cp file1 file2 = copy file1 and call it file2
mv file1 file2 move or rename file1 to file2
rm file = remove a file
rmdir directory = remove a directory
cat file = display a file
more file = display a file a page at a time
head file = display the first few lines of a file
tail file = display the last few lines of a file
grep 'keyword' file = search a file for keywords
wc file = count number of lines/words/characters in file