how to find misspelled words form a file in linux shell command mispelling

many unix systems contain a spellcheck program that examines files for misspelled words. on some systems, the spell program only reads from input, it cannot open files. lets say i have a file called myusers and i want to find any mispellings in this file, i would run this command

spell < myusers

or

spell -l < myusers

all string in the file that spell does not find in the online dictionary are viewed as misspelled words in the file and are dsiplayed on the screen. in this case, the shell opens the file myusers and connects it to the input of spell. the outpu is not redirected, so the otup is displayed on the screen.