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--- bash:cut:cut_using_fields [2020/07/15 09:30] – external edit 127.0.0.1
+++ bash:cut:cut_using_fields [2021/01/26 16:05] (current) – removed peter
@@ Line 1: / Line 1: @@
-====== BASH - 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.
-----
-*************************************************************************************************************************************************
-*************************************************************************************************************************************************
-*************************************************************************************************************************************************
-*************************************************************************************************************************************************
-----
-===== Field Cuts =====
-==== Cut fields from a string, using a delimiter ====
-<code bash>
-cut -f 2- -d ':'
-:34:45:56
-</code>
-NOTE: -d specifies delimiter
-returns:
-<code bash>
-: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>