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====== BASH - Commands - cut - Cut using Fields ======

The cut command allows users to cut sections of a text very easily.

For this, we need to use both the d and the f flag of cut.

The d flag stands for delimiters and f for fields.

Delimiters are special characters that separate section of a text from others.

Common examples include ‘-‘, ‘:’, and ” ” (space).

----

===== Cut the First Section of Input Stream =====

<code bash>
echo "Let's cut this input stream section by section" | cut -d ' ' -f 1
</code>

The above cut command will cut the first section of text (“Let’s” in this case) from the input stream.

Note that the value to the delimiter flag -d is a single space.

----

===== Cut the First Section of a File =====

<code bash>
cut -d ':' -f 1 test.txt
</code>

Returns the first columns of each row inside the file.

The value provided to the delimiter flag was a colon because that’s how our file separates the columns.

----

===== Cut Specific Sections of the Input Stream =====

<code bash>
echo "Let's cut this input stream section by section" | cut -d ' ' -f 1,2,3
</code>

Displays only the first three field of the given input string.

It is done using a comma-separated array of field positions.

The output of this command will be ‘Let’s cut this‘.

----

===== Cut Specific Sections of a File =====

<code bash>
cut -d ':' -f 1,2,3 test.txt
</code>

This command will also provide the same sort of output as the previous command.

----

===== Cut Range of Fields from the Input Stream =====

<code bash>
echo "Let's cut this input stream section by section" | cut -d ' ' -f 1-5
</code>

Cuts the first five fields of the string and displays it in the terminal.

The apostrophes are required when space is used as the delimiter between multiple fields.

----

===== Cut Range of Fields from a File =====

<code bash>
cut -d ':' -f 1-3 test.txt
</code>

Cuts each of the first three columns of our text file and show it as the output.

The apostrophes aren’t mandatory for characters like – or :.

----

===== Cut Each Entry from a Specific Field and List them Alphabetically =====

<code bash>
cut -d ':' -f 1 test.txt | awk '{print $1}' | sort
</code>

List the result alphabetically sorted.

----

===== Cut Each Entry from a Field and List them in Alphabetically Reverse Order =====

<code bash>
cut -d ':' -f 1 test.txt | awk '{print $1}' | sort -r
</code>

Sorts the entries in a reverse manner.

----

===== Cut from a Fixed Field to the End of the Input Stream =====

<code bash>
echo "Let's cut this input stream section by section" | cut -d ' ' -f 2-
</code>

This cut command will cut starting from the second field to the end of the string.

It can be beneficial when you need to cut from a specified position until the end of the input.

You can change the value of -f while keeping the trailing – on for cutting from different fields.

----

===== Cut from a Fixed Field to the End of a File =====

<code bash>
cut -d ':' -f 2- test.txt
</code>

Start cutting from the specified field and go till the end of each line.

----

===== Cut a Specified Number of Columns Starting from the First One =====

<code bash>
echo "Let's cut this input stream section by section" | cut -d ' ' -f -5
</code>

Cuts the first five fields of the given input.

You need to add the preceding hyphen(-) else the output will not match your expectation.

-----

===== Cut Some Specified Columns of a File Starting from the First One =====

<code bash>
cut -d ':' -f -2 test.txt
</code>

This will start cutting the file file test.txt from the first column and terminate after it has finished cutting the second command.

----

===== Cut Multiple Fields of CSV Files =====

<code bash>
cut -d ',' -f 1,2 file.csv
</code>

The cut command will often prove to be a viable tool when you’re working with massive CSV documents.

The above command, for example, will cut the first two columns of a comma-separated CSV file called file.csv.

----

===== Cut Specific Fields of CSV Files and Sort them in Reverse Order =====

<code bash>
cut -d ',' -f 1,3,5 file.csv | sort -r
</code>

The above command will cut the first, third, and fifth columns of a comma-separated CSV file named file.csv and display the output in the reverse order.

----

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----

===== Field Cuts =====

==== Cut fields from a string, using a delimiter ====

<code bash>
cut -f 2- -d ':'
23:34:45:56
</code>

NOTE: -d specifies delimiter

returns:

<code bash>
34:45:56
</code>

----

==== Cut fields from a string, without specifying a delimiter ====

<code bash>
cut -f 2
er rt fg wd ji
</code>

returns:

<code bash>
er rt fg wd ji
</code>

NOTE: cut didn't find the delimiter (default is tab) so returns whole line.

----

==== Cut fields from a string, without specifying a delimiter; and prevent printing when delimiter not found ====

<code bash>
cut -f 2 -s
er rt fg wd ji    
</code>

NOTE: cut wont print as -s flag is used to prevent printing when delimiter not found.

----

==== Cut fields from a file, using a delimiter ====

<code bash>
cut -d: -f1 /etc/passwd >users.txt
</code>