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entzenwerke Whitepaper Series

The Top Ten

Command Window TipsBy Whil Hentzen

Power users can go a long way just using the graphical user interface (GUI)

running on top of inu!" #ou can use the GUI for just a$out e%erything&

fro' 'aking changes to the syste' configuration to launching progra's"

Howe%er& the GUI is a fairly recent aition to the inu! worl" any har*

core an e!perience users ne%er use the GUI& an there are uses for inu!

for which a GUI woul $e out of place" +his GUI*less worl sports an

interface that can $e entere $y using a tool si'ilar to the Winows

co''an winow or ,-S pro'pt" In this whitepaper& I.ll iscuss how to get

uner the hoo $y using the inu! co''an winow"

Hentzenwerke Publishing, Inc. • [email protected] • www.hentzenwerke.com



The Top Ten Command Window Tips

/" Preface

/"/ 0opyrightCopyright 2004 Whil Hentzen. Some rights reserved. This work is licensed under the Creative Commons ttri!ution" #onCommercial"#o$erivs %icense& which !asically means that you can copy& distri!ute& and display only unaltered copies o'

this work& !ut in return& you must give the original author credit& you may not distri!ute the work 'or commercial gain& nor create derivative works !ased on it without 'irst licensing those rights 'rom the author. To view a copy o' this license& visithttp())creativecommons.org)licenses)!y"nc"nd)2.0).

/"1 2e%isions

/"1"/ History

3ersion ,ate Synopsis 4uthor

1.0.0 2004//10 !riginal "H

/"1"1 5ew %ersionThe newest version o' this document will !e 'ound at www.hentzenwerke.com.

/"1"6 7ee$ack an corrections*' you have +uestions& comments& or corrections a!out this document& please 'eel 'ree to email me at,!ooks-hentzenwerke.com,. * also welcome suggestions 'or passages you 'ind unclear.

/"6 2eferences an acknowleg'entsThanks to %/ mem!ers aron Schra! and lenn Holmer& among many others.

/"8 ,isclai'er #o warranty1 This material is provided as is& with no warranty o' 'itness 'or any particular purpose. /se the concepts& eamplesand other content at your own risk. There may !e errors and inaccuracies that in some con'igurations may !e damaging to your system. The author3s disavows all lia!ili ty 'or the contents o' this document.

5e'ore making any changes to your system& ensure that you have !ackups and other resources to restore the system to itsstate !e'ore making those changes.

ll copyrights are held !y their respective owners& unless speci'ically noted otherwise. /se o' a term in this documentshould not !e regarded as a''ecting the validity o' any trademark or service mark. #aming o' particular products or !randsshould not !e seen as endorsements.

/"9 Prere:uisitesThis document was written using 6edora Core 7.0 and assumes a !eginner,s 'amiliarity with use o' %inu via the /* and theCommand Window.

1" +he -ne Billion 5a'es for the 0o''an WinowThe %inu command window is known !y a variety o' names8 go to a %inu user"group meeting and you9ll hear terms such as:command line&; :command prompt&; :shell; or :shell prompt&; :terminal window&; :command line&; and :console&; and

perhaps even a misplaced :$<S prompt; or two.Strictly speaking& :Command %ine *nter'ace; 3C%* is the generic term 'or the so'tware device used to issue commands tothe system. C%*s are called !y di''erent names depending on what operating system you9re using& and how you9re accessing thesystem. 6or eample& /ni systems re'er to them as :shells.; *' you have direct physical access to the machine& :console; is proper usage. The application on 6edora Core and on the acintosh <S = operating system is called :Terminal&; so commonterminology re'ers to :opening another termiCron de'inition " what is it and what does it do>nal; or :opening another terminalwindow.;




The Top Ten Command Window Tips Page #

1"/" +he 'any shells of inu!5ecause we9re using %inu& you9ll run into the term :shell; rather o'ten. :Shell; is a generic term that re'ers to a class o' programs that provide C%* 'unctionality. ost %inu distri!utions come with a num!er o' shell programs& including the ?ornShell 3ksh& the C Shell 3csd and the 5ourne gain Shell 3!ash. *n 6edora Core& the de'ault shell program is !ash8 to get to it&select ain enu @ System Tools @ Terminal.

To 'ind all availa!le shells on your system& type(

cat /etc/shells

Aach o' these shells per'orms the same 'unctions& !ut they understand di''erent commands and provide di''erent !uilt"in'unctionsBconsider <pen<''ice.org Calc& icroso't Acel and %otus 7"2"& which are all spreadsheets& !ut all o' which havedi''erent menu structures and !uilt"in spreadsheet 'unctions.

5y contrast& Windows has only one shell& called :command.com&; and accessed through Drogram 6iles @ ccessories @Command Drompt. Eou can 'ind oodles o' additional in'ormation on shells here(http://www.faqs.org/faqs/unix-

faq/shell/shell-differences/etting !ack to the de'inition discussion " common terminology& then& o'ten re'ers to :opening a shell.;When you open a C%* such as !ash in %inu& you9re greeted with a window that contains an operating system prompt& like

so(

[whil@freedom whil]$

Eou type a command& press Anter& and the system 3hope'ully responds to the command with some sort o' output& or perhaps another shell prompt. 6or eample& i' * entered the command :ls "al; to list the 'iles in the current directory& * might seesomething like(

[whil@freedom whil]$ ls -aldrwx------ 58 whil whil 8192 Apr 1 18:19 .drwxr-xr-x 8 root root !9" #ar 1 1:8 ..drwxr-xr-x whil whil !9" #ar 2 1:1" %es&topdrwx------ 8 whil whil !9" #ar 2 2!:" e'ol(tio)-rwxr-xr-x 1 whil whil 1282! #ar * 18:2* i)stallatio).pdfdrwx------ 2 whil whil !9" +e, 25 18:!1 maildrwxr-xr-x 1 whil root !9" #ar 19 12:!8 m(sicdrwxrwxr-x 2 whil whil !9" #ar 22 1": ollert(ffdrwxr-xr-x whil whil !9" #ar ! 1":2 ips[whil@freedom whil]$

#ot all commands return a response8 a lot o' %inu commands produce no output i' they succeed& so all you,ll see isanother prompt.

The operating system prompt is o'ten re'erred to as a :command line; or a :command prompt.; Drograms that are designedto run !y typing a command at the operating system prompt are o'ten called :command line utilit ies.;

The command window is a rich& power'ul& programma!le tool& and many !ooks have !een written that cover it alone. Hereare the top 70 things a!out the command window *9ve 'ound to !e use'ul. The 'ollowing discussion assumes that you,re running !ash as your shell program.

6" +he 0o''an Winow title $ar The string in the tit le !ar de'aults to the name o' the current user concatenated with the host name 3machine name and thecurrent directory. *' you open a command window and change to a di''erent directory& like so(

cd /home

The string in the title !ar will change.

8" +he 0o''an pro'ptThe string in 'ront is the prompt. The de'ault !ash prompt includes the user& the host name& and the current directory. Typically&your command window will start in your home directory& so

[whil@freedom whil]$

means




The Top Ten Command Window Tips

[whil@freedom /home/whil]$

*' you,re in the :zips; su!directory o' your home directory 3i.e. )home)whil)zips& you,d see

[whil@freedom ips]$

9" 0o''an pro'pts for root %s" regular user The prompt ends in either a dollar sign 3F or a pound sign 3G. The F means that you are logged on as a regular user. The Gmeans you9re logged on as root. Eou,ll hear this again& !ut note that i' you,re root in a command window& you can easily mangleor destroy your system 3and possi!ly !low up the world with one typographic error.

;" 0usto'ize your pro'ptEou can customize the prompt !y making changes to certain con'iguration 'iles.

;"/" Shell configuration filesThe !ehavior o' the command window 3more speci'ically& the !ehavior o' the shell depends on values in several con'iguration'iles. %inu looks at the )etc)pro'ile 'ile 'irst& then the ).!ashIpro'ile 'ile& and then the ).!ashrc 'ile. 3*' you,re using a di''erentshell& these 'iles are di''erent.

The 'irst 'ile is a generic& system"wide 'ile that runs regardless o' which user is logging on& and only the systemadministrator can modi'y this 'ile. s you can see& there is a copy o' the second 'ile in every user9s home directory& and it runsevery time that user logs in. 5ecause each user has her own ).!ashIpro'ile 'ile& the command window can !e customized on a per"user !asis.

The third 'ile& which also eists in every user9s home directory& also runs on a user"!y"user !asis whenever a newcommand window is opened& ecept during initial login. s a result o' having separate .!ashIpro'ile and .!ashrc 'iles& each user can run speci'ic customizations Just during initial login or 'or all command windows ecept during initial login.

Eou might !e thinking that while this comple mechanism makes 'or wonder'ul 'lei!ility& it9s also awkward i' you wantto run some customizations 'or a speci'ic user& !ut also 'or every command window& !ecause you9d have to add the samecustomizations to !oth 'iles. Ha1 otcha covered here too. 6edora Core9s de'ault .!ashIpro'ile 'ile comes with a short script thatlooks like this(

0 et the aliases a)d f()ctio)sif [ -f /.,ashrc ]3 the)

. /.,ashrcfi

$on9t worry a!out how it works8 the important thing is that this script makes !ash run the .!ashrc 'ile in the user9s homedirectory whenever the .!ashIpro'ile script runs. s a result& i' you put all o' your customizations in .!ashrc& they9ll run 'or every shell. *' you still need customizations that run only during login& put them !e'ore this line in .!ashIpro'ile.

*t,s a good idea to put anything that takes a noticea!le amount o' time in .!ashIpro'ile so that su!"shells start up really 'ast !y doing only the minimum in .!ashrc.

nd& o' course& this all applies to the root user as well as every other user. The root user9s .!ashIpro'ile and .!ashrc 'iles arein )root& o' course.

;"1" 0usto'ize your pro'pt string #ow on to the !usiness o' customizing the prompt& since that9s what we started talking a!out. The commands *9ll !e discussingall go into the ).!ashrc 'ile& right> The !asic structure o' the command to change the prompt looks like this 3note that there

can9t !e spaces on either side o' the A+uals sign(

4167ello world6

Anter this string into your .!ashrc 'ile& save the 'ile& and then open a command window. The command prompt will simplysay(

7ello orld

That9s pro!a!ly not going to !e very help'ul& although *9ve seen a num!er o' whimsical variations& the !est !eing(




The Top Ten Command Window Tips Page

es; #aster<

Eou9ll notice that you have to enclose a string that has a space in it with +uotation marks& which is pro!a!ly no !igsurprise. *' you9ve got a string that already has a +uotation mark in it& you9ll need to use a di''erent delimiter& like so(

41=hil6s comp(ter awaits directio):=

There are a num!er o' special characters that will display certain types o' in'ormation& such as the name o' the user currently logged in& the name o' the computer& the current directory& the date& the time& and so on.Table 1 lists some commonones.

Table 1. Special characters you can use to customize your prompt.

Special

0haracter

+e!t -utput

$a %n %&'II bell character (0)*

$+ he +ate in -"eek+a onth ate- ormat (or eam3le, -ue a 2-*

$e %n %&'II esca3e character (0##*

$h he host name u3 to the irst 5.5

$H he host name

$n 6ewline

$r 'arriage return

$s he name o the shell

$t he current time in 247hour HH88&& ormat

$ he current time in 127hour HH88&& ormat

$@ he current time in 127hour am/3m ormat

$u he user name o the current user

$9 he 9ersion o bash (or eam3le, 2.00*

$w he ull name o the current working +irector (ece3t or our own home +irector, which will be +is3lae+ as5:5*

$" he basename o the current working +irector (or eam3le, 5cu3s5 instea+ o5/etc/cu3s5 an+ 5whil5 instea+ o 5:5*

$; he histor number o this comman+

$< he comman+ number o this comman+ $= I the eecti9e >I is 0, a <, otherwise a =

$$ % backslash

$? egin a seAuence o non3rinting characters, which coul+ be use+ to embe+ a terminal control seAuence into the3rom3t

$B Cn+ a seAuence o non3rinting characters

Typing :man !ash; at the command prompt 3 will give you a 'ull list o' special characters.Ta!le 2 contains a couple o' eamples to get you started. #ote that you can Just type the command in a command prompt8

you don9t have to modi'y your .!ashrc 'ile and save it each time.

Table 2 . Some sample prompt changing commands and their results.

+his co''an Prouces these results41[>w] []

(when ouDre in our home +irector*

[/etc/c(ps/i)terfaces](when ouDre in the /etc/cu3s/interaces +irector*

416[>w] %(de< 6 [] %(de<(when ouDre in our home +irector*

416[>(@>h >] %(de< 6 [whil@freedom c(ps] %(de<(when ouDre in the /etc/cu3s +irector*

416[>t] [>(@>h:>w]>$ 6 [21:52:!1] [whil@freedom:]$




The Top Ten Command Window Tips Page

;"6" 0usto'ize your pro'pt colors #ow that you,ve had 'un customizing the tet o' the prompt& let,s go another step and customize the color o' the prompt. Whywould you want to> any eperienced %inu users change the color o' the prompt 'or their root account so that it,s very& veryclear when they,re logged in as or have Ksu,dK to root.

*n order to change your prompt,s colors& you may have to speci'y !oth the 'oreground 3the characters themselves and the !ackground 3the color o' the screen !ehind the characters colors. *' you,re not care'ul& you may end up with an unreada!le

com!ination& like yellow on white or magenta on !lack.Eou may want to issue these commands in a command window while eperimenting L i' you end up with an unreada!le prompt& all you need to do is close the window and open it up again. What,s really handy is that not only are you !ack with your original prompt& !ut your command history is saved& so you,ll !e a!le to recall old eperimental commands instead o' retypingall o' those arcane characters.

*n order to change the color o' the 'oreground or !ackground& you include in your prompt string a series o' characters likeso(

41=>[>e[m?=

What do all these characters mean> The ,MNMeN, string is an escape se+uence that 'or our purposes here we won,t worry a!out3one thing it does is tell the computer not to print certain characters. The 4 changes the 'oreground color to !lue 3a ta!lelisting num!ers that map to colors 'ollows shortly& and the ,m, terminates the escape se+uence. nd the ,=, is our temporary prompt& which we,ll change !ack to our original customized prompt once we,re done eperimenting with colors.

#ow& a!out that num!ers and color ta!le. See Ta!le .

Table 3. Prompt string color values.

3alue <ffect

#0 ake oregroun+ (the characters* black

#1 ake oregroun+ re+

#2 ake oregroun+ green

## ake oregroun+ ellow

#4 ake oregroun+ blue

# ake oregroun+ magenta

# ake oregroun+ can

#) ake oregroun+ white

40 ake backgroun+ (aroun+ the characters* black

41 ake backgroun+ re+

42 ake backgroun+ green

4# ake backgroun+ ellow

44 ake backgroun+ blue

4 ake backgroun+ magenta

4 ake backgroun+ can

4) ake backgroun+ white (ou ma nee+ 0 instea+, or in a++ition*

#ote that there is no space !etween the = and the characters you type& and that the characters you type will !e the samecolor as the prompt string.

*n order to provide room !etween the prompt string and the commands you type& include a space a'ter the =& like so(

41=>[>e[1m? =

nd i' you want the tet you type to !e a di''erent color& say& !lack& set that a'ter the prompt& like so(

41=>[>e[m?>[>e[!m =




The Top Ten Command Window Tips Page )

#ow& once you,ve got the hang o' the colors& include the rest o' the prompt that you so painstakingly constructed(

41=>[>e[m[>(@>h >w] %(de< >[>e[!m=

nd you,re all set with a customized prompt string that very well may !e a horse o' a di''erent color.

=" 4ccess root insie the 0o''an Winow="/" 0hange to root insie the co''an winowEou can change to root a'ter opening a command window in one o' two ways. The 'irst is !y using the :su; command(

[whil@freedom whil]$ s(4assword:[root@freedom whil]0

#ote that you9re still in the )home)whil directory& !ut now you9re root. 3Oe'erring !ack to the 'irst item& you9ll note that thetitle !ar has also changed& which means you have :godlike; powers. Eou can make any change you want to the system& installso'tware& delete 'iles& get into anyone else9s home directory& and so on. This also means& as *9ve said !e'ore& that you can dotons o' damage. 6or eample& :rm "r' ); will destroy every 'ile on your computer in a!out 'ive !limptoseconds.

The second way you can change to root is !y using the :su "; command(

[whil@freedom whil]$ s( -4assword:[root@freedom root] 0

*' you use this method& you9ll note that !oth the prompt string and the title !ar have changed. lso note that you9re now inthe )root directory 3which is the root user9s home directory. The reason that this is di''erent is that the :"; a'ter the :su;command !rings root9s environment along with it. What9s an environment> *t9s a group o' settings& such as the prompt& systemvaria!les& and so on& that !elong to a speci'ic user. The home directory& 'or eample& is one such setting& and the command" prompt string is another. These can !e di''erent 3and o'ten are 'or di''erent users.

When you use the :su; command& you9re Just gaining root privileges& !ut you9re still working in the original user9senvironmentBwith the original user9s path& prompt& home directory& and so on.

When you use the :su "; command& you switch your environment to that o' root& and that9s why you9re suddenly launchedinto root9s home directory. :su "; is short 'or :su "l; or :su ""login;& !y the way.

="1" 0hange fro' root $ack to the regular user in the co''an winow<nce you,re done with your root !usiness& you could close the Command Window and start up a new instance that would'eature the regular logged in user again& !ut that would !e time"consuming and unnecessary. *nstead& in order to go !ack to theregular user 'rom root& simply issue the :eit; command.

<' course& that might !e too much work 'or you. Eou can also type ctrl"d& which enters the ,eit, command and pressesAnter 'or you.

>" 0o''ans are sensiti%e ? case*sensiti%e& that is<ne command is :ls; 3list. Type :ls; at the command prompt& and you9ll get a directory listing. Type :%S; 3or :lS; or :%s;and you9ll get a response like this( :"!ash( %S( command not 'ound.;

@" o%e through co''an historyEou can scroll through command history !y using the up and down arrow keys. Eou can also type :history n; where ,n, is anum!er to display the last ,n, commands. Since !ash stores the last 7000 commands !y de'ault& you may want to include anum!er that is 'airly small 3perhaps less than the num!er o' rows in your command window.

histor 1!

<nce the history 'ile gets too !ig 'or you to com'orta!ly navigate through it&

histor -c




The Top Ten Command Window Tips Page E

will clear the history list !y deleting all entries.

/A" String co'pletionDressing the Ta! key will complete strings. s you saw in Chapter 7& you can use the Ta! key to complete a long 'ile nameinstead o' typing it 3and creating typos. To try this out i' you didn9t go through Chapter 7& switch to a directory that contains a !unch o' long 'ile names. *' you created a :zips; directory under your home directory in order to save zips and rpms that you9ve

downloaded& your zips directory might look something like this(

fp-li)(x-ws.rpm moilla-i"8"-pc-li)(x-)(-1."-i)staller.tar.rh9.messe)er-1.!.-1.i8".rpm rp8.li)(x2!.li,c".i8".cs2.rpm r'9Bli,c"Bi8"Bcs2.t C#ware-wor&statio)-.!.5-"!!.i8".rpm xmms-mi&mod-1.2.8-1.i8".rpm xmms-mp-1.2.8-.2.fr.i8".rpm

Suppose you wanted to run the :rpm; command on the PWare rpm package instead o' doing so through a graphical 'ilemanager. ccording to the PWare documentation& the command would look something like this(

rpm -Dh' C#ware-ExxxF.rpm

where the QR is the string :workstation"4.0."00.iU;. Eou certainly don9t want to type all o' those num!ers and periodsand hyphens. *nstead& you can type this(

rpm -Dh' C#

and then press the Ta! key. The string will !e epanded to this(

rpm -Dh' C#ware-wor&statio)-.!.5-"!!.i8".rpm

and the cursor will !e sitting at the end o' the line& waiting 'or you to make additional edits8 or you can simply press the Anter key to eecute the command.

The only caveat is that you have to type enough o' the string that the shell will !e a!le to uni+uely identi'y the 'ile you9reinterested in. *' you didn,t type enough to identi'y the 'ile& the amount that is matched will display& and then you can continuetyping until you get enough to make another uni+ue match.

//" ultiple co''an winowsEou can have multiple command windows open at the same time. This is handy 'or several reasons. The 'irst is that somecommands take over the command window& disa!ling it 'or any other use until the command is 'inished. 6or eample& i' youwant to edit a con'iguration 'ile& you can call gedit 'rom within a command window& like so(

edit /etc/fsta,

However& as long as gedit is running& you don9t have access to the command window that spawned the editor session. *' you want to run another command& you need to open a second command window.

The second reason to open multiple command windows is so you can do something as root without logging in as root. *' you9ve already got one command window open as your day"to"day user& you don9t have to close it. Vust open a secondcommand window and change to root in that window.

/1" 0o''an winow attri$utesEou can change the attri!utes o' a command window. The collection o' a command window9s attri!utes make up its :pro'ile&;and you can create multiple pro'iles& each o' which is used !y a di''erent user. This is particularly use'ul when you need to runone command window as root. Sure& the prompt changes& !ut it9s easy 3particularly as your eyes pass a certain vintage& likemine to miss that small visual clue. 3That,s why * also change my root command prompt to !e radically di''erent 'rom allothers.

To create a new pro'ile 'or a command window& select 6ile @ #ew Dro'ile 3see Figure 1.




The Top Ten Command Window Tips Page F

Figure 1. The New Profile dialog allows you to create a new profile,and optionally base it on an eisting profile.

Eou can also select Adit @ Dro'iles to open the Adit Dro'iles dialog 3Figure 2& and then click the #ew !utton to open the #ew Dro'ile dialog as shown in 6igure 7.

Figure 2 . The !dit Profiles dialog allows you to manage multiple profiles.

The #ew Dro'ile dialog de'aults to creating a new pro'ile !ased on the de'ault pro'ile in the system& !ut i' you9ve alreadycreated di''erent pro'iles& you9ll !e a!le to create a new pro'ile !ased on one o' them as well.

/ltimately& the #ew Dro'ile dialog doesn9t do anything terri!ly interesting. *t9s the Aditing Dro'ile dialog& shown inFigure 3& that holds all the action.




The Top Ten Command Window Tips Page10

Figure 3. The !diting Profile dialog contains si tabs of various attributes that describe the profile being edited.

Eou can also get to the Aditing Dro'ile dialog !y selecting Adit @ Current Dro'ile& or Adit @ Adit Dro'iles& and then selectingthe pro'ile o' interest and clicking the Adit !utton. <r you can right"click in the command window and select Adit CurrentDro'ile 'rom the resulting contet menu.

<n the eneral ta!& the pro'ile icon is the image that displays in the panel when you have a command window running.Eou pro!a!ly don9t want to change the 'ont& since the de'ault choice& monospace 72& looks okay and renders 'ied"pitch stringsnicely. Changing to a proportional 'ont such as rial can make it nearly impossi!le to distinguish !etween certain characters3the lowercase letter :l; and a num!er :7;& 'or eample.

<n the Title and Command ta!& you can control what shows up in the title !ar. Choices include the name o' the pro'ile invarious com!inations& with the de'ault string o' :username& hostname& and current directory.;

/6" Where to go for 'ore infor'ationThis 'ree whitepaper is pu!lished and distri!uted !y Hentzenwerke Du!lishing& *nc. We have the largest lists o' :oving to%inu;& <pen<''ice.org& and Pisual 6oDro !ooks on the planet.

We also have oodles o' 'ree whitepapers on our we!site and more are !eing added regularly. <ur Dre'erred Customer mailing list gets !i"monthly announcements o' new whitepapers 3and gets discounts on our !ooks& 'irst crack at special deals&and other stu'' as we think o' it.

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If ou found this whitepaper helpful! chec" out these #ent$enwer"e %ublishing boo"s as well:

&inux Transfer for 'indows( )etwor" *d+ins:

* road+ap for building a &inux file and print ser,er

ichael ang

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