Pt 2 Ch. 11 The Environment

Question 1

What knowledge allows us to use the environment to customize our shell experience?

Answer 1

Some programs look for values stored in the environment to adjust their behavior.

Question 2

The shell stores two basic types of data in the environment

Answer 2

1. environment vaiables 2. shell variables

Question 3

What’s the best way to view the enviornment?

Answer 3

prinenv | less or set | less

Question 4

How do set and printenv differ?

Answer 4

The set command shows both the shell and environment variables. Printenv shows only the latter

Question 5

What does printenv show us?

Answer 5

A list of environment variables and their values

Question 6

How can the printnenv command list the value of a specific variable?

Answer 6

printenv USER

me

Question 7

What one element of the environment does neither set nor printenv display?

Answer 7

aliases

Question 8

How do you see the aliases in the enivornment?

Answer 8

enter alias command without arguments

Question 9

The name of the display if we are running a graphical environment.
Usually this is “:0”, meaning the first display generated by the X
server.

Answer 9

Display

Question 10

The name of the program to be used for text editing.

Answer 10

EDITOR

Question 11

The name of the user’s default shell program.

Answer 11

SHELL

Question 12

The pathname of your home directory.

Answer 12

HOME

Question 13

Defines the character set and collation order of your language.

Answer 13

LANG

Question 14

The previous working directory.

Answer 14

OLDPWD

Question 15

The name of the program to be used for paging output. This is often
set to /usr/bin/less.

Answer 15

PAGER

Question 16

A colon-separated list of directories that are searched when we enter
the name of a executable program

Answer 16

PATH

Question 17

This stands for “prompt string 1.” This defines the contents of the
shell prompt. As we will later see, this can be extensively
customized.

Answer 17

PS1

Question 18

This stands for “prompt string 1.” This defines the contents of the
shell prompt. As we will later see, this can be extensively
customized.

Answer 18

PS1

Question 19

The current working directory.

Answer 19

PWD

Question 20

The name of your terminal type. Unix-like systems support many
terminal protocols; this variable sets the protocol to be used with
your terminal emulator.

Answer 20

TERM

Question 21

Specifies your time zone. Most Unix-like systems maintain the
computer’s internal clock in Coordinated Universal Time (UTC)
and then display the local time by applying an offset specified by
this variable.

Answer 21

TZ

Question 22

USER

Answer 22

Your username

Question 23

What do startup files do

Answer 23

They define the default environment shared by all users. When we log on to the system, the bash program starts, and reads these series of configurations scripts.

Question 24

A session is one in which we are prompted for
our username and password. This happens when we start a virtual console session,
for example.

Answer 24

A login shell session

Question 25

this session typically occurs when we launch a terminal session in the GUI. Login shells read one or more startup files as sh

Answer 25

A non-login shell session

Question 26

A global configuration script that applies to all users

Answer 26

/etc/profile

Question 27

A user's personal startup file. This can be used to extend | or override settings in the global configuration script.

Answer 27

~/.bash_profile

Question 28

If ~/.bash_profile is not found, bash attempts to | read this script.

Answer 28

~/.bash_login

Question 29

If neither ~/.bash_profile nor ~/.bash_login | is found, bash attempts to read this file. T

Answer 29

~/.profile

Question 30

A global configuration script that applies to all users.

Answer 30

/etc/bash.bashrc

Question 31

A user's personal startup file. It can be used to extend or | override settings in the global configuration script.

Answer 31

~/.bashrc

Question 32

In addition to reading startup files non-login shells inherit

Answer 32

the environments from their parent process, usually a login shell

Question 33

Using this technique, we can append text to the end of a variable's contents.

Answer 33

``` [me@linuxbox ~]$ foo="This is some " [me@linuxbox ~]$ echo $foo This is some [me@linuxbox ~]$ foo=$foo"text." [me@linuxbox ~]$ echo $foo This is some text. ```

Question 34

The PATH variable is often (but not always, depending on the distribution) set by the / etc/profile startup file with this code:

Answer 34

PATH=$PATH:$HOME/bin

Question 35

export PATH

Answer 35

the export command tells the shell to make the contents of PATH available to child processes of this shell

Question 36

What changes should be placed in .bash_profile? or .profile?

Answer 36

if you are adding directories to your PATH or defining additional environment variables

Question 37

what changes belong in .bashrc

Answer 37

any changes besides adding directories to your path or defining additional environment variables.

Question 38

What allows us to modify the environment?

Answer 38

Knowing where the startup files are and what they contain

Question 39

What program is used to edit the shell's startup files, as well as most of the other configuration files on the system

Answer 39

Text editor

Question 40

Two basic categories of Text Editors

Answer 40

Graphical and text based.

Question 41

How are text editors invoked from the command line?

Answer 41

By typing the name of the editor followed by the name of the file we want to edit

Question 42

What's a safe computing practice whenever we edit an important configuration file?

Answer 42

Create a backup of the file first

Question 43

How do we exist a text editor program?

Answer 43

Ctrl-X

Question 44

How do we save work in a text editor program

Answer 44

ctrl-o

Question 45

What happens if you add a # symbol in front of valid alias definitions in text editor?

Answer 45

You can deactivate a configuration line while preserving the information it contains

Question 46

what section of the bash man page covers the bash startup files

Answer 46

INVOCATION