tail

Select a number of data rows from the end (bottom) of the input data set, return the result as a new table.

Usage

gurita tail [-h] [NUM]

Arguments

Argument	Description	Reference
-h	display help for this command	help
NUM	the number of rows to select	number of rows

See also

Compare to the head command that returns rows from the start (top) of the data instead of the end.

Simple example

In the following document we assume the existence of an input file called example.csv that contains the following data (10 data rows and 1 heading row):

sepal_length,sepal_width,petal_length,petal_width,species
5.1,3.5,1.4,0.2,setosa
4.9,3.0,1.4,0.2,setosa
4.7,3.2,1.3,0.2,setosa
4.6,3.1,1.5,0.2,setosa
5.0,3.6,1.4,0.2,setosa
5.4,3.9,1.7,0.4,setosa
4.6,3.4,1.4,0.3,setosa
5.0,3.4,1.5,0.2,setosa
4.4,2.9,1.4,0.2,setosa
4.9,3.1,1.5,0.1,setosa

Select the last 5 rows from example.csv :

gurita tail 5 < example.csv

The output of the above command is:

sepal_length,sepal_width,petal_length,petal_width,species
5.4,3.9,1.7,0.4,setosa
4.6,3.4,1.4,0.3,setosa
5.0,3.4,1.5,0.2,setosa
4.4,2.9,1.4,0.2,setosa
4.9,3.1,1.5,0.1,setosa

Note that there are 5 data rows in the above result plus one header row.

The tail command returns a data set as its output, so it can be combined with other commands in a chain using the + operator.

For example the following command uses tail to select the last 5 rows from the input data and then uses head to select the first 3 rows from the last 5. The net result is that rows 6,7,8 (counting from 1) of the original data are returned.

gurita tail 5 + head 3 < example.csv

sepal_length,sepal_width,petal_length,petal_width,species
5.4,3.9,1.7,0.4,setosa
4.6,3.4,1.4,0.3,setosa
5.0,3.4,1.5,0.2,setosa

Getting help

The full set of command line arguments for tail can be obtained with the -h or --help arguments:

gurita tail -h

Specifying the number of rows to select

The tail command takes exactly one argument, an integer NUM.

• If NUM > 0, rows will be selected from the end (bottom) of the data. If NUM is greater than or equal to the number of rows in the data then the entire input data will be returned as the result.

• If NUM = 0, the result will be an empty data set.

• If NUM < 0, select all rows except the first NUM rows of the data. If NUM is greater than or equal to the number of rows in the data then the result will be an empty data set.

Select the first 1 rows from example.csv:

gurita tail 1 < example.csv

The output of the above command is:

sepal_length,sepal_width,petal_length,petal_width,species
4.9,3.1,1.5,0.1,setosa

Select all but the first 3 lines from example.csv. Note that this yields the last 7 data rows of the data because there are 10 data rows in total and the first 3 are removed.

gurita tail -3 < example.csv

The output of the above command is:

sepal_length,sepal_width,petal_length,petal_width,species
4.6,3.1,1.5,0.2,setosa
5.0,3.6,1.4,0.2,setosa
5.4,3.9,1.7,0.4,setosa
4.6,3.4,1.4,0.3,setosa
5.0,3.4,1.5,0.2,setosa
4.4,2.9,1.4,0.2,setosa
4.9,3.1,1.5,0.1,setosa