shells

Question 1

name some shells

Answer 1

Bash, Dash, KornShell, tcsh, Z shell

Question 2

display current shell on Cent OS

Answer 2

echo $SHELL

Question 3

display current shell on Ubuntu

Answer 3

uname -a to provide all system information such as processor type, OS name

Question 4

what does the type command do

Answer 4

lets you know if a command is internal or external

Question 5

environmental variables

Answer 5

track specific system info, such as name of user logged onto shell, default home dir, search path shell uses to find exe programs

Question 6

set

Answer 6

displays active environmental variables

Question 7

$PATH

Answer 7

colon separated list of directories to search for commands

Question 8

PS1

Answer 8

shell prompt

Question 9

subshell / childshell

Answer 9

created when you perform certain tasks, such as running a shell script.

Question 10

echo $SHLVL

Answer 10

any level higher than 1 indicates you are in a subshell

Question 11

man

Answer 11

documentation regarding a command’s purpose, various options, syntax, etc

Question 12

history

Answer 12

view recent commands

Question 13

how to reexecute commands in command history?

Answer 13

put an exclamation mark prior to the number