Bash cut Command - Remove Sections from Lines

Using the cut Command

The cut command is used to remove sections from each line of files.

It's a useful tool for extracting specific fields of data from a file or output stream.

All examples below use the example_data.txt file:

Kai 	Refsnes	30,Norway
Robin	Smith	25,Denmark
Sienna	Davis	40,Germany

Basic Usage

To extract the first field of a file, use cut -f1 filename:

cut -f1 example_data.txt
Kai
Robin
Sienna

By default, cut uses a tab as the delimiter.

Options

The cut command has options to change how it works:

• -d - Choose what separates the fields
• -f - Select specific fields to display
• --complement - Show all fields except the selected ones

Specify a Delimiter

The -d option allows you to choose what separates the fields.

cut -d',' -f1 example_data.txt
Kai     Refsnes 30
Robin   Smith   25
Sienna  Davis   40

Select Specific Fields

The -f option allows you to select specific fields to display.

cut -f1-2 example_data.txt
Kai     Refsnes
Robin   Smith
Sienna  Davis

Show Complement

The --complement option allows you to show all fields except the selected ones.

cut --complement -f1 example_data.txt
Refsnes 30,Norway
Smith   25,Denmark
Davis   40,Germany

Advanced Field Extraction

Cut can perform advanced field extraction tasks.

For example, cut -d' ' -f2-3 example_data.txt extracts fields 2 through 3 from the file.

cut -f2-3 example_data.txt
Refsnes 30,Norway
Smith   25,Denmark
Davis   40,Germany

Common Errors and Troubleshooting

When using cut, you might encounter errors such as:

• "cut: delimiter must be a single character" - Ensure the delimiter is correctly specified.
• "cut: fields and positions are numbered from 1" - Remember that field and position numbering starts at 1.

Debugging tips include checking the delimiter and field specifications to ensure they match the file's format.