Summary

Want to count the number of lines in a Linux file?

We’ll provide you with a few different ways to do it.

Counting the number of lines gives information about how small or large a given file is.

A linux terminal open on a laptop running Ubuntu

Hannah Stryker / How-To Geek

Why Count the Lines in a File?

Like all computer files, Linux files come indifferent sizes.

Some files are big, and some are small.

Sample test file containing ten lines of different text

One way of doing this is to count the number of lines a file has, albeit roughly.

Counting the lines of a file is useful for various reasons.

you could verify the format or structure of the file.

Linux terminal displaying total line count output with the help of wc command with -l flag

Line count can help you to filter and analyze the output of other commands.

For example, one can analyze the number of lines in a system log file.

This will help you to check the approximate number of errors present in the system log file.

Linux terminal displaying the output of wc command without any option followed by filename

Line count also gives you an estimate of the total items in a directory.

This can be useful for debugging software or tracking changes to a document.

Some of these commands arewc,sed,grep, andawk.

Linux terminal displaying the wc command having multiple text files as arguments.

ABash scriptcan also help calculate the line count in a file.

We will explore each of these methods with an example.

Simply use the wc command.

Linux terminal displays the line count of all files in a directory with the help of the wc command.

This command outputs the number of words, lines, and characters in a file.

Let’s consider a sample file, example.txt.

To get detailed information about the file, use the wc command without any option.

Wc command on Linux terminal with the display of the line count only.

The wc command can also display the line count of all the files present inside a directory.

To do this, use the wc command with the-loption followed by the asterisk operator.

As in all the above cases, the output shows the filename along with the line count.

Linux terminal displaying the cat command piped with wc command and output that displays ten lines count.

To show the line count without the filename, run:

Here, the wc command uses input redirection.

This will give the content of the example file to the wc command.

It then directly counts lines without displaying the filename.

Linux terminal that describes the sed command output.

It performs various operations on a file, such as inserting, deleting, replacing, or appending text.

The sed command takes the input from a file or standard input.

The sed command can also count the total lines of a specified file.

Linux terminal that displays the Linux grep command searching for a specific pattern.

It can take different arguments to print the line numbers.

The sed command with the options-nand$=can count and display the total number of lines in the file.

The$=signifies the last line of the file.

Linux terminal displays the output of the grep command when it searches for line counts that do not contain a defined pattern.

It ensures that only the line number is printed to the standard output.

To get an overall number of lines in the file, use:

3.

The defined pattern is a regular expression that specifies what to search for.

Linux terminal displays the output of the grep command when it searches for line counts that do not contain a defined pattern.

If you don’t specify the file, grep reads from the standard input.

Add the-cflag with the grep command to determine the count of lines matching a specific pattern.

For this, use the-vflag with grep:

There is another regular expression pattern (".

Output of grep command with -c option.

*") with a dot and asterisk sign.

It matches any line with zero or more occurrences of any character.

Unlike the above two commands, it doesn’t look for a specific word.

Output of grep command with -hc option that displays the file name.

It simply counts and outputs the number of lines in example.txt that have one or more characters.

The-cflag ensures that only the line count is displayed, not the actual line content that matches the pattern.

To add the file name in the above output, simply include the-Hflag:

4.

Linux terminal displaying the awk script to count lines.

It’s particularly strong in pattern matching and processing fields and records.

you’re free to use the awk command to count the lines in a file.

It uses the AWK programming language to print the total number of records (lines) in the file.

Linux terminal displaying nl command output.

It’s useful for viewing or printing files with line numbers.

you’re free to use the nl command with filename to count the lines in a specified file.

This command will display both the line numbers and line content in the example.txt file.

Linux terminal displaying the nl command piped with tail and awk command.

It involves additional processing and rendering of output that is not necessary for the specific task of counting lines.

The nl command adds a line number at the beginning of each line.

The-1option tells the tail command to show only one line.

Linux terminal that displays the chmod command with sample file as input.

Till now, you have the output “10 uname Command.”

you’ve got the option to also use it to count the lines in a file.

The wc command gets the count of lines and stores it in the linecount variable.

Linux terminal that displays the running of the bash script and its output.

Like counting lines, counting Linux files in a directory also helps you manage the system more efficiently.

Knowing theLinux file structureis also important.

Consider the main pillar of Linux filestheinodes.

If you run out of these in your system, you will have a tough day.

These are very limited in numbers and store crucial data in your system.

Knowing these will not only help you to manage and perform tasks but also ease the system maintenance tasks.