wc command (word count)

The Linux word count command is named wc. The wc command counts the number of characters, words, and lines that are contained in a text stream. If that sounds simple or boring, it’s anything but; the wc command can be used in Linux command pipelines to do all sorts of interesting things.

Linux wc command examples (words, lines, characters)
In its most basic use, the wc command can be used to count the number of characters, words, and lines in a file, like this:

$ wc /etc/passwd
65 185 3667 /etc/passwd
If you just want to know the number of lines in a file just add the -l argument, like this:

$ wc -l /etc/passwd
65 /etc/passwd
Or, if you want to know the number of words in a file, add the -w argument, like this:

$ wc -w MyStory.txt
185 MyStory.txt
Using the Linux wc command in command pipelines
The wc command follows the paradigm of reading input from STDIN and writing output to STDOUT, so it can be used in all sorts of Linux command pipelines. This command shows the number of users currently logged into your Linux system:

who | wc -l
It does that by piping the output of the who command into the input of the wc command, which in this case is used to count the number of lines of output in the who command.

Similarly, this next command shows the number of processes currently running on your Linux system:

ps -e | wc -l
This works the same way as the previous example: Generate output using one command (the ps command), and use the wc -l command to count the number of lines of output from that command.

 

source: alvinalexander.com/unix/edu/examples/wc.shtml