chmod mode file-name change file and directory attributes
tar -Mcvf device-name directory-name backup files to a removable device
cd /directory-name change directory
pwd display name of current directory
df display free disk space
clear clear the screen
cp file-name copy file
date change system date
rm file-name remove file
rm -R directory-name
rm -rf directory-name
remove subdirectory, subdirectory tree or subdirectories of files
ls -l display list of files with details
ls display list of file names
find . -name file-name display info about a specific file
dump copy disk images
echo text display text to screen
gedit file-name screen (visual) text editor
ed file-name basic line editor (non screen-based text editor)
exit close a DOS window or a Linux terminal window
diff file1 file2 compare contents of files
fdisk partition hard drive
grep find character strings in files
mke2fs /dev/fd0
fdformat /dev/fd0H1440 ; mkfs -t ext2 -c /dev/fd0H1440
format a floppy
man command-name
info command-name
display detailed command information
free display memory usage
mkdir directory-name create a directory
more file-name
less file-name
display files page by page
lpr print a file
gzip file-name ;  tar file-name.gz compress files and bundle them into one file
mv old-name new-name rename file
tar -Mxpvf device-name restore files from a removable device
env display current settings of environmental variables
env variable=value assign values to environmental variables
date options change system time
cat display file contents
cpio copy entire directory structure
command-name --help display summary of command line options
w display a list of users logged on
uname -a reports OS ver/ type
clear clears the command console
top monitor CPU and mem loads
tail output last 10 lines of a file
touch create a file if it does not exsit or updates the time stamp of an existing file
ntsysv -K
ntsysv -S
sets programs and services that should launch for current run level
ps -aux lists all the processes running