wc and nl

The wc (word count) command shows the total count of words in a file.

$ wc /etc/passwd
 96     265    5925 /etc/passwd

It display the number of lines, number of words and number of bytes, respectively.

To just see just the count of a certain field, use the -l, -w, or -c respectively.

$ wc -l /etc/passwd
96

Another command you can use to check the count of lines on a file is the nl (number lines) command.

file1.txt
i
like
turtles

$ nl file1.txt
1. i
2. like
3. turtles