`wc` Count lines, words and bytes

Counts the lines, words and bytes in files or in piped input. Use it to see how big a file is, or to count how many results another command produced.

Synopsis

wc [-clmw] [FILE]...
COMMAND | wc -l

Option or form	What it does
`-l`	Count lines (newline characters)
`-w`	Count words, meaning runs of non-blank characters
`-c`	Count bytes
`-m`	Count characters. Differs from -c when text has multi-byte characters such as accented letters

Lines, words and bytes in a file

wc notes.txt

Count lines only

wc -l notes.txt

Count the lines in several files at once

wc -l notes.txt app.log data.csv

Count how many entries are in a folder

ls docs | wc -l

Count matching lines from another command

grep -i error app.log | wc -l

Count the files under a folder, including sub-folders

find docs -type f | wc -l

wc -l counts newline characters. A last line with no newline at the end is not counted.
With several files, wc adds a total line at the end.
When reading from a file name, wc prints the name after the count. When reading from a pipe or with <, it prints the number alone, which is easier to use in scripts.
On macOS the numbers are padded with leading spaces. Some scripts compare them as text by mistake. Compare numerically, or strip the spaces with tr -d ' '.
grep -c counts matching lines directly, so grep -c error app.log is shorter than grep error app.log | wc -l.