what command creates an empty file when the file specified doesn't exist and also updates the time stamp
touch
what command copies one or more ordinary files, including text, executable program files, and directories
cp
what command renames files or moves one or more files between directories
mv
what command determines file types and displays file type information
file
what command displays the contents of one or more text files on the terminal
cat
what command displays the contents of files one screen at a time
more
what command displays a select number of lines from the beginning of files
head
what command displays a select number of lines from the end of files
tail
what command clears the display screen of all data and re-displays the cursor at the top of the page
clear
what command displays who is logged into the system
who
what command displays the current user ID
whoami
what command creates a shell with the specified user ID
su
what command creates or changes a password associated with a user name
passwd
what command displays the current environment variables for the user or, if an environment variable is specified, sets it to a new value and displays the modified environment
env
what command displays the groups to which the specified user is a member
groups
what command displays information about the current user or another specified user