1. A Guide to Unix Using Linux Fourth Edition
Chapter 9
Exploring the UNIX/Linux Utilities

2. Understanding UNIX/Linux Utilities
UNIX/Linux utilities are classified into:
File processing
System status
Networking
Communications
Security
Programming
Source code management
Miscellaneous
A Guide to Unix Using Linux, Fourth Edition

3. Classifying UNIX/Linux Utilities
Several categories
Network tasks
Programming tasks
File-processing utilities
A Guide to Unix Using Linux, Fourth Edition

4. Checking Hard Disk Usage
Basic strategies used to maintain adequate free space:
Be vigilant against running dangerously low on free space
Use df command
Watch for conspicuous consumption
Use du command
Follow a routine schedule for “garbage” collection and removal
Use a combination of find and rm commands
A Guide to Unix Using Linux, Fourth Edition

5. Using the df Utility
If entered without specifying file system, shows information for all mounted file systems
A Guide to Unix Using Linux, Fourth Edition

6. Using the df Utility (continued)
A Guide to Unix Using Linux, Fourth Edition

7. Using the du Utility
With no options, report is based on all file usage
Starts at current directory
By default, output is in number of 512-byte blocks
A Guide to Unix Using Linux, Fourth Edition

8. A Guide to Unix Using Linux, Fourth Edition

9. Using System Status Utilities
System status commands reflect system’s performance
You can redirect the output of these commands to a file
File can later be:
Printed
Forwarded to system administrator and system tune-up specialists
A Guide to Unix Using Linux, Fourth Edition

10. Using the top Command
A Guide to Unix Using Linux, Fourth Edition

11. Using the uptime Command
Example: use it to track how long system has been up since last problem requiring a reboot
A Guide to Unix Using Linux, Fourth Edition

12. Using the free Command
Swap space is disk space that acts like an extension of memory
A Guide to Unix Using Linux, Fourth Edition

13. Using the free Command (continued)
A Guide to Unix Using Linux, Fourth Edition

14. Forwarding top and free Output
You may forward output of top and free to a computer support person for analysis
Example:
top n 3 > topdata
cat topdata
A Guide to Unix Using Linux, Fourth Edition

15. Managing Processes
When you run a program, it starts one or more processes
Processes are identified through a unique number
Process id or PID
UNIX and Linux offer utilities to:
Manage how a program is run
Monitor processes
Kill processes
A Guide to Unix Using Linux, Fourth Edition

16. Running Processes in the Background
UNIX/Linux is a multitasking OS
You can run processes in the background
To run a process in background:
Append the & character
Example:
top&
A Guide to Unix Using Linux, Fourth Edition

17. Monitoring Processes
If used with no options, shows a list of processes associated with the current login session
A Guide to Unix Using Linux, Fourth Edition

18. Monitoring Processes (continued)
A Guide to Unix Using Linux, Fourth Edition

19. Killing Processes
System administrator may want to kill a user’s process because:
Associated program is malfunctioning
Associated program is using too many system resources
A user may want to kill a process that is running in the background
A Guide to Unix Using Linux, Fourth Edition

20. Using Networking Utilities
UNIX and Linux offer many utilities to accommodate a connection to the network
ifconfig
ping
traceroute
netstat
A Guide to Unix Using Linux, Fourth Edition

21. Using the ifconfig Utility
Internet Protocol (IP) is used to help ensure that information on a network goes to the right place
IP address uses a dotted decimal notation
Consists of four octets separated by periods
Identifies a computer/device and the network it is on
A Guide to Unix Using Linux, Fourth Edition

22. Using the ping Utility Examples: ping rbrown@xxx.com ping redhat.com
A Guide to Unix Using Linux, Fourth Edition

23. Using the traceroute Utility
Sample use:
To ensure your computer is connected and working
To ensure your network is working from point to point
A Guide to Unix Using Linux, Fourth Edition

24. Using the netstat Utility
Information provided by netstat includes:
Network protocol communications
Network connections established by host computer
Network routing information
Information about remotely logged computers (netstat –atn)
A Guide to Unix Using Linux, Fourth Edition

25. Software Development Process
Creation of source files (.c,.h,.cpp)
Compilation (e.g. *.c *.o) and linking
Running and testing programs
g++ and make

26. Development Tools Creation of source files (*.c, *.h, *.cpp)
Text editors
vi, nano
Compilation (*.o) and linking
Compilers
gcc, g++
g++ and make

27. Basic g++ Examples g++ hello.cpp g++ -o hello hello.cpp
compile hello.cpp
produce executable a.out
g++ -o hello hello.cpp
produce executable hello
g++ -o hello hello.cpp util.cpp
compile hello.cpp and util.cpp

28. Basic gcc Examples gcc hello.c gcc -o hello hello.c
compile hello.c
produce executable a.out
gcc -o hello hello.c
produce executable hello
gcc -o hello hello.c util.c
compile hello.c and util.c

29. gcc/ g++ Options -Wall -c -o <file> -g
compile source files, but do not link
output is an object file corresponding to source file
-o <file>
puts output in file called <file> -g
include debugging symbols in the output
to be used later by debugging program (gdb)
-Wall
display all warnings – program may still compile