Transcript TuneUp e utilities

A Guide to Unix Using Linux
Fourth Edition
Chapter 8
Exploring the UNIX/Linux Utilities
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
2
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 e-mail
• Use basic network commands and utilities
A Guide to Unix Using Linux, Fourth Edition
3
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
4
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
5
A Guide to Unix Using Linux, Fourth Edition
6
A Guide to Unix Using Linux, Fourth Edition
7
Classifying UNIX/Linux Utilities
(continued)
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
Using the dd Command
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
A Guide to Unix Using Linux, Fourth Edition
14
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
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
A Guide to Unix Using Linux, Fourth Edition
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 tuneup 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
A Guide to Unix Using Linux, Fourth Edition
22
Using the free Command
• Swap space is disk space that acts like an
extension of memory
A Guide to Unix Using Linux, Fourth Edition
23
Using the free Command (continued)
A Guide to Unix Using Linux, Fourth Edition
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&
A Guide to Unix Using Linux, Fourth Edition
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
A Guide to Unix Using Linux, Fourth Edition
31
Checking the Spelling of a Document
(continued)
A Guide to Unix Using Linux, Fourth Edition
32
Comparing Files
• If the contents are identical, there is no output
• Otherwise, output specifies first byte (character)
that is different between the files
A Guide to Unix Using Linux, Fourth Edition
33
Formatting Text in UNIX/Linux
A Guide to Unix Using Linux, Fourth Edition
34
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
A Guide to Unix Using Linux, Fourth Edition
35
Using the dump Command
A Guide to Unix Using Linux, Fourth Edition
36
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
37
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
38
Using mail to Send Mail (continued)
A Guide to Unix Using Linux, Fourth Edition
39
Using mail to Send Mail (continued)
A Guide to Unix Using Linux, Fourth Edition
40
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
41
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
42
Using the ping Utility
• Examples:
– ping [email protected]
– ping redhat.com
A Guide to Unix Using Linux, Fourth Edition
43
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
44
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
A Guide to Unix Using Linux, Fourth Edition
45
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
A Guide to Unix Using Linux, Fourth Edition
46
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 192.168.0.72(ro) 192.168.0.84(ro)
/home/mpalmer/docs 192.168.0.72(rw) 192.168.0.41(rw)
A Guide to Unix Using Linux, Fourth Edition
47
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
A Guide to Unix Using Linux, Fourth Edition
48
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
49
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
50
Command Summary
A Guide to Unix Using Linux, Fourth Edition
51