Linux Module 1
Transcript of Linux Module 1
-
8/7/2019 Linux Module 1
1/305
11
LinuxLinuxFundamental AdministrationFundamental Administration
in a Linux environmentin a Linux environment
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
2/305
22
Module 1Module 1Role of a sys adminRole of a sys admin
System DocumentationSystem DocumentationHelpHelp
File system layoutFile system layout4/6/20114/6/2011
-
8/7/2019 Linux Module 1
3/305
33
File SystemFile System
DirectorysDirectorys Locations for files andLocations for files anddirectories.directories.
SubdirectorysSubdirectorys-- A directory that isA directory that isbelow a directory.below a directory.
DocumentsDocuments ASCII, ASCII,
ApplicationsApplications databases, worddatabases, wordprocessors, spreadsheetsprocessors, spreadsheets
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
4/305
44
File System: UnixFile System: Unix
Unix File Str ct re
bin sbin lib
bin sbin etc
local
sr dev etc
ser ser2 ser3
home lib var boot bin
floppy cdrom
mnt sbin root proc
Root (/)
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
5/305
55
Filesystem Hie y St ndardFilesystem Hierarchy Standard
1993 Linux community formed a1993 Linux community formed aproject too standardize theproject too standardize thefilesystem layout for all generalfilesystem layout for all general
purpose Linux distributionspurpose Linux distributions Known as the Linux FilesystemKnown as the Linux Filesystem
Standard but later renamed to theStandard but later renamed to the
Filesystem Hierarchy StandardFilesystem Hierarchy Standard FHS defines two categories of dataFHS defines two categories of data
use: Data Sharing and Datause: Data Sharing and DataModificationModification
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
6/305
66
Data SharingData Sharing
ShareableShareable -- Can be used by multiple hostCan be used by multiple hostsystems on a network. These files containsystems on a network. These files containgeneralgeneral--purpose information such as userpurpose information such as user
datafiles, executables and commondatafiles, executables and commonconfiguration filesconfiguration files
NonNon--shareableshareable -- Data is not shareableData is not shareablewhen it is linked to a specific host. For, awhen it is linked to a specific host. For, aunique configuration file such as theunique configuration file such as thepasswd file and system logspasswd file and system logs
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
7/305
77
DataModi icationDataModi ication
VariableVariable -- Data is considered variableData is considered variablewhen it changes by natural andwhen it changes by natural and
frequentfrequentprocesses(/var/log/messages)processes(/var/log/messages)
StaticStatic -- This data is left alone for theThis data is left alone for themost part remaining the same frommost part remaining the same from
day to day or even year to year.day to day or even year to year.
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
8/305
88
FHS Data Ty esFHS Data Ty es
Sharable Non-SharableStatic /usr
/usr/local
/etc
/bootVariable /var/mail
/home/var/log/proc
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
9/305
99
The root FilesystemThe root Filesystem
Must contain utilities and filesMust contain utilities and filessufficient to boot the operatingsufficient to boot the operatingsystemsystem
Should contain utilities needed byShould contain utilities needed bythe system administrator to repair orthe system administrator to repair orrestore a damaged systemrestore a damaged system
Should be relatively smallShould be relatively small Software should not create files orSoftware should not create files or
directories in the root filesystemdirectories in the root filesystem
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
10/305
1010
The usrFilesystemThe usrFilesystem
Contain system utilities andContain system utilities andprograms that do not appear in theprograms that do not appear in the
root partitionroot partition User programs will often appear inUser programs will often appear in
/usr/bin/usr/bin
Some system administrationSome system administrationprograms may appear in /usrprograms may appear in /usrfilesystem as wellfilesystem as well
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
11/305
1111
The arFilesystemThe arFilesystem
Contains data such as printer spoolsContains data such as printer spoolsand log files that vary over timeand log files that vary over time
Is always changing and growing andIs always changing and growing andoften has its own partitionoften has its own partition
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
12/305
1212
root Filesystem O erviewroot Filesystem Overview
File file system available upon booting isFile file system available upon booting isthe root filesystem (/)the root filesystem (/)
In some cases, the root filesystemIn some cases, the root filesystem
contains everything on the systemcontains everything on the system
Best practice is to define multipleBest practice is to define multiplepartitions containing one or more of thepartitions containing one or more of the
directories found below root (/)directories found below root (/) When Linux boots, the partitions are mountedWhen Linux boots, the partitions are mountedand together create a single filesystemand together create a single filesystem
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
13/305
1313
//
Top of the filesystem hierarchyTop of the filesystem hierarchy
Some directories must always be aSome directories must always be a
part of the root filesystem to allowpart of the root filesystem to allowLinux to bootLinux to boot
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
14/305
1414
/bin and/sbin/bin and/sbin
Contains required system binaryContains required system binaryprogramsprograms
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
15/305
1515
/dev/dev
Contains device filesContains device files
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
16/305
1616
/etc/etc
Contains boot configurationContains boot configurationinformationinformation
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
17/305
1717
/lib/lib
Contains program librariesContains program libraries
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
18/305
1818
/boot/boot
Holds static files used by the bootHolds static files used by the bootloaderloader
Can be placed on a separate partitionCan be placed on a separate partition For use with older versions of lilo,For use with older versions of lilo,
usually on a partition below theusually on a partition below the10241024thth cylinder of a hard drive.cylinder of a hard drive.
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
19/305
1919
/home/home
Holds user filesHolds user files
Often placed on a separate partitionOften placed on a separate partition
Normally becomes the largestNormally becomes the largestpartition on the system and can evenpartition on the system and can evenbe placed on a separate physical diskbe placed on a separate physical disk
Can be shared over the network toCan be shared over the network tocentralize users files.centralize users files.
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
20/305
2020
/tm/tm
Programs use this for temporary filesPrograms use this for temporary files
Best practice to place it on aBest practice to place it on a
separate partition to preventseparate partition to preventtemporary files from filling uptemporary files from filling upvaluable disk space on the rootvaluable disk space on the rootpartitionpartition
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
21/305
2121
/var/var
Log files are stored hereLog files are stored here
Email is stored hereEmail is stored here
Print queues are stored herePrint queues are stored here RedHat stores the Apache web docsRedHat stores the Apache web docs
herehere
NIS files stored hereNIS files stored here
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
22/305
2222
/usr/usr
Holds a hierarchy of directoriesHolds a hierarchy of directoriescontaining user commands, sourcecontaining user commands, sourcecode, and documentationcode, and documentation
Often quite large in sizeOften quite large in size
Should have its own partitionShould have its own partition
/usr/sbin holds sys admin/usr/sbin holds sys adminexecutablesexecutables
/usr/bin holds user executables/usr/bin holds user executables
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
23/305
2323
Binary File LocationsBinary File Locations
User Commands System AdministrationCommands
Vendor-supplied , essential /bin /sbinVendor-suppliednonessential
/usr/bin /usr/sbin
Locally supplied,nonessential
/usr/local/bin /usr/local/sbin
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
24/305
2424
File Location CommandsFile Location Commands
whichwhich
findfind
locatelocate updatedbupdatedb
whatiswhatis
aproposapropos
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
25/305
2525
which Overviewwhich Overview
Shows the location of a commandShows the location of a commandand displays the full pathname. Usesand displays the full pathname. Usesthe PATH variable to search for thethe PATH variable to search for thecommand.command.
Command Format: whichCommand Format: which commandcommand
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
26/305
2626
find Overviewfind Overview
Locates files that match anLocates files that match anexpressionexpression
Works recursivelyWorks recursively
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
27/305
2727
find Syntax and O tionsfind Syntax and O tions
Syntax:Syntax:
find paths expressionfind paths expression
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
28/305
2828
locate Overviewlocate Overview
Locates files who names match oneLocates files who names match oneor more patternsor more patterns
Searches an index of files previouslySearches an index of files previouslycreatedcreated
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
29/305
2929
locate Syntax and O tionslocate Syntax and O tions
Syntax:Syntax:
locatelocate patternspatterns
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
30/305
3030
u datedb Overviewu datedb Overview
Refreshes or creates the slocateRefreshes or creates the slocatedatabase indatabase in/var/lib/slocate/slocate.db/var/lib/slocate/slocate.db
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
31/305
3131
u datedb Syntax and O tionsu datedb Syntax and O tions
Syntax:Syntax:
updatedb [options]updatedb [options]
Options:Options: --ee directoriesdirectories (exclude a comma(exclude a comma--
separated list of directories from theseparated list of directories from thedatabase)database)
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
32/305
3232
whatis Overviewwhatis Overview
Search the whatis database for exactSearch the whatis database for exactmatches to keywords and display thematches to keywords and display theresultsresults
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
33/305
3333
whatis Syntax and O tionswhatis Syntax and O tions
Syntax:Syntax:
whatiswhatis keywordskeywords
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
34/305
3434
apropos Overviewapropos Overview
Search the whatis database forSearch the whatis database forpartial word matches to keywordspartial word matches to keywordsand display the resultsand display the results
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
35/305
-
8/7/2019 Linux Module 1
36/305
3636
Objective 1: Use andManageObjective 1: Use andManage
Local System DocumentationLocal System Documentation Text and PagingText and Paging
The man FacilityThe man Facility
Information in /usr/docInformation in /usr/doc Info PagesInfo Pages
OdditiesOddities
Using the locate CommandUsing the locate Command
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
37/305
3737
Documentation OverviewDocumentation Overview
System Administrators should beSystem Administrators should becomfortable with navigating throughcomfortable with navigating throughdocumentation in the event that hedocumentation in the event that heor she needs helpor she needs help
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
38/305
3838
Documentation ObjectivesDocumentation Objectives
Use and Manage Local SystemUse and Manage Local SystemDocumentationDocumentation
Find Linux Documentation on theFind Linux Documentation on theInternetInternet
Write System DocumentationWrite System Documentation
Provide User SupportProvide User Support
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
39/305
3939
Use andManage Local SystemUse andManage Local System
DocumentationDocumentation Text and PagingText and Paging
The man FacilityThe man Facility
Information in /usr/docInformation in /usr/doc Info pagesInfo pages
OdditiesOddities
Using the locate CommandUsing the locate Command
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
40/305
4040
Text and PagingText and Paging
Text and Paging OverviewText and Paging Overview
Paging ProgramsPaging Programs
lessless
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
41/305
4141
Text and Paging OverviewText and Paging Overview
Each Linux system is configured withEach Linux system is configured withextensive documentation from:extensive documentation from: ProgrammersProgrammers
AuthorsAuthors Other ContributorsOther Contributors
Some documentation is quite formal whileSome documentation is quite formal whileother documentation is fairly informalother documentation is fairly informal
Combined, this documentation offers aCombined, this documentation offers arobust body of information for users androbust body of information for users andsystem administratorssystem administrators
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
42/305
4242
Paging ProgramsPaging Programs
more was a popular paging program on Unixmore was a popular paging program on Unixsystemssystems
more would give users one more screen ofmore would give users one more screen ofinformationinformation
more is known to be limited in its capabilities somore is known to be limited in its capabilities sothe less command was developedthe less command was developed
less is similar to more but offers more capabilitiesless is similar to more but offers more capabilities
less does not read all of its input before starting,less does not read all of its input before starting,
which makes it faster for large inputwhich makes it faster for large input Can also use less commands to control theCan also use less commands to control the
behavior of lessbehavior of less
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
43/305
4343
less Commandsless Commands
Command DescriptionSpace Scroll forward one screenD Scroll forward one-half screen
Return Scroll forward one lineB Scroll backward one screenU Scroll backward one-half screenY Scroll backward one lineg Go tot he beginning of the text G Go to the end of the text /pattern Search forward for a pattern which can be a regular expression
?pattern Search backward for pattern which can be a regular expressionH Display a help screen:n Display next file from command line:p Display previous file from command line
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
44/305
4444
The man FacilityThe man Facility
The man Facility OverviewThe man Facility Overview
man Commandman Command
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
45/305
4545
The man Facility OverviewThe man Facility Overview
The man facility was created to putThe man facility was created to putdocumentation books on the systemdocumentation books on the system
manpages are available for mostmanpages are available for mostcommands on the systemcommands on the system
manpages are also available formanpages are also available forimportant files, shells, devices andimportant files, shells, devices andother items on your Linux systemother items on your Linux system
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
46/305
4646
The man CommandThe man Command
Formats and displays man pages onFormats and displays man pages ona topic using a pagera topic using a pager
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
47/305
4747
man Syntax and Optionsman Syntax and Options
Syntax:Syntax:
man [options] [section] commandman [options] [section] command
Options:Options: --a Instructs man to display alla Instructs man to display all
manpages that match a name in amanpages that match a name in asequential fashionsequential fashion
--d Display debugging informationd Display debugging information --w Print the locations of manpagesw Print the locations of manpages
instead of displaying theminstead of displaying them
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
48/305
4848
Man SectionsMan Sections
Sect. Description
1 Executable programs or shell commands
8 System Administration commands
2 System calls
3 Library calls
4 Special files (usually found in /dev)
5 File formats and conventions
6 Games
7 Macro packages and conventions
9 Kernel routines
N Tcl/Tk commands4/6/20114/6/2011
-
8/7/2019 Linux Module 1
49/305
4949
Information in /usr/docInformation in /usr/doc
Some Linux users contribute theirSome Linux users contribute theirknowledge in the form of HOWTOknowledge in the form of HOWTOguides, FAQs, README files and evenguides, FAQs, README files and even
exhaustive manualsexhaustive manuals Most of this documentation ends up inMost of this documentation ends up in
/usr/doc/usr/doc
Most is ASCII and can be displayedMost is ASCII and can be displayed
using a pager programusing a pager program Contents of /usr/doc can be categorizedContents of /usr/doc can be categorized
as follows:as follows: Package RelatedPackage Related
FAQFAQ
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
50/305
5050
Package elatedPackage elated
usually useful bits of informationusually useful bits of informationincludes with the program sourceincludes with the program source
Contains documentation files that areContains documentation files that areoften specific to a version of aoften specific to a version of apackagepackage
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
51/305
5151
FAQFAQ
Contains detailed information in aContains detailed information in aQ&A formatQ&A format
Man important FAQs resides inMan important FAQs resides in
usr/doc/FAQusr/doc/FAQ FAQs are often formatted in:FAQs are often formatted in:
HTML (web browser friendly)HTML (web browser friendly)
ps (printer friendly)ps (printer friendly) txt (plain text)txt (plain text)
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
52/305
5252
HOWTO documentsHOWTO documents
Details information on how toDetails information on how toperform a certain taskperform a certain task
Often serve as reference material forOften serve as reference material fornew administratorsnew administrators
Often stored in /usr/doc/HOWTOOften stored in /usr/doc/HOWTO
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
53/305
5353
InfopagesInfopages
Are part of a system called textinfoAre part of a system called textinfowhich uses a single source file towhich uses a single source file todisplay information on screen and ondisplay information on screen and onpaperpaper
Is hypertext and creates a browserIs hypertext and creates a browserlike interface on a terminal orlike interface on a terminal or
terminal windowterminal window
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
54/305
5454
info Commandsinfo Commands
Command DescriptionTab Mov among y rt xt links
Ent r ollow y rt xt linkst rn to t topof t menu? List all info commandsP andn Move toprevious andnextpages respectivelyu Moveupone level in t eTextinfo ierarc yq Terminate t e systemh Showaprimer for first timeusers
/string Enter a string/patter Search forward for pattern,which canbea regular expression
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
55/305
5555
Using the locate CommandUsing the locate Command
The locate command is handy as itThe locate command is handy as itcan return all instances of thecan return all instances of thecommand or command fragment youcommand or command fragment youenterenter
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
56/305
5656
Documentation on the netDocumentation on the net
The Linux Documentation ProjectThe Linux Documentation Project
Usenet NewsgroupsUsenet Newsgroups
Mailing ListsMailing Lists Vendor Web Sites and OtherVendor Web Sites and Other
ResourcesResources
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
57/305
5757
The Linux DocumentationThe Linux Documentation
ProjectProject Most documentation, includingMost documentation, including
HOWTOs, is part of an organizedHOWTOs, is part of an organizedapproach to system documentationapproach to system documentation
Linux Documentation Project (LDP) isLinux Documentation Project (LDP) isa group of writers, proofreaders anda group of writers, proofreaders andeditors to create systemeditors to create systemdocumentation for Linuxdocumentation for Linux
The url is http://www.linux.orgThe url is http://www.linux.org
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
58/305
5858
The Linux DocumentationThe Linux Documentation
ProjectProject Documentation handled by LDP includesDocumentation handled by LDP includes
online documents, manpages, HOWTOsonline documents, manpages, HOWTOsand a complete set of reference guidesand a complete set of reference guidesincluding:including: Installation and Getting Started GuideInstallation and Getting Started Guide
The Linux Users GuideThe Linux Users Guide
The Linux System Administrators GuideThe Linux System Administrators Guide
The Linux Programmers GuideThe Linux Programmers Guide
The Linux KernelThe Linux Kernel
The Linux Kernel Hackers GuideThe Linux Kernel Hackers Guide
The Linux Kernel Module Programming GuideThe Linux Kernel Module Programming Guide
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
59/305
5959
Usenet NewsgroupsUsenet Newsgroups
Worldwide bulletin board serviceWorldwide bulletin board service
Messages are posted to a users localMessages are posted to a users localnews server in a newsgroupnews server in a newsgroup
Can usually access Usenet contentCan usually access Usenet contentthrough your ISPthrough your ISP
Can read messages with a newsCan read messages with a newsreader applicationreader application
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
60/305
6060
Important Usenet NewsgroupsImportant Usenet Newsgroups
comp.os.linuxcomp.os.linux
comp.os.linux.advocacycomp.os.linux.advocacy
comp.os.linux.developmentcomp.os.linux.development
comp.os.linux.announcecomp.os.linux.announce
comp.os.linux.hardwarecomp.os.linux.hardware
comp.os.linux.answerscomp.os.linux.answers
comp.os.linux.networkingcomp.os.linux.networking comp.os.linux.xcomp.os.linux.x
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
61/305
6161
Mailing ListsMailing Lists
Mailing list is an email autoresponderMailing list is an email autoresponderwith a known list of mail recipientswith a known list of mail recipients
Inbound mail to the list server will beInbound mail to the list server will bemirrored to each of the othermirrored to each of the otherrecipients on the listrecipients on the list
Mailing list mail is more likely to beMailing list mail is more likely to be
read by subscribers than usenetread by subscribers than usenetinformationinformation
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
62/305
6262
CertificationCertification
http://www.brainbench.comhttp://www.brainbench.com
http://www.linuxcertification.comhttp://www.linuxcertification.com
http://www.lpi.orghttp://www.lpi.org http://www.redhat.com/rhcehttp://www.redhat.com/rhce
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
63/305
6363
CommerceCommerce
http://www.elinux.comhttp://www.elinux.com
http://www.linuxcentral.comhttp://www.linuxcentral.com
http://www.linuxmall.comhttp://www.linuxmall.com
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
64/305
6464
DistributionsDistributions
http://www.calderasystems.comhttp://www.calderasystems.com
http://www.debian.orghttp://www.debian.org
http://www.linuxhttp://www.linux--mandrake.commandrake.com http://www.redhat.comhttp://www.redhat.com
http://www.slackware.comhttp://www.slackware.com
http://www.suse.comhttp://www.suse.com http://www.turbolinux.comhttp://www.turbolinux.com
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
65/305
-
8/7/2019 Linux Module 1
66/305
6666
GeneralGeneral
http://www.linux.comhttp://www.linux.com
http://www.linux.orghttp://www.linux.org
http://www.linuxberg.comhttp://www.linuxberg.com
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
67/305
6767
GUIsGUIs
http://www.afterstep.orghttp://www.afterstep.org
http://www.eazel.comhttp://www.eazel.com
http://www.gnome.orghttp://www.gnome.org http://www.kde.orghttp://www.kde.org
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
68/305
6868
NewsNews
http://slashdot.orghttp://slashdot.org
http://www.linuxplanet.comhttp://www.linuxplanet.com
http://www.lwn.comhttp://www.lwn.com http://www.linuxjournal.comhttp://www.linuxjournal.com
http://www.linuxtoday.comhttp://www.linuxtoday.com
http://www.linuxpr.comhttp://www.linuxpr.com http://www.oreillynet.comhttp://www.oreillynet.com
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
69/305
6969
Open SourceOpen Source
http://www.fsf.orghttp://www.fsf.org
http://www.gnu.orghttp://www.gnu.org
http://www.kernelnotes.orghttp://www.kernelnotes.org http://freshmeat.orghttp://freshmeat.org
http://www.sourceforge.nethttp://www.sourceforge.net
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
70/305
7070
ProjectsProjects
http://www.apache.orghttp://www.apache.org
http://www.squidcache.orghttp://www.squidcache.org
http://www.linuxrouter.orghttp://www.linuxrouter.org http://www.linuxppc.orghttp://www.linuxppc.org
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
71/305
7171
Search EnginesSearch Engines
http://www.google.comhttp://www.google.com
http://www.altavista.comhttp://www.altavista.com
http://www.northernlight.comhttp://www.northernlight.com http://www.yahoo.comhttp://www.yahoo.com
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
72/305
7272
SupportSupport
http://www.linuxcare.orghttp://www.linuxcare.org
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
73/305
-
8/7/2019 Linux Module 1
74/305
7474
X Window SystemX Window System
http://www.x.orghttp://www.x.org
http://www.sgree86.comhttp://www.sgree86.com
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
75/305
7575
Role ofa SystemRole ofa SystemAdministratorAdministrator
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
76/305
7676
SuperuserSuperuser
Known as the root userKnown as the root user
Has a uid of 0Has a uid of 0
Most powerful account on the systemMost powerful account on the system By default cannot remotely login asBy default cannot remotely login as
rootroot
By default cannot use root as an ftpBy default cannot use root as an ftpuseruser
Home directory of /rootHome directory of /root4/6/20114/6/2011
-
8/7/2019 Linux Module 1
77/305
7777
SuperuserSuperuser
Should not use superuser forShould not use superuser foreveryday use because:everyday use because:
Normally do not need rootNormally do not need root--level accesslevel access
If a mistake is made when logged on asIf a mistake is made when logged on asroot, it can have systemroot, it can have system--widewideimplicationsimplications
Can read other users email and filesCan read other users email and fileswhich can cause ethical issueswhich can cause ethical issues
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
78/305
7878
Process UsersProcess Users
Restricted access to processRestricted access to process--requiredrequiredresourcesresources
Found on all UNIX and Linux systemsFound on all UNIX and Linux systems
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
79/305
7979
Unprivileged UsersUnprivileged Users
Regular users that have restricted toRegular users that have restricted toareas/activities for which they have beenareas/activities for which they have beengiven permissionsgiven permissions
Typically need only run programs andTypically need only run programs andsave documents and datasave documents and data
Created as necessary by a systemCreated as necessary by a systemadministrator using the useradd commandadministrator using the useradd command
or the LinuxConf graphical utilityor the LinuxConf graphical utility
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
80/305
8080
Module : UserModule : User
ManagementManagement/etc/passwd, /etc/shadow,/etc/passwd, /etc/shadow,/etc/group, /etc/gshadow/etc/group, /etc/gshadow
Useradd, usermod, userdelUseradd, usermod, userdelGroupadd, groupmod,Groupadd, groupmod,
groupdelgroupdel
Chage, passwdChage, passwd
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
81/305
8181
/etc/passwdfile/etc/passwdfile
steve:x:500:100:steve gamblin:/home/steve:/bin/bash
This is the file that contains account information ofusers in a Linux system. It can be read by everyone
who is logged into the server. Only the root account haswrite privileges.
Username:password:uid:gid:comment:home:shell
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
82/305
8282
/etc/passwd: username/etc/passwd: username
Most unixes up to 8 charactersMost unixes up to 8 characters
Has to start with a letterHas to start with a letter
May have numbersMay have numbers Should be lowercaseShould be lowercase
Must be uniqueMust be unique
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
83/305
8383
/etc/passwd: password/etc/passwd: password
If it contains an "x" then theIf it contains an "x" then thepassword is in a special file calledpassword is in a special file called/etc/shadow/etc/shadow
Most unixes min 6 charactersMost unixes min 6 characters
Most unixes up to 8 charactersMost unixes up to 8 characters
May contain spacesMay contain spaces
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
84/305
8484
/etc/passwd: uid/etc/passwd: uid
Uid is the unique numerical id number forUid is the unique numerical id number forthe user.the user.
Technically should be unique, but accountsTechnically should be unique, but accounts
can be setup to have the same uidcan be setup to have the same uid Odd things can happen with same uidsOdd things can happen with same uids
Generally uid from 0 to 99 reserved forGenerally uid from 0 to 99 reserved forsystem accountssystem accounts
100 to 60000 for normal users100 to 60000 for normal users
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
85/305
8585
/etc/passwd: gid/etc/passwd: gid
Number of the primary group thatNumber of the primary group thatthe user belongs to.the user belongs to.
The users secondary groupThe users secondary group
memberships defined in thememberships defined in the/etc/group file/etc/group file
Gids from 0 to 99 reserved forGids from 0 to 99 reserved forsystem groups.system groups.
100 to 60000 for general use.100 to 60000 for general use.
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
86/305
8686
/etc/passwd: Comment/etc/passwd: Comment
This may or may not containThis may or may not containinformation.information.
Should be kept to a minimumShould be kept to a minimum
Usually contains users real nameUsually contains users real name
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
87/305
8787
/etc/passwd: home/etc/passwd: home
Contains the location of the homeContains the location of the homedirectorydirectory
Most system accounts do not have aMost system accounts do not have ahome directoryhome directory
The root accounts home directory isThe root accounts home directory isusually /rootusually /root
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
88/305
8888
/etc/passwd: Default Shell/etc/passwd: Default Shell
This contains the default shell thatThis contains the default shell thatthe Sys Admin has assigned to thethe Sys Admin has assigned to theuser.user.
In Linux most common shell is bashIn Linux most common shell is bash
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
89/305
8989
/etc/shadow/etc/shadow
steve:$1$wW4mgdYE$yQ2eQrU:11768:0:99999:7:::
This file contains the password for the user. It is onlyreadable by the root user.
Username:password:Days since Jan 11970 that password has been changed:Days before password can be changed:
Days after which password must be changed:Days before password is to expire that user is warned:Days after password expires that account is disabled:Days since Jan 1,1970 that account is disabled:A reserved field:4/6/20114/6/2011
-
8/7/2019 Linux Module 1
90/305
9090
UserManagement: useraddUserManagement: useradd
To add user accounts by commandline you use theuseradd command.Command Format: useradd [options] username
Options-c "comment" Comment field-d /home/user home directory-u uid specify uid-g group specify primary gid-G group1, secondary groups-m create home directory-s /bin/shell specify default shell-k /etc/skel specify default profiles-n turns off group same as user creation
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
91/305
9191
Useradd ExampleUseradd Example
Example:To create a user called bob.
useradd bob
To create a user called billy, but you want to turn offthe group creation and to have billy assigned to theusers group. and you want to add in Billy's name in the
comment field
useradd n c "Billy Smith" billy
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
92/305
9292
UseradddefaultsUseradddefaults
You can define preset options, so that you don't have tospecify them when you use the useradd command.
useradd D will list all of the defaults defined.
Command Format: useradd D [options]
Options-b home dir sets default home directory-e default expiry date sets default expiry date-g group sets default group *-s shell sets default shell4/6/20114/6/2011
-
8/7/2019 Linux Module 1
93/305
9393
UseraddUseradd D ExampleD Example
Example:To set the default shell to the tcsh shell.
useradd D s /bin/tcsh
The file that contains the useradd default values is/etc/default/useradd
Remember that you need to use the n option to havethe default group option to work in Redhat.
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
94/305
9494
UserManagement: usermodUserManagement: usermod
The usermod command allows you to modify a usersaccount.
Command Format: usermod [options] usernameOptions-c "comment" Comment field-d /home/user change home directory-m create home directory-u uid specify new uid-g group chnage primary gid-l username change username-G group1, secondary groups-s /bin/shell specify new default shell4/6/20114/6/2011
-
8/7/2019 Linux Module 1
95/305
9595
UserManagement: usermodUserManagement: usermod
The usermod also allows you to lock and unlockaccounts.
Command Format: usermod [options] username
Options-L Lock the account
-U Unlock the account
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
96/305
9696
Usermod ExampleUsermod Example
Example:To change the uid of the user bob
usermod u 550 bob
This will also change all of the uids of the files of theuser bob, to the new ones, if they are in the home
directory. To change any that are out side thehomedirectory, you would use the find command (with theexec option).
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
97/305
9797
UserManagement: userdelUserManagement: userdel
Userdel will delete a user from the /etc/passwd file andthe /etc/shadow file.
Command Format: userdel [option] usernameOption-r Delete home directory.
Example:You want to delete the user named bobuserdel r bob
This will delete his home directory as well.4/6/20114/6/2011
B i UNIX C dB i UNIX C d
-
8/7/2019 Linux Module 1
98/305
9898
Basic UNIX CommandsBasic UNIX Commands
unameuname Displays the name of the current operatingDisplays the name of the current operatingsystemsystem
date Displays the date and time
cal Displays a calendar for the current month and year.
ls Displays the directory listing
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
99/305
9999
Command Line SyntaxCommand Line Syntax
command option(s) argument(s)command option(s) argument(s)
CommandCommand Executable commandExecutable command
OptionOption How the command will be ranHow the command will be ran
ArgumentArgument The file, directory or text youThe file, directory or text you
are utilizing for the commandare utilizing for the command
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
100/305
100100
Control CharactersControl Characters
Control Characters perform specific tasksControl Characters perform specific tasksat the command lineat the command line
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
101/305
101101
Viewing Online DocumentationViewing Online Documentation
The online UNIX reference manuals provide aThe online UNIX reference manuals provide adetailed description of command and examples ofdetailed description of command and examples ofhow they are usedhow they are usedCommand:
Result:
4/6/20114/6/2011
S lli h M PS lli h M P
-
8/7/2019 Linux Module 1
102/305
102102
Scrolling the Man PagesScrolling the Man Pages
Keys used to control the scrolling capabilities in theKeys used to control the scrolling capabilities in the
manualmanual..
4/6/20114/6/2011
S hi fS hi f
-
8/7/2019 Linux Module 1
103/305
103103
Searching forman pagesSearching forman pages
To list the online manuals that are availableTo list the online manuals that are availableyou can use theyou can use the kk option. This will allow youoption. This will allow youlist all of the manuals in reference to thelist all of the manuals in reference to theparameter of your command.parameter of your command.
4/6/20114/6/2011
D t i i C t UD t i i C t U
-
8/7/2019 Linux Module 1
104/305
104104
Determining Current UsersDetermining Current Users
TheThe whowhologged in users and whatlogged in users and whatsessions they are currently utilizing onsessions they are currently utilizing onthe server.the server.
4/6/20114/6/2011
Id tif i UId tif i U
-
8/7/2019 Linux Module 1
105/305
105105
Identifying a UserIdentifying a User
TheThe who am iwho am i command allows you to identifycommand allows you to identifywho you are logged in as.who you are logged in as.
4/6/20114/6/2011
Id tif i U G D t ilId tif i U G D t il
-
8/7/2019 Linux Module 1
106/305
106106
Identifying UserGroupDetailsIdentifying UserGroupDetails
Use theUse the idid command to identify the usercommand to identify the userID and group IDID and group ID
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
107/305
P d C dP d C d
-
8/7/2019 Linux Module 1
108/305
108108
Passwd CommandPasswd Command
The password command will assign a password to anaccount.
Command Format: passwd [option] username
Option-l Lock the account-u Unlock the account
4/6/20114/6/2011
P d E lP d E l
-
8/7/2019 Linux Module 1
109/305
109109
Passwd ExamplesPasswd Examples
You want to lock the bob account.passwd l bob
You want to change or set bob's passwordasswd bob
4/6/20114/6/2011
/ t // t /
-
8/7/2019 Linux Module 1
110/305
110110
/etc/group/etc/group
This is the file that contains the names of the groups,the gid associated with the group, and the groupsmembers.
bin:x:1:root,bin,daemon
Group:password:group members
/etc/gshadow holds passwords for the /etc/group file.This is not a popular function. But can be set with thegpasswd command.
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
111/305
-
8/7/2019 Linux Module 1
112/305
112112
GroupManagement: groupmodGroupManagement: groupmod
You can modify an existing group with the groupmodcommand.
Command Format: groupmod [option] group
Option-g gid change the gid-n name change the group name to name
ExampleTo change the group name from web to accountgroupmod n account web4/6/20114/6/2011
G M n gement g delG M n gement g del
-
8/7/2019 Linux Module 1
113/305
113113
GroupManagement: groupdelGroupManagement: groupdel
To delete a group from the /etc/group file and fromthe system, use the groupdel command.
Command Format: groupdel group
ExampleTo delete the account group.groupdel account
4/6/20114/6/2011
Password Aging:Password Aging: chagechage
-
8/7/2019 Linux Module 1
114/305
114114
PasswordAging:PasswordAging: chagechage
The chage command will set password aging parameters
Command Format: chage [options] user-l displays current settings.-m # minimum days between password changes-E Set expiry date mm/dd/yyyy-M # max days a password is valid
-W # number of days for warning of password change
ExampleTo set the expiry date of the user bobchage E 05/10/2002 bob4/6/20114/6/2011
Initialization FilesInitialization Files
-
8/7/2019 Linux Module 1
115/305
115115
Initialization FilesInitialization Files
Two sets of initialization files:Global Set for all usersLocal Allows for the user to customize their
environment.
Global Local/etc/profile ~/.bash_profile
/etc/bashrc ~/.bashrc
4/6/20114/6/2011
Initialization FilesInitialization Files
-
8/7/2019 Linux Module 1
116/305
116116
Initialization FilesInitialization Files
Processing order
/etc/profile
~/.bash_profile
~/.bashrc/etc/bashrc
This is fuzzy, as~.bashrc calls/etc/bashrc
If you start a sub shell~/.bashrc/etc/bashrc
Processed only once, per login
4/6/20114/6/2011
/etc/skel/etc/skel
-
8/7/2019 Linux Module 1
117/305
117117
/etc/skel/etc/skel
If you want to modify the initial .bash_profile and.bashrc files that will be copied into the users
directory, they are located in the /etc/skel directory.
You can create multiple skel directories, if you findthat you find that users need customized initializationfiles, based on group needs with the k option in the
useradd command.
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
118/305
118118
Module : SystemModule : System
SecuritySecurityReview ofPermissionsReview ofPermissions
S and t bitsS and t bits
Review of Chown, chmod,Review of Chown, chmod,umaskumask
The syslog daemonThe syslog daemon4/6/20114/6/2011
Users and GroupsUsers and Groups
-
8/7/2019 Linux Module 1
119/305
119119
Users andGroupsUsers andGroups
Talk about users and groups
4/6/20114/6/2011
Command: lsCommand: ls ll
-
8/7/2019 Linux Module 1
120/305
120120
Command: lsCommand: ls--ll
total 6drwxr-xr-x 3 steve staff ch1
drwxr-xr-x 3 steve staff ch2
drwxr-xr-x 3 steve staff ch3
-rw-r--r-- 1 steve staff fullnotes
-rw-r--r-- 1 steve staff outline
d rwx r-x r-xFile TypeD Directory- Regular File
UsersPermissions
GroupPermissions
OthersPermissions
User (owner) Group File/dir name
4/6/20114/6/2011
File Security: PermissionsFile Security: Permissions
-
8/7/2019 Linux Module 1
121/305
121121
File Security: PermissionsFile Security: Permissions
File permissions determine how users can use files andtraverse directories on the server.
Three sets of permissions:User- Owner of the file/ directoryGroup- A grouping of usersOther- (Public) Anyone expect for the owner andmembers of the group the file/dir belongs to
Three types of permissions:r- Read
w- Write
x- Execute
- Norights
4/6/20114/6/2011
File Security: PermissionsFile Security: Permissions
-
8/7/2019 Linux Module 1
122/305
122122
File Security: PermissionsFile Security: Permissions
File Rights:rFile can be read or copied
w File can be modifiedx File can be executed (run), binary or shell scripts- No rights to file
4/6/20114/6/2011
File PermissionsFile Permissions
-
8/7/2019 Linux Module 1
123/305
123123
File PermissionsFile Permissions
File Permissions:--x You can execute only *-w- You can modify only *
r-- You can read only-wx You can modify and execute *r-x You can read and executerw- You can read and modifyrwx You can read,modify and execute
If you do not have read rights to a file you cannot copy it,But you can move it!
4/6/20114/6/2011
File Security: PermissionsFile Security: Permissions
-
8/7/2019 Linux Module 1
124/305
124124
File Security: PermissionsFile Security: Permissions
Directory Rights:rDirectory contents can be listed with lsw Files can be add or deletedx Access to directory is granted- No rights to directory
4/6/20114/6/2011
Directory PermissionsDirectory Permissions
-
8/7/2019 Linux Module 1
125/305
125125
Directory PermissionsDirectory Permissions
Directory Permissions:--x You have access but can't list, delete or create *-w- Cannot do anythingr-- You can list the directory contents only *r-x You can list and travel through the directoryrw- You can list the directory contents only *-wx You can add or delete files, but can't list them,
you can travel through the directoryrwx You can list, add, delete and travel through thedirectory
4/6/20114/6/2011
PermissionsPermissions
-
8/7/2019 Linux Module 1
126/305
126126
PermissionsPermissions
Permissions are processed in the following way:
Every user has a uid numberEvery group has a gid numberTo find out your uid/gid useThe id command.
$ iduid=1001(steve) gid=10(staff)
4/6/20114/6/2011
Command: lsCommand: ls--ll
-
8/7/2019 Linux Module 1
127/305
127127
Command: lsCommand: ls--ll
total 6drwxr-xr-x 3 steve staff ch1
drwxr-xr-x 3 steve staff ch2
drwxr-xr-x 3 steve staff ch3
-rw-r--r-- 1 steve staff fullnotes
-rw-r--r-- 1 steve staff outline
d rwx r-x r-xFile TypeD Directory- Regular File
UsersPermissions
GroupPermissions
OthersPermissions
User (owner) Group File/dir name
4/6/20114/6/2011
Changing Permissions: chmodChanging Permissions: chmod
-
8/7/2019 Linux Module 1
128/305
128128
Changing Permissions: chmodChanging Permissions: chmod
Changing file and directory permissions is done throughchmod. You have to own the file or directory in order to beable to change its permissions.
Two ways to use chmod: symbolic modeCommand Format:
chmod [option] [who][op-code][permission] fileOptions-R Recursively make changes
who op-code permissionu user = set rreadggroup + add w writeo other - remove x executea
all
4/6/20114/6/2011
Chmod: Symbolic ModeChmod: Symbolic Mode
-
8/7/2019 Linux Module 1
129/305
129129
Chmod: SymbolicModeChmod: SymbolicMode
Examples:
$ cd;touch changeme
To add execute permissions to the file use the command:$ chmod u+x changeme
You can also combine options in the command$ chmod u-x,o-r changeme
In symbolic mode you can specify what permissions youwant to have changed without knowing what permissionsare already set.
4/6/20114/6/2011
Changing Permissions: chmodChanging Permissions: chmod
-
8/7/2019 Linux Module 1
130/305
130130
Changing Permissions: chmodChanging Permissions: chmod
Octal Mode:Command Format: chmod [option] [octal numbers] file
Option-R Recursively make changesOctal numbers:
User Group Otherr=4 r=4 r=4
w=2 w=2 w=2x=1 x=1 x=1
(User total x 100)+(Group total x10) +(Other total)= Octal4/6/20114/6/2011
Chmod ExamplesChmod Examples
-
8/7/2019 Linux Module 1
131/305
131131
Chmod ExamplesChmod Examples
Examples:
$ cd;touch changeme
$ chmod 744 changeme
$ chmod 640 changeme
When you change permissions in octal mode, you mustspecify all of the permissions.
4/6/20114/6/2011
New Permissions Files: s bitNew Permissions Files: s bit
-
8/7/2019 Linux Module 1
132/305
132132
New Permissions Files: s bitNew Permissions Files: s bit
The s bit can be applied to the user and the groupportions. The s bit is used when the file is executed.
When the s bit is applied to the user part of thepermissions, it means "run this program as if youare the user"Look at /usr/bin/passwd
When the s bit is applied to the group part of thepermissions, it means "run this program as if youare a member of the group"Look at /usr/bin/wall4/6/20114/6/2011
New Permissions Dir: s bitNew Permissions Dir: s bit
-
8/7/2019 Linux Module 1
133/305
133133
New Permissions Dir: s bitNew Permissions Dir: s bit
The s bit can be applied to the group portion of adirectories permissions. It has now effect if it isSet on the user or other portions.
When a file is saved in a directory with the s bit seton the group,its group ownership will be set to thedirectories group owner.
4/6/20114/6/2011
Setting the s bitSetting the s bit
-
8/7/2019 Linux Module 1
134/305
134134
Setting the s bitSetting the s bit
To set the s bit for the user, you can use either thesymbolic method or the octal method.
Symbolic method:
Setting it for the userchmod u+s runme.sh
Setting it for the groupchmod s+g runme.sh
4/6/20114/6/2011
Setting the s bitSetting the s bit
-
8/7/2019 Linux Module 1
135/305
135135
Setting the s bitSetting the s bit
To set the s bit in the octal mode, we add a new set:Special User Group Other
Special:4 = user s bit in binary: 1002 = group s bit in binary: 010
4/6/20114/6/2011
Setting the s bit: OctalSetting the s bit: Octal
-
8/7/2019 Linux Module 1
136/305
136136
Setting the s bit: OctalSetting the s bit: Octal
Octal setting user s bit on a filechmod 4755 runme.sh
Octal setting the group s bit on a filechmod 2755 runme.sh
Setting both user and group s bits on a file
chmod 6755 runme.sh
4/6/20114/6/2011
The "sticky" bitThe "sticky" bit
-
8/7/2019 Linux Module 1
137/305
137137
The sticky bitThe sticky bit
The sticky bit is applied only to a directory and hasthe effect of only allowing the owner, directory owner
or root the ability to delete or remove files in thatdirectory.Look at /tmp
4/6/20114/6/2011
Setting the t bitSetting the t bit
-
8/7/2019 Linux Module 1
138/305
138138
Setting the t bitSetting the t bit
To set the t bit for the user, you can use either thesymbolic method or the octal method.
Symbolic method:
chmod o+t /data
4/6/20114/6/2011
Setting the t bitSetting the t bit
-
8/7/2019 Linux Module 1
139/305
139139
Setting the t bitSetting the t bit
To set the t bit in the octal mode, we use it on the newset:Special User Group Other
Special:1 = t bit Binary 001
4/6/20114/6/2011
Setting the t bit: OctalSetting the t bit: Octal
-
8/7/2019 Linux Module 1
140/305
140140
Setting the t bit: OctalSetting the t bit: Octal
Octal setting user t bit on a directory
mkdir /public
chmod 1777 /public
4/6/20114/6/2011
The special setThe special set
-
8/7/2019 Linux Module 1
141/305
141141
The special setThe special set
You can combine the special bits, if you need to.
For Example:You want every file created in the /public to belong tothe group html and to have the sticky bit, so that onlythe owner, directory owner or root can delete files in
that directory.
chown steve:html /publicchmod 3777 /public
4/6/20114/6/2011
Permissions: DefaultsPermissions: Defaults
-
8/7/2019 Linux Module 1
142/305
142142
Permissions: DefaultsPermissions: Defaults
When you create a file or directory it is given defaultpermissions.Defaults:
Files rw- rw- rw- (666)Dir. rwx rwx rwx (777)
These defaults can be changed with the umask command.Command Format: umask [octal number]
User Group Otherr=4 r=4 r=4
w=2 w=2 w=2
x=1 x=1 x=1
(User total x 100)+(Group total x10) +(Other total)= Octal4/6/20114/6/2011
Permissions: umaskPermissions: umask
-
8/7/2019 Linux Module 1
143/305
143143
Permissions: umaskPermissions: umask
To view your current umask filter:$ umask022 The OS creates this for you
$ touch changeme
Default permissions: rw- rw- rw- (666)Umask filter: --- -w- -w- (022)
Result rw- r- r- (644)
If a file exists and you copy it, the umask is applied tothe file. It does not affect file/directory moves.4/6/20114/6/2011
Permissions: umaskPermissions: umask
-
8/7/2019 Linux Module 1
144/305
144144
Permissions: umaskPermissions: umask
Umask only takes away rights, does not add them. Youcan set your own umask to suit your security needs.
Example:$ umask 027 Files: Allows all default rights to the
owner/creator, gives group usersread only rights, and no rights toeveryone else to newly created files.
Dir: Allows all rights to users, givesread and execute permissions togroup users and no permissions toeveryone else to newly createddirectories.
4/6/20114/6/2011
Chown: Changing OwnershipChown: Changing Ownership
-
8/7/2019 Linux Module 1
145/305
145145
C o C a g g O e s pC o C a g g O e s p
chown changes the ownership of a file or directory.
Command Format: chown [-options] file-R recursively change files
Example:$ touch changeme$ chown root changeme
$ ls l changeme-rw-r--r-- 1 root staff 0 Jan 6 15:19 changeme
4/6/20114/6/2011
Chown AgainChown Again
-
8/7/2019 Linux Module 1
146/305
146146
gg
To change a files ownership and group assignment at thesame time use the chown command.
Command Format: chown user:group [option] file
Or chown user.group [option] fileOr chown .group [option] file
-R Recursively change assignments
Example:$ touch allchange$ chown root:web allchange$ ls l allchange-rw-r--r-- 1 root web 0 Jan 6 15:51 allchange4/6/20114/6/2011
chgrpchgrp
-
8/7/2019 Linux Module 1
147/305
147147
g pg p
To change the group assignment of a file or directory,use the chgrp command.
Command Format: chgrp [options] file-R recursively change files
Example:$ touch mygroupfile
$ chgrp web mygroupfile$ ls l mygroupfile-rw-r--r-- 1 steve web 0 Jan 6 15:46 mygroupfile
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
148/305
148148
Module 4: CommandModule 4: Command
ReviewReview
Cp, mv, touch,Cp, mv, touch,*,?,[],{},>,,
-
8/7/2019 Linux Module 1
149/305
149149
yy
Lists the files and directories in theLists the files and directories in thedirectory specifieddirectory specified
Command Format: ls [Command Format: ls [--options] [pathname]options] [pathname]
Options:Options:
--aa Display hidden filesDisplay hidden files
--FF Display with file types * / @Display with file types * / @
--ll Display long formDisplay long form
--RR List files in subdirectoriesList files in subdirectories
--bb List hidden charactersList hidden characters
--dd List directory names but not the contentsList directory names but not the contents4/6/20114/6/2011
Commands: cat ConcatenateCommands: cat Concatenate
-
8/7/2019 Linux Module 1
150/305
150150
Cat will display text files on the screen.
Command Format: cat filename
Example:
$ cat /etc/passwd
$ cat /etc/passwd /etc/groups > sysfiles.txt
4/6/20114/6/2011
Commands: touchCommands: touch
-
8/7/2019 Linux Module 1
151/305
151151
Touch allows you to create an empty file. If the filealready exists, then touch will update the last accesstime stamp.
Command Format: touch filename
Examples:$ cd$ touch test$ touch test1 test2 test3
4/6/20114/6/2011
Commands: cpCommands: cp
-
8/7/2019 Linux Module 1
152/305
152152
pp
Copy files and or directories from one location to another
Command Format: cp [option] source destination
-i Confirm overwrite-r Recursive copy used in directory coping-p Preserve all information (root)Source Can be files or directoriesDestination Can be filenames or directories
Example:# cp /home/steve/readme.txt /root/# cp p /home/steve/readme.txt /root/readme2.txt
4/6/20114/6/2011
Commands: mvCommands: mv
-
8/7/2019 Linux Module 1
153/305
153153
Move or rename files or directories.
Command Format: mv [option] source destination
-i Confirm overwrite-f Force MoveSource Can be a file or directoryDestination Can be file or directory
Examples:$ cd;touch waffle;mkdir breakfast$ mv waffle eggs$ mv eggs breakfast
$ mv breakfast lunch
4/6/20114/6/2011
Commands: rmCommands: rm
-
8/7/2019 Linux Module 1
154/305
154154
Delete files (and directories) with rm.
Command Format: rm [option] filename
-i Confirm deletion-r Remove Directory and its contents-f Force removal of files with no write permission
Examples:
$ cd;touch babar;mkdir house;touch house/chair$ rm i babar$ rm r house4/6/20114/6/2011
Commands: mkdirCommands: mkdir
-
8/7/2019 Linux Module 1
155/305
155155
Mkdir creates an empty directory.
Command Format: mkdir [option] directory_name
-p Create directories within directories-m set access permissions
Examples:$ cd
$ mkdir m 777 coffee$ mkdir beans$ ls -l
4/6/20114/6/2011
Commands: rmdirCommands: rmdir
-
8/7/2019 Linux Module 1
156/305
156156
The rmdir command only deletes empty directories.
Command Format: rmdir directory_name
Example:
$ cd;mkdir tempdir
$ rm tempdirIf the directory contained files and you still wanted todelete it, remember to use the rm rf command
4/6/20114/6/2011
MetacharactersMetacharacters
-
8/7/2019 Linux Module 1
157/305
157157
* Asterisk? Question Mark
[] Brackets; Semi-colon
4/6/20114/6/2011
Metacharacters: AsteriskMetacharacters: Asterisk
-
8/7/2019 Linux Module 1
158/305
158158
*Wildcard Character. Match zero or more characters.
Slang: Splat,Star
Example:$ cd /usr/bin$ ls b* List all the files that start with b
4/6/20114/6/2011
Metacharacters: Question MarkMetacharacters: Question Mark
-
8/7/2019 Linux Module 1
159/305
159159
?Match a single character.Slang: Query
Example
$ cd /usr/bin
$ lsp?? List all the files that start with pbut contain three characters
4/6/20114/6/2011
Metacharacters: BracketsMetacharacters: Brackets
-
8/7/2019 Linux Module 1
160/305
160160
[]Square BracketsMatch a single character with either a range [a-c] or
set [abc] ([bca] is the equivalent of [abc]) [A-z] for upperand lower case matching
Example:$ cd /usr/bin
$ ls[ab]* List all the files that start withletters a or b
$ ls[!ab]* Using the ! Says, don't match thesecharacters4/6/20114/6/2011
-
8/7/2019 Linux Module 1
161/305
Metacharacters: Semi ColonMetacharacters: Semi Colon
-
8/7/2019 Linux Module 1
162/305
162162
Allows for multiple commands on one line
Command Format:Command;Command;Command
Example:$ date;pwdSun Oct14 19:43:47 ADT 2001/usr/bin
4/6/20114/6/2011
Redirection: > < >Redirection: > < >
-
8/7/2019 Linux Module 1
163/305
163163
Input to a command can come from the keyboard or byusing a can put put into a file or with a >> can beAppended to the end of a file.
Error messages are usually displayed on the screen, butBy using a 2> can be redirected to a file.
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
164/305
-
8/7/2019 Linux Module 1
165/305
Redirection:
-
8/7/2019 Linux Module 1
166/305
166166
Take the contents of a file and uses it as if it were inputfrom the keyboard.
Command Format: command < file
Examples:
$ ls > lists
$ sort r < lists
4/6/20114/6/2011
Redirection: >Redirection: >
-
8/7/2019 Linux Module 1
167/305
167167
Direct any error messages into a file.
Command Format: command 2> file
Example:$ cd$ find /home name ls 2> err.log$ cat err.log
If err.log doesnt exist, it will be created and the outputwill be put into the file.
4/6/20114/6/2011
Redirection: >>Redirection: >>
-
8/7/2019 Linux Module 1
168/305
168168
Append any error messages into a file.
Command Format: command 2>> file
Example:
$ cd$ ls /usr/rack 2> err.log$ ls /bix 2>> err.log$ cat err.log
/usr/rack: No such file or directory/bix: No such file or directory
If err.log doesnt exist, it will be created and the outputwill be put into the file. The second error will be
appended to the err.log file
4/6/20114/6/2011
Multiple RedirectionMultiple Redirection
-
8/7/2019 Linux Module 1
169/305
169169
You can use all redirectors if you want to.
Command Format: command > file1 2> file2
Example:$ cd$ find / -name "*sh" > list.txt 2> err.log
If the command has some output, then it will be placedin the list.txt file, but if the command has an error, thenit will be placed in the err.log file.The append notation could be used as well (>>)4/6/20114/6/2011
Redirecting: MiscRedirecting: Misc
-
8/7/2019 Linux Module 1
170/305
170170
When you run a command, three files are opened and areassociated with that command.
They Are: Standard Input (STDIN)=0Standard Output (STDOUT)=1Standard Error (STDERR)=2
So when you redirect input or output, you are manipulatingthese files. When you want to redirect output you use the
form: command n> file.To redirect output coming from both STDOUT and STDERRinto the same file you would use the form:
command > file 2>&1 or
command >> file 2>&1
4/6/20114/6/2011
Redirecting: Discarding outputRedirecting: Discarding output
-
8/7/2019 Linux Module 1
171/305
171171
Sometimes you may not want output from a command tobe displayed on the screen and we may not want itsaved to a file. You can send output to a special file
called /dev/null which discards any output it receives.It takes the form of:command > /dev/null orcommand > /dev/null 2>&1 orcommand 2> /dev/null
Example:$ $ find / -name "*sh" > list.txt 2> /dev/null
This completes the command but all output is sent to the
bit bucket
4/6/20114/6/2011
Piping: |Piping: |
-
8/7/2019 Linux Module 1
172/305
172172
Piping takes the output of one command and uses it asinput for another command.
Command Format: command | command
Example:
$ ls /usr/bin | more
$ ls /usr/bin | sort r | more
You can have more than one pipe within a set of commands4/6/20114/6/2011
Splitting Direction with :teeSplitting Direction with :tee
-
8/7/2019 Linux Module 1
173/305
173173
Send the output of a command to the screen and to a file.Commonly used with the pipe command
Command Format: tee [option] filename-a Append to a file
Examples:
$ ls /sbin | tee sbin.list$ date | tee a sbin.list$ date | tee date.txt
4/6/20114/6/2011
BashAliasesBashAliases
-
8/7/2019 Linux Module 1
174/305
1741744/6/20114/6/2011
bash: Aliasesbash: Aliases
-
8/7/2019 Linux Module 1
175/305
175175
Aliases allow for:Creation of CommandsCreation of alternate forms of a command
Multiple commands rolled into oneCan be added to the .bashrc, so they can be availiable atlogin. They dont transfer to sub shells.
Command Format: alias command=new_command
Examples:$ alias ls='ls F'$ alias c=clear$ alias copy='cp i'$ alias home='cd;ls'
4/6/20114/6/2011
bash: Aliasesbash: Aliases
-
8/7/2019 Linux Module 1
176/305
176176
To view the current aliases in use the alias command.
Command Format: alias
To delete an alias use the unalias command.Command Format: unalias alias
Example:$ unalias ls
To temporarily bypass an alias use the back slash \
Example:$ \ls4/6/20114/6/2011
Bash Command SubstitutionBash Command Substitution
-
8/7/2019 Linux Module 1
177/305
177177
Bash offers two types of command substitution
Using the back quotes ``
Using the brackets ()
4/6/20114/6/2011
BackQuotesBackQuotes
-
8/7/2019 Linux Module 1
178/305
178178
There are some special characters to help puttinginformation into variables.Single back quotes ` ` When a command is put
between back quotes, its output is used as thevariables informationExample:$ DT=`date`$ echo $DT
Tue Oct 23 19:38:38 ADT 2001
4/6/20114/6/2011
BracketsBrackets
-
8/7/2019 Linux Module 1
179/305
179179
There are some special characters to help puttinginformation into variables.Single back quotes ` ` When a command is put
between back quotes, its output is used as thevariables informationExample:$ DT2=$(date)$ echo $DT2
Tue Oct 23 19:38:38 ADT 2001
4/6/20114/6/2011
Single QuotesSingle Quotes
-
8/7/2019 Linux Module 1
180/305
180180
Single quotes ' ' dont allow for any command or variablesubstitution.
$WO='uname n'$ echo $WO
$ WO=`uname n`$ echo ' this computer is named $WO and thetime is `date` 'this computer is named $WO and the time is Tue Oct 2319:48:51 ADT 2001
4/6/20114/6/2011
Double QuotesDouble Quotes
-
8/7/2019 Linux Module 1
181/305
181181
Double quotes allow for commands and variables to beused within the text
$ echo " this computer is named $WO and the
time is `date` "
this computer is named bob and the time is Tue Oct 2319:48:51 ADT 2001
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
182/305
182182
Module 5Module 5
Grep, cut, expand, fmt, join,Grep, cut, expand, fmt, join,nl, od,paste, pr, split, tac, tr,nl, od,paste, pr, split, tac, tr,
xargs, sedxargs, sed
4/6/20114/6/2011
grepgrep
-
8/7/2019 Linux Module 1
183/305
1831834/6/20114/6/2011
Searching in files: GrepSearching in files: Grep
-
8/7/2019 Linux Module 1
184/305
184184
Grep allows you to search files for text. Grep can alsoworks with other commands as a filter.
Command Format: grep [options] pattern filename
-i ignore case-v Search for all patterns that do not match-w Use pattern as a word-n print line number
Examples:$ grep root /etc/passwdroot:x:0:1:Super-User:/:/sbin/sh
4/6/20114/6/2011
Grep WildcardsGrep Wildcards
-
8/7/2019 Linux Module 1
185/305
185185
Wildcards^pattern Match only if pattern is at the start of a linePattern$ Match only if pattern is at the end of a line
. Match exactly one character[list] match exactly one character in list[^list] Don't match any character in list.* Match 1 or more characters* Repeat previous character
4/6/20114/6/2011
Grep ExamplesGrep Examples
-
8/7/2019 Linux Module 1
186/305
186186
cat test.txtabcabbc
acabghgtcbilabagkcxbcdvbc
$ grep ab*c test.txt
$ grep ab.*c test.txt
$ grep .*g test.txt
$ grep ^c test.txt
$ grep k$ test.txt
$ grep [^ad] test.txt4/6/20114/6/2011
cutcut
-
8/7/2019 Linux Module 1
187/305
187187
The cut command allows you to print a selected columnof a text file.
Command Format: cut [option] fileOption-c print the character in column #-d set field delimiter (default-f# print field number
Example:To list the second field in the /etc/passwd filecut d : -f 5 /etc/passwd4/6/20114/6/2011
expandexpand
-
8/7/2019 Linux Module 1
188/305
188188
Expand replaces tabs with spaces. The default is8 spaces to a tab. This does not affect the originalfile.
Command Format: expand [options] file-t # replace the tab with # of spaces.
Example:
expand t 2 list.txt
Expand t 2 list.txt > newlist.txt4/6/20114/6/2011
fmtfmt
-
8/7/2019 Linux Module 1
189/305
189189
The fmt command formats paragraphs to a uniformlength. By default, fmt will reformat each line of aparagraph to a length of 75 lines
Command Format: fmt [option] fileOption-u Set one space between words, two spaces
between sentences.-w set line length default is 75 characters.Example
4/6/20114/6/2011
tactac
-
8/7/2019 Linux Module 1
190/305
190190
Tac is the cat command in reverse.
Command Format: tac file
Example: tac grinch.txt
4/6/20114/6/2011
joinjoin
-
8/7/2019 Linux Module 1
191/305
191191
The join command allows you to two files that share acommon field.
Command Format: join [option] file1 file2Option-j1 field Use field #(column) in file one-j2 field Use field #(column) in file two-j field Use this field for both files
Example:join j11 j2 2 joiner1.txt joiner2.txt
4/6/20114/6/2011
nlnl
-
8/7/2019 Linux Module 1
192/305
192192
The nl command counts the number of lines in afile, but will adhere to certain formatting rules.The \:\:\: characters signify that the next text willbe a header.The \:\: characters signify the the following will bethe body.The \: characters signify that the next set will the
footer.
4/6/20114/6/2011
nlnl
-
8/7/2019 Linux Module 1
193/305
193193
Command Format: nl [option] fileOption-b type Body numbering options
-h type Header number options-f type Footer numbering optionsType:a Number all linesn Do not number linest Number only non empty linespPATTERN Number only lines that contain PATTERN
4/6/20114/6/2011
nl examplenl example
-
8/7/2019 Linux Module 1
194/305
194194
This counts only the lines in the body section that containthe pattern line2
nl b pline2 nltest.txt
4/6/20114/6/2011
odod
-
8/7/2019 Linux Module 1
195/305
195195
The od command allows you to view files in variousformats. This is useful for viewing binary files.
Command Format: od [option] fileOption-t type Type of output to be displayed
Type: a Named Characterc backslashx Hexidecimalo Octal
4/6/20114/6/2011
odod
-
8/7/2019 Linux Module 1
196/305
196196
Examples:
od t c od.txt
0000000 a h \n b l a h \n \n0000011
od t x od.txt0000000 620a6861 0a68616c 0000000a0000011
4/6/20114/6/2011
pastepaste
-
8/7/2019 Linux Module 1
197/305
197197
The paste command connects two or more files vertically.
Command Format: paste [option] file1 file2
-d'char' Separate columns by 'char'-s Merge, moving all of the lines of the file into
one line, and in the next file move all of the
lines into one line and place it below thefirst line.
4/6/20114/6/2011
prpr
-
8/7/2019 Linux Module 1
198/305
198198
Print a file with headers and page fills. The headerconsists of the date, time, filename and page number.
Command Format: pr [option] file
Option-d Double space-h 'header' Use 'header' instead of the filename in the
header section
-l # Set the number of lines per page-o # Set the left margin
Example:pr grinch.txt
4/6/20114/6/2011
splitsplit
-
8/7/2019 Linux Module 1
199/305
199199
Chunk up a file into separate files. The extensions of the newfiles will be in the form of aa, ab, ac
Command Format: split [option] file splitfilename-n # Split the file into # lines per segment-b # Size in bytes,
if you use #k it will be in kilobytesif you use #m it will be in megabytes
Example: split n 50 grinch.txt grinsplit_
4/6/20114/6/2011
trtr
-
8/7/2019 Linux Module 1
200/305
200200
Translate (or replace) characters from one string to thesecond string specified.
Command format: tr [option] string1 string2Option-d Delete characters from string1 from the output-s Delet repeated characters from string1
Example:tr Gg VQ < grinch.txt
4/6/20114/6/2011
xargsxargs
-
8/7/2019 Linux Module 1
201/305
201201
Xargs takes the ouput from a command and treats it as alist for another command to process.
Command Format: xargs [option] commandOption-p Prompt before executing the command
Example:
find . type f | xargs grep Grinch
4/6/20114/6/2011
sedsed
-
8/7/2019 Linux Module 1
202/305
202202
Sed is a non interactive text editor. You can edit filesthrough a sed command or through a sed script.
Command Format: sed [option] 'command' file
Option-f file Take commands from file-e cmd Next argument is a command (for
multiple commands in one sedcommand)
-g All substitutions are global-n Print only what the print cmd tells you to4/6/20114/6/2011
sedsed
-
8/7/2019 Linux Module 1
203/305
203203
Editing Commands:
'Address'd Delete a line or lines
'Address'p print a line or lines'/string/r file' Read a files/string1/string2/ Substitute one string for another
Where 'Address' can be a line number or a range of linesto be edited.
4/6/20114/6/2011
Sed: Examples: PrintingSed: Examples: Printing
-
8/7/2019 Linux Module 1
204/305
204204
To print a range of text.
sed n '5,15p' grinch.txt
Print the lines that contain the pattern Christmas
sed n '/Christmas/p' grinch.txt
4/6/20114/6/2011
Sed: Examples: SubstitutingSed: Examples: Substituting
-
8/7/2019 Linux Module 1
205/305
205205
To substitute a pattern, use the 's/string1/string2/' cmd
sed 's/Grinch/Jimmy/' grinch.txt
To add the new string to the old string
sed 's/Grinch/Jimmy&/' grinch.txt
To make changes globally. If there are paragraphs
sed 's/Grinch/Jimmy/s' grinch.txt4/6/20114/6/2011
Sed: Examples: DeletingSed: Examples: Deleting
-
8/7/2019 Linux Module 1
206/305
206206
To delete a range of text.
sed '5,15d' grinch.txt
Delete the lines that contain the pattern Christmas
sed '/Christmas/d' grinch.txt
Don't delete lines 10,20
sed '10,20!d' grinch.txt4/6/20114/6/2011
Sed: Examples: Insert FileSed: Examples: Insert File
-
8/7/2019 Linux Module 1
207/305
207207
To insert file aftermatch is found.
sed '/Grinch/r insert.txt' grinch.txt
Print the lines that contain the pattern Christmas
sed n '/Christmas/p' grinch.txt
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
208/305
-
8/7/2019 Linux Module 1
209/305
209209
Module 6Module 6
Linux File SystemLinux File System
fdisk, mkfs, mkswap, df, du,fdisk, mkfs, mkswap, df, du,
fsck, mount, umount, fuser,fsck, mount, umount, fuser,fstab, mtabfstab, mtab
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
210/305
210210
Module 7Module 7
Disk QuotasDisk Quotas
Quota, quotaon, quotaoff,Quota, quotaon, quotaoff,
quotacheck, edquota,quotacheck, edquota,repquotarepquota
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
211/305
211211
Module 8Module 8
Process ControlProcess Control
Ps, top, pstree, kill, &, fg, bg,Ps, top, pstree, kill, &, fg, bg,
jobs, nice, renicejobs, nice, renice
4/6/20114/6/2011
ProcessesProcesses
-
8/7/2019 Linux Module 1
212/305
212212
Every programme/ action/ task creates a process.Each process gets a unique number called a PID.Five types of processes:
Daemon: Started by the kernel and wait for actionParent: First process to be run, if it spawns any
processes then they are its children. I.e. Terminal sessionChild: A process run from another processOrphan: A process that doesnt end before its
parent. Sent to the init process to be shutdownZombie: A lost process. Loses its parent and canonly be removed by a reboot.
4/6/20114/6/2011
pstreepstree
-
8/7/2019 Linux Module 1
213/305
213213
Pstree allows you to see how processes are related ordependent on each other. It is presented in a humanreadable form.
Command Format: pstree [option] [pid|user]Optionsa Show cmd line args used to execute the processG View the tree using vt100 charactersn Sort by pid number instead of alphap Include PIDs in output
4/6/20114/6/2011
Processes: pstreeProcesses: pstree
-
8/7/2019 Linux Module 1
214/305
214214
[steve@bob recipes]$ pstreeinit-+-apmd
|-atd|-crond
|-deskguide_apple|-gconfd-1|-gdm---gdm-+-X| `-gnome-session|-gnome-name-serv
|-gnome-smproxy|-gpm|-httpd---8*[httpd]|-identd---identd---3*[identd]4/6/20114/6/2011
Viewing process IDs: PSViewing process IDs: PS
-
8/7/2019 Linux Module 1
215/305
215215
The ps command allows you to view the current processesrunning on the system.
Command Format: ps [options]
-a View all processes-u User format , and start time of process-f Display full listing-x Include processes without controlling
terminals-U user Display users processes-G group Display groups processes
4/6/20114/6/2011
PSPS
-
8/7/2019 Linux Module 1
216/305
216216
Since ps screens can be long its useful to combine it withsome other commands, like more and grep.
Example:
$ ps aux | moreUSER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 1 0.0 0.2 1412 520 ? S Mar28 0:04 init [5]
root 2 0.0 0.0 0 0 ? SW Mar28 0:00 [keventd]
root 3 0.0 0.0 0 0 ? SW Mar28 0:00 [kapm-idled]
Or if you want to search for a certain process$ ps aux | grep initroot 1 0.0 0.2 1412 520 ? S Mar28 0:04 init [5]
4/6/20114/6/2011
toptop
-
8/7/2019 Linux Module 1
217/305
217217
Top is like ps, but it will refesh its listing to keep thedisplay current. Top laso displays, memory and swapusage. Uptime, load and cpu status are also displayed.
Command Format: top [option]Optionsb Run in batch mode. Creates a snap shot.d Set the refresh rate in seconds.
n # refresh # of times then exitq Run with no delay, should not run as roots Disable interactive commands
4/6/20114/6/2011
Top: Interactive commandsTop: Interactive commands
-
8/7/2019 Linux Module 1
218/305
218218
When top is running, you can use it to modify processes.
Commands:
h or ? Display the help screenk Kill a processn Change the number of processes to showr Renice a process (change it's priority)u Show a specific userSpace Update Displayq quit top
4/6/20114/6/2011
pgreppgrep
-
8/7/2019 Linux Module 1
219/305
219219
Pgrep combines ps and grep into one command. This isnew to Solaris 7 & 8.
Command Format: pgrep [options] string-l Long listing-U Users process-G Groups process
Example:$ pgrep l init1 init
4/6/20114/6/2011
Job ControlJob Control
-
8/7/2019 Linux Module 1
220/305
220220
Unix allows you to be able to run multiple programsat the same time on the same terminal. This isespecially useful if you are working from a command
line interface. If you are using a window manager likeKDE/CDE or Gnome then jobs can only be controllingfrom the terminal window that they were startedfrom.
4/6/20114/6/2011
Job ControlJob Control
-
8/7/2019 Linux Module 1
221/305
221221
Commands:jobs Displays what jobs are running and itsID
bg %n Puts a job into the background (n= jobid)fg %n Brings a job back to the foregroundkill %n Ends the jobControl C Aborts the foreground job
Control Z Suspends the foreground job& Used at the end of a command to put it
in the background4/6/20114/6/2011
Job ControlJob Control
-
8/7/2019 Linux Module 1
222/305
222222
Examples:$ find / -name core > /tmp/clist 2> /tmp/c.err &Look for all files named core, put the result in the file/tmp/clist, if there are any errors list them in /tmp/c.errand with the & run it in the background.[1] 2372$ jobs[1] + Running find / -name core > /tmp/clist
Job ID Status Command
4/6/20114/6/2011
Job ControlJob Control
-
8/7/2019 Linux Module 1
223/305
223223
$ ls R / > /dev/null 2> /dev/null &[2] 2385$ jobs[2] + Running ls -R / > /dev/null 2> /dev/null &
[1] - Running find / -name core > /tmp/clist 2>
$ fg %1Brings the find job to the foreground$ ^Z(Control Z) suspends the job
$ bg %1Puts the job back to the background$ kill %2Terminates the first job
4/6/20114/6/2011
Terminating ProcessesTerminating Processes
-
8/7/2019 Linux Module 1
224/305
224224
When a process stops responding or is out of control, ithas to be terminated.Sending an interupt ( control c) will sometimes terminate
a process.The kill command is another way to end a process,epically if your terminal is locked up and you have to useanother terminal window.
4/6/20114/6/2011
-
8/7/2019 Linux Module 1
225/305
PkillPkill
-
8/7/2019 Linux Module 1
226/305
226226
Pkill combines ps and grep with kill to make search forthe process id easier.
Command Format: pkill string
Example:$ pkill find
4/6/20114/6/2011
nicenice
-
8/7/2019 Linux Module 1
227/305
227227
The nice command will let you run a command witha lower priority. A processes' priority can range from20 to +19. By default it runs at 0.
The higher the number,the lower the priority.Normal users can adjust a program from 1 to 19
Root can adjust a program from 20 to 19Default adjustment is 10
Command Format: nice [option] commandOptionn -# Adjust the priority to #--4/6/20114/6/2011
nicenice
-
8/7/2019 Linux Module 1
228/305
228228
The nice co