The Saigon CTT
The Linux Shell and
BASH Scripting
The Saigon CTT
Objectives
Objectives
Identify differrent Linux shell environments

Understand the redirection of input

Understand and utilize command substitution

Write and configure BASH script using
variables, flow controls interactive input,
functions, arithmetic and arrays
The Saigon CTT
Example of Script
Example of Script
$ more example_script
#!/bin/bash
/usr/bin/nmbd -D
/usr/bin/smbd -D

Shell Environment Customize
Shell Environment Customize

bash config files :
•
/etc/profile
•
~/.bash_profile, ~/.bash_login,
~/.profile, ..

Default environment variables : PS1, PS2,
HOME, LOGNAME, SHELL, PATH,
PAGER, LPDEST, PWD, DISPLAY,
MAIL, ..

set, unset, export, … commands
The Saigon CTT
Using the
Using the
bash
bashshell
shell

Alt+Fn


Pipe (|)
#ls –l *.JPG | tee file_name
#ls –al /root | grep error >error_file

Back ticks (`) or “$()”
# which passwd
/usr/bin/passwd
# ls –l `which passwd`
-r-sr-xr-x 1 root root 13476 Aug 7 /usr/bin/passwd
The Saigon CTT
Redirecting Input and Output
Redirecting Input and Output

Sometimes the output of a command is a
list (ex: ls) and we wish to execute
another command on each of the entries,
use xargs
#ls | xargs grep README
Do Not use :
#ls –al | xarg grep README
The Saigon CTT
Background jobs
Background jobs