1. Shell Commands
Using BASH
Copyright © 2017 Curt Hill

2. Introduction
The standard UNIX 7 shell (sh) was written by Stephen Bourne
Bourne Again SHell is the GNU rewrite of the original sh
Written by Brian Fox
Meant to be compatible with the sh
Also influenced by the Korn shell and the C shell
This presentation looks at some of these features
Copyright © 2017 Curt Hill

3. Before This We have looked at several standard commands
File manipulation and the like
Now we look at several other features
Redirection
Brace expansion
Process management
Copyright © 2017 Curt Hill

4. Redirection > < 2> &> | Redirect standard output
Redirect standard input
2>
Redirect standard error
&>
Both out and err to same file |
Pipe standard output to standard input of the next program
Copyright © 2017 Curt Hill

5. Brace Expansion Items in braces are expanded into separate pieces
Thus a{p,g,l}e will become ape age ale
This may be used for files or parameters
Copyright © 2017 Curt Hill

6. More You may also use two dot ellipsis to show ranges
{a..d} produces a b c d
A triple is like a for loop with start..end..incr
{ } produces
{ } also produces
Only the last one needs to be a digit
{a..i..2} produces a c e g i
Copyright © 2017 Curt Hill

7. Examples ls –l *.{c,h,cpp,cxx} ls file{1..4}.txt
This will show most C/C++ sources
ls file{1..4}.txt
This will show only the series file1.txt, file2.txt, file3.txt and file4.txt
Copyright © 2017 Curt Hill

8. Process Management Normally, we execute commands successfully
This is done by separating commands by a semicolon
This can also be done by putting on separate lines
You may also get the programs to run simultaneously by separating with an ampersand
X & Y
Copyright © 2017 Curt Hill

9. Process IDs When the ampersand is used we force a new process
This is shown with a Process ID (PID) and this is usually shown in brackets
The kill command will stop a process by giving the Process ID
Copyright © 2017 Curt Hill

10. Startup Scripts Bash may execute scripts by default
When it starts at login it attempts to execute
/etc/profile
Next it tries to execute
.bash_profile, .bash_login and .profile from the current login directory
The first one it finds it executes
It attempts to execute .bash_logout when it exits
Copyright © 2017 Curt Hill

11. Finally
All of these features are characteristic of Bash in interactive mode
Next we need to consider scripting
Copyright © 2017 Curt Hill