dmesg [options]

System administration command. Display the system control messages from the kernel ring buffer. This buffer stores all
messages since the last system boot, or the most recent ones if the buffer has been filled.

dirname pathname

Print pathname, excluding the last level. Useful for stripping the actual filename from a pathname. If there are no slashes (no directory
levels) in pathname, dirname prints . to indicate the current directory. See also basename.

dircolors [options] [file]

Set the color options for the ls command. dircolors outputs shell commands which, when evaluated, update the LS_COLORS environment
variable. If you specify a file, dircolors reads it to determine which colors to use. Otherwise, it uses a default set of colors. If the shell is not specified, dircolors checks the SHELL environment variable

dir [options] [file]

List directory contents. dir is equivalent to the command ls -C -b (list files in columns, sorted vertically, special characters escaped),
and it takes the same arguments as ls. This is an alternate invocation of the ls command and is provided for the convenience of
those converting from Microsoft Windows and the DOS shell.

dig [@server] [options] [name] [type] [class] [query-options]
dig @server name type
dig -h

diff3 [options] file1 file2 file3

Compare three files and report the differences. No more than one of the files may be given as - (indicating that it is to be read from
standard input). The output is displayed with the following codes:
= = = =
All three files differ.
= = = =1
file1 is different.
= = = =2
file2 is different.
= = = =3
file3 is different.

diff [options] file1 file2

df [options] [name]

Report the amount of free disk space available on all mounted filesystems or on the given name. (df cannot report on unmounted
filesystems.) Disk space is shown in 1 KB blocks (default) or 512- byte blocks if the environment variable POSIXLY_CORRECT is set.
name can be a device name (e.g., /dev/hd*), the directory name of a mounting point (e.g., /usr), or a directory name (in which case df reports on the entire filesystem in which that directory is mounted).

devdump isoimage

Interactively display the contents of the device or filesystem image isoimage. devdump displays the first 256 bytes of the first 2048-
byte sector and waits for commands. The prompt shows the extent number (zone) and offset within the extent, and the contents
display at the top of the screen.

depmod [options] modules

System administration command. Create a dependency file for the modules given on the command line. This dependency file can be
used by modprobe to automatically load the relevant modules. The normal use of depmod is to include the line /sbin/depmod -a in
one of the files in /etc/rc.d so that the correct module dependencies will be available after booting the system.