How to Count Lines in a File in Linux

Count lines, words and bytes with wc, with useful variations for logs and source files.

Short answer

$ wc -l file.txt

The -l option counts newline characters, which is the standard quick line count for a text file.

`wc` is the small Unix utility for counting lines, words, characters and bytes. It is useful in scripts because its output is predictable and easy to pipe into other commands.

Step by step

1 Count lines

$ wc -l file.txt

Prints the number of newline characters and the filename.

2 Count several files

$ wc -l *.log

Shows a count for each matching file plus a total.

3 Count lines from a pipeline

$ grep -i "error" app.log | wc -l

Counts the number of matching output lines.

4 Count words and bytes too

$ wc file.txt

Without options, wc reports lines, words, bytes and the filename.

Tips worth knowing

For source-code statistics, remember that blank and comment lines are still lines.
When counting command output, prefer `wc -l` over parsing formatted output with shell string operations.
A final line without a newline can make intuitive line counting differ from wc -l.