There are many utilities available in Linux and Unix systems that allow you to process and filter text files. Cut is a command line utility that allows you to cut parts of lines from specified files or piped data and print the result to standard output. It can be used to cut parts of a line by delimiter, byte position, and character.

In this tutorial, we will show you how to use the Linux cut command through practical examples and detailed explanations of the most common cut options.

How to Use the Cut Command

The syntax for the cut command is as follows:

When using the cut command you must use one and only one of the following options:

  • -f (--fields=LIST) – Select by specifying a field, a set of fields, or a range of fields. This is the most commonly used option.
  • -b (--bytes=LIST) – Select by specifying a byte, a set of bytes, or a range of bytes.
  • -c (--characters=LIST) – Select by specifying a character, a set of characters, or a range of characters.

Other options are:

  • -d (--delimiter) – Specify a delimiter that will be used instead of the default “TAB” delimiter.
  • --complement – complement the selection. When using this option cut will display all bytes, characters or fields except the selected.
  • -s (--only-delimited) – By default cut will print any line that contains no delimiter character. When using this option cut will not print lines not containing delimiters.
  • --output-delimiter – The default is to use the input delimiter as the output delimiter. This option allows you to specify a different output delimiter string.

The cut command can accept zero or more input FILE names. If no FILE is specified, or when FILE is -, cut will read the standard input.

The LIST argument passed to the -f, -b, and -c options can be an integer, multiple integers separated by commas, a range of integer, or multiple integer ranges separated by commas. Each range can be one of the following:

  • N the Nth field, byte or character, starting from 1.
  • N- from the Nth field, byte or character, to the end of the line.
  • N-M from the Nth to the Mth field, byte, or character.
  • -M from the first to the Mth field, byte or character.

How to Cut by Field

Cut command is mostly used to display selected fields from each line of files or the standard input. When not specified the default delimiter is “TAB”.

In the examples below, we will use the following file. All fields are separated by tabs.

test.txt

245:789 4567    M:4540  Admin   01:10:1980
535:763 4987    M:3476  Sales   11:04:1978

To display the 1st and the 3rd field you would use:

cut test.txt -f 1,3
245:789	M:4540
535:763	M:3476

Or if you want to display from the 1st to the 4th field:

cut test.txt -f -4
245:789	4567	M:4540	Admin
535:763	4987	M:3476	Sales

How to cut based on a delimiter

To cut based on a delimiter use the -d option followed by the delimiter you want to use.

For example to display the 1st and 3rd fields using “:” as a delimiter, you would type:

cut test.txt -d ':' -f 1,3
245:4540	Admin	01
535:3476	Sales	11

You can use any single character as a delimiter. In the following example we are using the space character as a delimiter and printing the 2nd field:

echo "Lorem ipsum dolor sit amet" | cut -d ' ' -f 2
ipsum

How to complement the selection

To complement the selection field list use --complement option. This will print only those fields that are not selected with the -f option.

The following command will print all field except the 1st and 3rd:

cut test.txt -f 1,3 --complement
4567	Admin	01:10:1980
4987	Sales	11:04:1978

How to specify an output delimiter

To specify the output delimiter use the --output-delimiter option. For example, to set the output delimiter to _ you would use:

cut test.txt -f 1,3 --output-delimiter='_'
245:789_M:4540
535:763_M:3476

How to cut by Bytes and Characters

Before going any further, let’s make a distinction between bytes and characters.

One byte is 8 bits and can represent 256 different values. When the ASCII standard was established it took into account all of the letters, numbers, and symbols necessary to work with English. The ASCII character table has 128 characters and each character is represented by one byte. When computers started to become globally popular, tech companies started to introduce new character encodings for different languages and for languages that have more than 256 characters, a simple 1 to 1 mapping was not possible. This leads to different problems such as sharing documents or browsing websites and a new Unicode standard that can handle most of the world’s writing systems was needed. UTF-8 was created to solve these problems. In UTF-8, not all characters are represented with 1 byte. Characters can be represented with 1 byte to 4 bytes.

In the following examples, we are using the ü character that takes 2 bytes.

Use the -b (--bytes) option to cut out a section of a line by specifying a byte position.

Select the 5th byte:

echo 'drüberspringen' | cut -b 5
b

Select the 5th, 9th and 13th bytes:

echo 'drüberspringen' | cut -b 5,9,13
bpg

Select the range from 1st to 5th byte:

echo 'drüberspringen' | cut -b 1-5
drüb

At the time of writing this article the version of cut bundled in GNU coreutils doesn’t have an option to cut by characters. When using the -c option cut behaves the same as when using the -b option.

Cut Examples

The cut command is usually used in combination with other commands through piping. Here are a few examples.

Get a list of all users

The output of the getent passwd command is passed to cut which prints the 1st filed using : as delimiter.

getent passwd | cut -d ':' -f1

View 10 most frequently used commands

In the following example cut is used to strip the first 8 bytes from each line of the history command output.

history | cut -c8- | sort | uniq -c | sort -rn | head

Conclusion

By now you should have a good understanding of how to use the Linux cut command. Although very useful, cut command has some limitations. It doesn’t support specifying more than one characters as a delimiter and it doesn’t support multiple decimeters.

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