cut Command in Linux

The cut command in Linux is used to extract specific parts of each line from a file or input. You can extract data based on byte position, character position, or fields separated by a delimiter. It is mainly used to select and display required columns from text files.

• Extracts specific bytes, characters, or fields from each line
• Works with delimiters like space, tab, or custom characters
• Reads input from a file or standard input (stdin)
• Commonly used for text processing and data filtering

Example 1: Running cut Without Any Option

If you run the cut command without specifying any option, it results in an error.

• The cut command always needs what to extract
• You must use options like -b, -c, or -f

cat sample.txt

cut sample.txt

• The cut command always needs what to extract
• You must use options like -b, -c, or -f

Example 2: Extract Fields Using Space as Delimiter

This example extracts the 2nd and 3rd fields from each line using space as the delimiter.

cut -d " " -f 2 sample.txt

• -d " ": Sets space as the field delimiter.
• -f 2: Extracts the second field from each line.
• Only selected fields are displayed on the terminal

Extracting fields using space as delimiter

Example 3: Extract Multiple Fields

You can extract more than one field at the same time.

cut -d " " -f 1,2 sample.txt

• -f 1,2: extracts the 1st and 2nd fields from each line of sample.txt, using a space (" ") as the delimiter.
• It displays only the selected columns (e.g., state and capital names) from the input file.

Extracting multiple fields

Syntax

cut OPTION... [FILE]..

• OPTION: Specifies how the cut command behaves. such as: bytes (-b) characters (-c) fields (-f)
• FILE: The input file from which data is extracted. If no file is provided, cut reads input from standard input (stdin).

Note: At least one option (-b, -c, or -f) is mandatory

Options Available in cut Command

The cut command provides several options to extract specific parts of each line. Each option focuses on how the data is selected.

1. -b, --bytes: Extract by Byte Position

The -b option is used to extract specific byte positions from each line of a file. It is useful when working with fixed-width data or files where each byte position has a meaning.

Bytes can be specified as:

• Individual positions (e.g., 1,3,5)
• Ranges (e.g., 1-4)
• From start or till end of the line

Example 1: Extract Specific Bytes

It will extract and display the 1st, 2nd, and 3rd bytes (characters) from each line of the state.txt file

cut -b 1,2,3 state.txt

• -b 1,2,3 selects the 1st, 2nd, and 3rd bytes
• These bytes are extracted from each line
• Only the selected bytes are printed on the terminal

Extract Specific Bytes

Example 2: Extract Bytes Using Ranges

It will extract characters from positions 1 to 3, and then from 5 to 7, from each line of the file named state.txt

cut -b 1-3,5-7 state.txt

• 1-3 extracts bytes from position 1 to 3
• 5-7 extracts bytes from position 5 to 7
• Both ranges are applied to each line of the file

list with range

Example 3: Extract Bytes from Beginning to End of Line

This example extracts all bytes starting from the first byte till the end.

cut -b 1- state.txt

• 1- means from byte 1 to the last byte
• Entire line is printed as-is

special form with -b option

Example 4: Extract Bytes from Beginning up to a Specific Position

This example extracts bytes from the first byte up to the third byte.

cut -b -3 state.txt

• -3 means extract from byte 1 to byte 3
• Starting position is automatically assumed as 1

special form -b option

2. -c, --characters: Extract Output by Character Position

-c (column): The -c option in the cut command Unix extracts characters. You can specify a list of character positions with commas or a range with a hyphen (-).

Tabs and backspaces are treated as single characters, and a valid character list is required to avoid errors.

• Character positions start from 1
• Tabs and spaces are treated as single characters
• Recommended for text-based files

Syntax:

cut -c [(k)-(n)/(k),(n)/(n)] filename

Here, k denotes the starting position of the character and n denotes the ending position of the character in each line, if k and n are separated by "-" otherwise they are only the position of character in each line from the file taken as an input.

Example 1: Extract Specific Characters from Each Line

It will extract and display the characters at positions 2, 5, and 7 from each line of the file named state.txt

cut -c 2,5,7 state.txt

• -c 2,5,7 selects characters at positions 2, 5, and 7
• These characters are printed from each line
• All other characters are ignored

Extract specific characters

This cut in Unix command prints the 2nd, 5th, and 7th characters from each line.

Example 2: Extract a Range of Characters

It extracts and displays the first 7 characters from each line of the file named state.txt.

cut -c 1-7 state.txt

• 1-7 selects characters from position 1 to 7
• Output includes only the selected portion of each line

Extract first seven characters

Above cut command prints first seven characters of each line from the file. Cut uses a special form for selecting characters from beginning upto the end of the line:

Example 3: Extract Characters from Beginning to End of Line

It extracts and displays the first character of each line from the file named state.txt.

cut -c 1- state.txt

• 1- means from character 1 to the last character
• Entire line is displayed

selecting characters from beginning to end of line using -c option

Above command prints starting from first character to end. Here in command only starting position is specified and the ending position is omitted.

Example 4: Extract Characters from Beginning up to a Specific Position

This example extracts characters from the first character up to the fifth character.

cut -c -5 state.txt

• -5 extracts characters from position 1 to 5
• Starting position is assumed automatically

selecting characters from beginning to end of line using -c option

Above command prints starting position to the fifth character. Here the starting position is omitted and the ending position is specified.

3. -f, --fields: Extract Output by Fields

The -f option is used to extract specific fields (columns) from each line of a file. Fields are groups of characters separated by a delimiter. By default, the delimiter is TAB, but you can use the -d option to specify other delimiters like space, comma, or colon.

Note: Space is not considered as delimiter in UNIX.

Syntax:

cut -d "delimiter" -f (field number) file.txt

Example 1: Attempt to Extract a Field Using Default Delimiter

This example shows what happens when you try to extract a field without defining a delimiter. It helps users understand why specifying -d is important, otherwise the command may not work as expected.

cut -f 1 state.txt

• Default delimiter is TAB
• Since state.txt is space-separated, no field split occurs
• Entire line is printed instead of a single field

Extract first field using -f option

Note: Always specify -d when your file is not tab-separated.

Example 2: Extract the First Field Using Space as Delimiter

This example extracts only the first column (state names) from a space-separated file. Useful when you want one specific column from structured text.

If `-d` option is used then it considered space as a field separator or delimiter:

cut -d " " -f 1 state.txt

• -d " ": sets space as the field delimiter
• -f 1: selects the first field from each line
• Only the required column is displayed

space as a field separator or delimiter

Example 3: Extract a Continuous Range of Fields

This example demonstrates how to extract a group of consecutive fields. Helpful when data spans across multiple columns that belong together.

Command prints field from first to fourth of each line from the file.

cut -d " " -f 1-4 state.txt

• -d " ": sets space as the delimiter.

Command prints field from first to fourth

4. --complement: Invert the Selected Fields or Characters

This option is used to reverse the selection made by other options such as -f or -c. Instead of printing the selected fields or characters, it prints everything except the specified ones.

• Must be used with another selection option (-f or -c)
• Cannot be used alone
• Helpful for excluding unwanted data instead of selecting required data

Example 1: Remove the First Field from Each Line

This example removes the first column from a space-separated file and prints the remaining fields. It helps when the first column is not required for further processing.

cut --complement -d " " -f 1 state.txt

• -d " ": sets space as the delimiter.
• -f 1: selects the first field.
• --complement: tells cut to exclude the selected field.
• All fields except the first one are printed.

--complement

Example 2: Remove a Specific Character Position

This example removes a specific character position from each line. It is useful when you want to delete fixed-position characters such as formatting symbols.

cut --complement -c 5 state.txt

• -c 5: selects the 5th character from each line.
• --complement: excludes that character.
• All characters except the 5th one are printed.

--complement

5. --output-delimiter: Change the Output Field Separator

The --output-delimiter option is used to change the delimiter used in the output. By default, the output delimiter is the same as the input delimiter specified using -d.

• Works only when using the -f option
• Does not modify the input file
• Affects only how data is displayed on the terminal
• Very useful for data formatting in scripts

Example: Change Output Delimiter to a Custom Symbol

This example changes the output delimiter from space to % while extracting selected fields. It helps when you want the output in a specific format.

cut -d " " -f 1,2 state.txt --output-delimiter='%'

• -d " ": tells the cut command that fields in the file are separated by spaces.
• -f 1,2: selects the first and second fields from each line.
• By default, these two fields would be printed with a space between them.
• --output-delimiter='%': changes this space into a percent (%) symbol in the output.
• The original file remains unchanged, only the displayed output is formatted differently.

6. Display Version (--version) Using cut Command

--version: This option is used to display the version of cut which is currently running on your system.

cut --version

display version of cut command

Real-World Use Cases

The cut command is often combined with other Linux commands using pipes (|). This allows you to extract only the required part of data and then process it further.

1. Extract a Column and Sort It

This example extracts the first field (state names) from a space-separated file and then sorts them in reverse order.

cat state.txt | cut -d ' ' -f 1 | sort -r

• cat state.txt: displays the content of the file.
• cut -d " " -f 1: extracts only the first field (state names).
• sort -r: sorts the extracted names in reverse alphabetical order.
• The final output shows only sorted state names.

using tail with pipe (|) in cut command

2. Extract Specific Fields from First Few Lines of a File

This example extracts data from only the first few lines of a file and saves the result to another file. Helpful when previewing or processing large files.

cat state.txt | head -n 3 | cut -d ' ' -f 1 > list.txt

• cat state.txt: sends file content to the pipeline.
• head -n 3: limits the output to the first three lines.
• cut -d " " -f 1: extracts the first field from those lines.
• >: redirects the output into list.txt.

cat list.txt

redirecting output in different file