Chapter $8,$ Lab $3$: History, Aliases, and Functions

$(25$ Minutes$)$

Learning Objectives and Outcomes

In this lab you will learn to use the bash history feature to view and repeat previous commands. You will also experiment with

aliases that can translate one $($usually shorter$)$ command into another, and functions that can perform a series of commands.

Reading

Read the sections on history $($Sobell$),$ using exclamation points to reference events $($Sobell$,$ pages $331-332),$ aliases $($Sobell$,$

pages $342-345),$ and functions $($Sobell$).$

Procedure

Type the following commands:

$ head $/$etc$/$services

$$1\frac{s}{e}tc$

$ who

$ date

Use the up arrow key to repeat a display of the last command.

Use history and tail $($Sobell$)$ to list the $10$ most recent commands you issued.

It is okay if you have only the preceding five commands in your history list.

Read "Using an Exclamation Point $(!)$ to Reference Events" in Sobell$1.$

a$.$

Repeat the ls $/$etc command using that command's event number $($Sobell$).$

b$.$

Repeat the date command by specifying it as the $n$ th preceding command.

Be careful: Each time you issue a command, the relative number of each preceding command changes.

You might want to give another history command before you proceed.

c$.$

Repeat the previous command using $!.$

Create an alias $($Sobell$)$ that translates the command $d$ into date.

Make sure the new alias works.

Display the alias.

Create an alias that translates the command ls into ls $-l.$ Test the alias.

Give a ls command that does not use the alias.

Remove the alias and show that the alias no longer exists.

Where would you define an alias so that it is available each time you log in$?$

Write a one$-$line function $($Sobell$,$ page $346)$ named welcome that displays Welcome to my computer.

Demonstrate that the function works.

Write a function named long that displays the date and a long listing of the working directory. Demonstrate that the

function works.

Where would you define a function so that it is available each time you log in$?$