
130/etc/ssh
110/etc/periodic
104/etc/defaults
68/etc/mtree
52/etc/ ISDN
44/etc/periodic/daily
42/etc/periodic/Security
38/etc/PAM. d
16/etc/periodic/weekly
10/etc/SSL
8/etc/Bluetooth
6/etc/PPP
6/ ETC/periodic/monthly
6/etc/X11
4/etc/gnats
2/etc/skel
2/etc/NT P
the sort parameter-Nr indicates that reverse sorting is performed by numerical sorting. Because we want to sort the directory size, we cannot use the human-readable size output, otherwise, the directory size may contain letters such as K and M, which may result in incorrect sorting.