one

Question 1

Starting off with a Sha-Bang

Answer 1

#!
tells the script to be fed to a specific interpreter

Question 2

If the sha-bang is incorrect

Answer 2

Probably I will get “Command not found”

Question 3

what will #!/bin/sh invoke

Answer 3

It will invoke the default shell interpreter, namely, bash

Question 4

How to interpret a file manually using bash?

Answer 4

bash filename

Question 5

Find out the current shell name

Answer 5

cat /etc/shells
echo $SHELL
ps $$
ps -p $$

Question 6

How to get manuals of commands

Answer 6

man command

command –help

Question 7

How to find out a command is a built-in or an external binary file

Answer 7

type -a

Question 8

bash startup scripts

Answer 8

script of commands executed at login to set up environment

Question 9

login shell

Answer 9

when login shell is started:
1  /etc/profile runs first
2 /etc/profile.d
3 $HOME/.bash_profile which will cass $HOME/.bashrc
   $HOME/.bash_login
   $HOME/.profile

Question 10

logout shell

Answer 10

If log out, it will call $HOME/.bash_logout

Question 11

find out available binary packages shell list

Answer 11

yum search shell

apt-cache search shell

Question 12

Display the full path of shell commands

Answer 12

which command

Question 13

multiple line comment

Question 14

remove permission

Answer 14

chmod ugo= filename

Question 15

debug bash script

Answer 15

bash -x scriptname

Question 16

How to use set to turn on debug mode or turn off debug mode

Answer 16

set -x turn on the debug mode

set +x turn off the debug mode

Question 17

How to check the syntax error in the bash script

Answer 17

set -n Read the script and check the syntax but don’t output it

Question 18

display the input lines and show if the line is implemented and show the result

Answer 18

set -v or bash -v

Question 19

set the bash debug in the bash script without set

Answer 19

!/bin/bash -xv

Question 20

enable the backslash in echo

Answer 20

echo -e

while disable it by echo -E

Question 21

view system variables

Answer 21

set
env
printenv

Question 22

check bash version

Answer 22

echo $BASH_VERSION

Question 23

how to initialize the environmental variables

Answer 23

write them in the ~/.bash_profile

Question 24

can we use like $(HOME)

Answer 24

no, the right answer is ${HOME}