The sort command sorts things. Suppose you had a file named alpha.txt that contained the letters of the alphabet on the left margin, but scrambled. A J M B X W ... Then the command: sort alpha.txt would produce: A B C D E F ... on the screen. Sorting the file reversed by the command: sort -r alpha.txt would reverse the alphabetic order of the lines, giving: Z Y X W V U The sort command has many options.