1. A Guide to Unix Using Linux Fourth Edition
Chapter 8
Exploring the UNIX/Linux Utilities

2. Objectives
Understand many of the UNIX/Linux utilities that are available and how they are classified
Use the dd utility to copy and convert files
Monitor hard disk usage
Use system status utilities
Monitor and manage processes
Check the spelling of text in a document
A Guide to Unix Using Linux, Fourth Edition

3. Objectives (continued)
Use the cmp command to compare the contents of two files
Format text to create and use a man page
Use the dump command to back up a system
Send and receive
Use basic network commands and utilities
A Guide to Unix Using Linux, Fourth Edition

4. 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

5. Classifying UNIX/Linux Utilities
Several categories
Network tasks
Programming tasks
File-processing utilities
Make up the largest category
Display and manipulate files
A Guide to Unix Using Linux, Fourth Edition

6. A Guide to Unix Using Linux, Fourth Edition

7. A Guide to Unix Using Linux, Fourth Edition

8. Classifying UNIX/Linux Utilities (continued)
A Guide to Unix Using Linux, Fourth Edition

9. Classifying UNIX/Linux Utilities (continued)
A Guide to Unix Using Linux, Fourth Edition

10. Classifying UNIX/Linux Utilities (continued)
A Guide to Unix Using Linux, Fourth Edition

11. Classifying UNIX/Linux Utilities (continued)
A Guide to Unix Using Linux, Fourth Edition

12. Classifying UNIX/Linux Utilities (continued)
A Guide to Unix Using Linux, Fourth Edition

13. 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
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14. Using the df Utility
If entered without specifying file system, shows information for all mounted file systems
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15. Using the df Utility (continued)
A Guide to Unix Using Linux, Fourth Edition

16. 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
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17. A Guide to Unix Using Linux, Fourth Edition

18. Removing Garbage Files
Garbage files are temporary files that lose their usefulness after several days
Remove to free space
Example: core files, compilation output
Core file: created when executing program attempts to do something illegal
Example: accessing another user’s memory
Use find and rm to find and remove garbage files:
find . "(" -name a.out -o -name core ")" -exec rm {} \;
A Guide to Unix Using Linux, Fourth Edition

19. 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

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

21. Using the uptime Command
Example: use it to track how long system has been up since last problem requiring a reboot
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22. Using the free Command
Swap space is disk space that acts like an extension of memory
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23. Using the free Command (continued)
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24. 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
lpr topdata
A Guide to Unix Using Linux, Fourth Edition

25. 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

26. 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&
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27. 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

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

29. 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

30. Checking the Spelling of a Document
ispell
Scans a text document
Displays errors on screen
Suggests other words with similar spellings as replacements for unrecognized words
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31. Checking the Spelling of a Document (continued)
A Guide to Unix Using Linux, Fourth Edition

32. Archiving and Backing Up Files
Good practice to periodically archive or back up files
You can back up files to:
CD, DVD, tape, or another removable medium
For backup to CD/DVD, consider using a GUI tool
Example: GNOME CD/DVD Creator GUI software
Part of Nautilus
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33. Using the dump Command
A Guide to Unix Using Linux, Fourth Edition

34. Using the restore Command
Restores from a backup medium created via dump
By default, copies back to current working directory
Example: restore -r -f /dev/st0
A Guide to Unix Using Linux, Fourth Edition

35. Using mail to Send Mail Press Ctrl+d to exit the text mode
To leave the mail utility, type q and press Enter
A Guide to Unix Using Linux, Fourth Edition

36. Using mail to Send Mail (continued)
A Guide to Unix Using Linux, Fourth Edition

37. Using mail to Send Mail (continued)
A Guide to Unix Using Linux, Fourth Edition

38. 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

39. 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

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

41. 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

42. 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
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43. Sharing Resources Using Network File System
Network File System (NFS): used for resource sharing over a network
Once partition is mounted, access is transparent
mount bluefin:/home/mpalmer/shared /mnt/shared
Three versions typically supported:
NFSv2, NFSv3, and NFSv4
Client and host communicate via RPCs
RPC: Remote Procedure Call
Portmap service:
Handles RPC request to mount a partition
Makes computer act like a server for NFS file access
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44. Sharing Resources Using Network File System (continued)
To start a service, use service command
service portmap
NFS security handled through entries in:
/etc/hosts.allow, /etc/hosts.deny, and /etc/exports
/home/mpalmer/shared (ro) (ro)
/home/mpalmer/docs (rw) (rw)
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45. Accessing Microsoft Windows Systems Through Samba
Samba: utility that uses the SMB protocol
Server Message Block (SMB) is used by Windows systems for sharing folders and printers
Typical configuration file:
/etc/samba/smb.conf file
Some ways to access Windows shared drives:
Network Servers  Windows Network
Computer  More Applications  Network Servers File Browser  Windows Network
K menu  KNOPPIX  Utilities  Samba Network Neighborhood
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46. Summary Some useful utility programs are:
dd, df, and du for converting files, checking free space, and checking disk usage, respectively
find and rm can be used together to remove garbage files
top and free provide detailed views of system internals
uptime shows how long a system has been up
ps and kill to display and kill processes
ispell to check for spelling errors in a file
nroff, troff, and groff for formatting output
A Guide to Unix Using Linux, Fourth Edition

47. Summary (continued) Other useful utility programs are:
dump and restore to archive and restore backups
mail to send and retrieve mail
ifconfig, ping, traceroute, and netstat for viewing information about the network connection and for troubleshooting the connection
Services for sharing resources over network:
Network File System (NFS) to access resources in another UNIX/Linux computer
Samba to access resources in a Windows computer
A Guide to Unix Using Linux, Fourth Edition