# cat file1
view the contents of a file starting from the first row [man]
# head -2 file1
view first two lines of a file [man]
# less file1
similar to 'more' command but which allows backward movement in the file as well as forward movement [man]
# more file1
view content of a file along [man]
# tac file1
view the contents of a file starting from the last line [man]
# tail -2 file1
view last two lines of a file [man]
# tail -f /var/log/messages
view in real time what is added to a file [man]