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

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

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

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

A Guide to Unix Using Linux, Fourth Edition

A Guide to Unix Using Linux, Fourth Edition

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

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

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

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

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

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

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

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

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

A Guide to Unix Using Linux, Fourth Edition

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

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

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

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

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

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

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

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

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

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

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

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

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

Checking the Spelling of a Document (continued) A Guide to Unix Using Linux, Fourth Edition

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

Using the dump Command A Guide to Unix Using Linux, Fourth Edition

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

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

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

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

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

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

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

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

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

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

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

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

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

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