Added gitignore entries needed to ignore derived objects generated from full build...

[bash.git] / doc / article.ps

%!PS-Adobe-3.0
%%Creator: groff version 1.16.1
%%CreationDate: Mon Nov 19 13:06:55 2001
%%DocumentNeededResources: font Times-Bold
%%+ font Times-Italic
%%+ font Times-Roman
%%+ font Courier
%%DocumentSuppliedResources: procset grops 1.16 1
%%Pages: 11
%%PageOrder: Ascend
%%Orientation: Portrait
%%EndComments
%%BeginProlog
%%BeginResource: procset grops 1.16 1
/setpacking where{
pop
currentpacking
true setpacking
}if
/grops 120 dict dup begin
/SC 32 def
/A/show load def
/B{0 SC 3 -1 roll widthshow}bind def
/C{0 exch ashow}bind def
/D{0 exch 0 SC 5 2 roll awidthshow}bind def
/E{0 rmoveto show}bind def
/F{0 rmoveto 0 SC 3 -1 roll widthshow}bind def
/G{0 rmoveto 0 exch ashow}bind def
/H{0 rmoveto 0 exch 0 SC 5 2 roll awidthshow}bind def
/I{0 exch rmoveto show}bind def
/J{0 exch rmoveto 0 SC 3 -1 roll widthshow}bind def
/K{0 exch rmoveto 0 exch ashow}bind def
/L{0 exch rmoveto 0 exch 0 SC 5 2 roll awidthshow}bind def
/M{rmoveto show}bind def
/N{rmoveto 0 SC 3 -1 roll widthshow}bind def
/O{rmoveto 0 exch ashow}bind def
/P{rmoveto 0 exch 0 SC 5 2 roll awidthshow}bind def
/Q{moveto show}bind def
/R{moveto 0 SC 3 -1 roll widthshow}bind def
/S{moveto 0 exch ashow}bind def
/T{moveto 0 exch 0 SC 5 2 roll awidthshow}bind def
/SF{
findfont exch
[exch dup 0 exch 0 exch neg 0 0]makefont
dup setfont
[exch/setfont cvx]cvx bind def
}bind def
/MF{
findfont
[5 2 roll
0 3 1 roll
neg 0 0]makefont
dup setfont
[exch/setfont cvx]cvx bind def
}bind def
/level0 0 def
/RES 0 def
/PL 0 def
/LS 0 def
/MANUAL{
statusdict begin/manualfeed true store end
}bind def
/PLG{
gsave newpath clippath pathbbox grestore
exch pop add exch pop
}bind def
/BP{
/level0 save def
1 setlinecap
1 setlinejoin
72 RES div dup scale
LS{
90 rotate
}{
0 PL translate
}ifelse
1 -1 scale
}bind def
/EP{
level0 restore
showpage
}bind def
/DA{
newpath arcn stroke
}bind def
/SN{
transform
.25 sub exch .25 sub exch
round .25 add exch round .25 add exch
itransform
}bind def
/DL{
SN
moveto
SN
lineto stroke
}bind def
/DC{
newpath 0 360 arc closepath
}bind def
/TM matrix def
/DE{
TM currentmatrix pop
translate scale newpath 0 0 .5 0 360 arc closepath
TM setmatrix
}bind def
/RC/rcurveto load def
/RL/rlineto load def
/ST/stroke load def
/MT/moveto load def
/CL/closepath load def
/FL{
currentgray exch setgray fill setgray
}bind def
/BL/fill load def
/LW/setlinewidth load def
/RE{
findfont
dup maxlength 1 index/FontName known not{1 add}if dict begin
{
1 index/FID ne{def}{pop pop}ifelse
}forall
/Encoding exch def
dup/FontName exch def
currentdict end definefont pop
}bind def
/DEFS 0 def
/EBEGIN{
moveto
DEFS begin
}bind def
/EEND/end load def
/CNT 0 def
/level1 0 def
/PBEGIN{
/level1 save def
translate
div 3 1 roll div exch scale
neg exch neg exch translate
0 setgray
0 setlinecap
1 setlinewidth
0 setlinejoin
10 setmiterlimit
[]0 setdash
/setstrokeadjust where{
pop
false setstrokeadjust
}if
/setoverprint where{
pop
false setoverprint
}if
newpath
/CNT countdictstack def
userdict begin
/showpage{}def
}bind def
/PEND{
clear
countdictstack CNT sub{end}repeat
level1 restore
}bind def
end def
/setpacking where{
pop
setpacking
}if
%%EndResource
%%IncludeResource: font Times-Bold
%%IncludeResource: font Times-Italic
%%IncludeResource: font Times-Roman
%%IncludeResource: font Courier
grops begin/DEFS 1 dict def DEFS begin/u{.001 mul}bind def end/RES 72
def/PL 792 def/LS false def/ENC0[/asciicircum/asciitilde/Scaron/Zcaron
/scaron/zcaron/Ydieresis/trademark/quotesingle/.notdef/.notdef/.notdef
/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef
/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef/.notdef
/.notdef/.notdef/space/exclam/quotedbl/numbersign/dollar/percent
/ampersand/quoteright/parenleft/parenright/asterisk/plus/comma/hyphen
/period/slash/zero/one/two/three/four/five/six/seven/eight/nine/colon
/semicolon/less/equal/greater/question/at/A/B/C/D/E/F/G/H/I/J/K/L/M/N/O
/P/Q/R/S/T/U/V/W/X/Y/Z/bracketleft/backslash/bracketright/circumflex
/underscore/quoteleft/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y
/z/braceleft/bar/braceright/tilde/.notdef/quotesinglbase/guillemotleft
/guillemotright/bullet/florin/fraction/perthousand/dagger/daggerdbl
/endash/emdash/ff/fi/fl/ffi/ffl/dotlessi/dotlessj/grave/hungarumlaut
/dotaccent/breve/caron/ring/ogonek/quotedblleft/quotedblright/oe/lslash
/quotedblbase/OE/Lslash/.notdef/exclamdown/cent/sterling/currency/yen
/brokenbar/section/dieresis/copyright/ordfeminine/guilsinglleft
/logicalnot/minus/registered/macron/degree/plusminus/twosuperior
/threesuperior/acute/mu/paragraph/periodcentered/cedilla/onesuperior
/ordmasculine/guilsinglright/onequarter/onehalf/threequarters
/questiondown/Agrave/Aacute/Acircumflex/Atilde/Adieresis/Aring/AE
/Ccedilla/Egrave/Eacute/Ecircumflex/Edieresis/Igrave/Iacute/Icircumflex
/Idieresis/Eth/Ntilde/Ograve/Oacute/Ocircumflex/Otilde/Odieresis
/multiply/Oslash/Ugrave/Uacute/Ucircumflex/Udieresis/Yacute/Thorn
/germandbls/agrave/aacute/acircumflex/atilde/adieresis/aring/ae/ccedilla
/egrave/eacute/ecircumflex/edieresis/igrave/iacute/icircumflex/idieresis
/eth/ntilde/ograve/oacute/ocircumflex/otilde/odieresis/divide/oslash
/ugrave/uacute/ucircumflex/udieresis/yacute/thorn/ydieresis]def
/Courier@0 ENC0/Courier RE/Times-Roman@0 ENC0/Times-Roman RE
/Times-Italic@0 ENC0/Times-Italic RE/Times-Bold@0 ENC0/Times-Bold RE
%%EndProlog
%%Page: 1 1
%%BeginPageSetup
BP
%%EndPageSetup
/F0 12/Times-Bold@0 SF(Bash \255 The GNU shell*)227.904 123 Q/F1 10
/Times-Italic@0 SF(Chet Rame)263.85 147 Q(y)-.3 E(Case W)221.72 159 Q
(estern Reserve Univer)-.92 E(sity)-.1 E -.15(ch)250.425 171 S
(et@po.cwru.edu).15 E/F2 10/Times-Bold@0 SF 2.5(1. Intr)72 207 R
(oduction)-.18 E(Bash)97 222.6 Q/F3 10/Times-Roman@0 SF .904
(is the shell, or command language interpreter)3.404 F 3.404(,t)-.4 G
.904(hat will appear in the GNU operating system.)-3.404 F 1.075
(The name is an acron)72 234.6 R 1.075(ym for the \231Bourne-Ag)-.15 F
1.075(ain SHell\232, a pun on Ste)-.05 F 1.375 -.15(ve B)-.25 H 1.075
(ourne, the author of the direct).15 F .206(ancestor of the current)72
246.6 R/F4 8/Times-Roman@0 SF(UNIX)2.706 E F3 2.706<ae73>C(hell)-2.706 E
F1(/bin/sh)2.706 E F3 2.706(,w)C .205(hich appeared in the Se)-2.706 F
-.15(ve)-.25 G .205(nth Edition Bell Labs Research v).15 F(er)-.15 E(-)
-.2 E(sion of)72 258.6 Q/F5 9/Times-Roman@0 SF(UNIX)2.5 E F3(.)A .387
(Bash is an)97 274.2 R F2(sh)2.887 E F3 .387
(\255compatible shell that incorporates useful features from the K)B
.388(orn shell \()-.35 F F2(ksh)A F3 2.888(\)a)C .388(nd the C)-2.888 F
.023(shell \()72 286.2 R F2(csh)A F3 .023
(\), described later in this article.)B .022
(It is ultimately intended to be a conformant implementation of the)
5.022 F 3.568(IEEE POSIX Shell and Utilities speci\214cation \(IEEE W)72
298.2 R 3.568(orking Group 1003.2\).)-.8 F 3.569(It of)8.569 F 3.569
(fers functional)-.25 F(impro)72 310.2 Q -.15(ve)-.15 G(ments o).15 E
-.15(ve)-.15 G 2.5(rs).15 G 2.5(hf)-2.5 G(or both interacti)-2.5 E .3
-.15(ve a)-.25 H(nd programming use.).15 E .697
(While the GNU operating system will most lik)97 325.8 R .697
(ely include a v)-.1 F .697(ersion of the Berk)-.15 F(ele)-.1 E 3.197
(ys)-.15 G .696(hell csh, Bash)-3.197 F .015(will be the def)72 337.8 R
.015(ault shell.)-.1 F(Lik)5.015 E 2.515(eo)-.1 G .015(ther GNU softw)
-2.515 F .016(are, Bash is quite portable.)-.1 F .016
(It currently runs on nearly e)5.016 F -.15(ve)-.25 G(ry).15 E -.15(ve)
72 349.8 S .523(rsion of).15 F F4(UNIX)3.023 E F3 .523(and a fe)3.023 F
3.023(wo)-.25 G .523
(ther operating systems \255 an independently-supported port e)-3.023 F
.523(xists for OS/2, and)-.15 F .706
(there are rumors of ports to DOS and W)72 361.8 R(indo)-.4 E .706
(ws NT)-.25 F 5.706(.P)-.74 G .706(orts to)-5.706 F F5(UNIX)3.206 E F3
(-lik)A 3.206(es)-.1 G .706(ystems such as QNX and Minix)-3.206 F
(are part of the distrib)72 373.8 Q(ution.)-.2 E .405
(The original author of Bash w)97 389.4 R .405(as Brian F)-.1 F .405
(ox, an emplo)-.15 F .405(yee of the Free Softw)-.1 F .405(are F)-.1 F
2.905(oundation. The)-.15 F(cur)2.905 E(-)-.2 E(rent de)72 401.4 Q -.15
(ve)-.25 G(loper and maintainer is Chet Rame).15 E 1.3 -.65(y, a v)-.15
H(olunteer who w).45 E(orks at Case W)-.1 E(estern Reserv)-.8 E 2.5(eU)
-.15 G(ni)-2.5 E -.15(ve)-.25 G(rsity).15 E(.)-.65 E F2 2.5(2. What')72
425.4 R 2.5(sP)-.37 G(OSIX, anyway?)-2.5 E F1(POSIX)97 441 Q F3 .343
(is a name originally coined by Richard Stallman for a f)2.843 F .343
(amily of open system standards based)-.1 F(on)72 453 Q F5(UNIX)3.24 E
F3 5.74(.T)C .74(here are a number of aspects of)-5.74 F F5(UNIX)3.24 E
F3 .74(under consideration for standardization, from the basic)3.24 F
.192(system services at the system call and C library le)72 465 R -.15
(ve)-.25 G 2.692(lt).15 G 2.692(oa)-2.692 G .192
(pplications and tools to system administration and)-2.692 F 2.5
(management. Each)72 477 R(area of standardization is assigned to a w)
2.5 E(orking group in the 1003 series.)-.1 E 2.814
(The POSIX Shell and Utilities standard has been de)97 492.6 R -.15(ve)
-.25 G 2.814(loped by IEEE W).15 F 2.813(orking Group 1003.2)-.8 F .254
(\(POSIX.2\).\210 It concentrates on the command interpreter interf)72
504.6 R .253(ace and utility programs commonly e)-.1 F -.15(xe)-.15 G
(cuted).15 E 1.112(from the command line or by other programs.)72 516.6
R 1.112(An initial v)6.112 F 1.113
(ersion of the standard has been appro)-.15 F -.15(ve)-.15 G 3.613(da)
.15 G(nd)-3.613 E .365(published by the IEEE, and w)72 528.6 R .365
(ork is currently underw)-.1 F .365(ay to update it.)-.1 F .365
(There are four primary areas of w)5.365 F(ork)-.1 E
(in the 1003.2 standard:)72 540.6 Q 21.5<8341>72 556.2 S .835
(spects of the shell')-21.5 F 3.335(ss)-.55 G .835
(yntax and command language.)-3.335 F 3.335(An)5.835 G .835
(umber of special b)-3.335 F .835(uiltins such as)-.2 F F2(cd)3.335 E F3
(and)3.335 E F2(exec)97 568.2 Q F3 .545(are being speci\214ed as part o\
f the shell, since their functionality usually cannot be implemented)
3.046 F(by a separate e)97 580.2 Q -.15(xe)-.15 G(cutable;).15 E 21.5
<8341>72 595.8 S .926
(set of utilities to be called by shell scripts and applications.)
-18.074 F .927(Examples are programs lik)5.927 F(e)-.1 E F1 .927
(sed, tr)3.427 F(,)-1.11 E F3(and)97 607.8 Q F1(awk.)2.797 E F3 .297
(Utilities commonly implemented as shell b)5.297 F .296
(uiltins are described in this section, such as)-.2 F F2(test)2.796 E F3
(and)97 619.8 Q F2(kill)3.422 E F3 5.922(.A)C 3.422(ne)-5.922 G .922
(xpansion of this section')-3.572 F 3.423(ss)-.55 G .923
(cope, termed the User Portability Extension, or UPE, has)-3.423 F
(standardized interacti)97 631.8 Q .3 -.15(ve p)-.25 H(rograms such as)
.15 E F1(vi)2.5 E F3(and)2.5 E F1(mailx;)2.5 E F3 21.5<8341>72 647.4 S
.288(group of functional interf)-18.712 F .287(aces to services pro)-.1
F .287(vided by the shell, such as the traditional)-.15 F/F6 10
/Courier@0 SF(system\(\))2.787 E F3 3.289(Cl)97 659.4 S .789
(ibrary function.)-3.289 F .789(There are functions to perform shell w)
5.789 F .789(ord e)-.1 F .79(xpansions, perform \214lename e)-.15 F
(xpan-)-.15 E .324(sion \()97 671.4 R F1(globbing)A F3 .324
(\), obtain v)B .323(alues of POSIX.2 system con\214guration v)-.25 F
.323(ariables, retrie)-.25 F .623 -.15(ve v)-.25 H .323(alues of en)-.1
F(viron-)-.4 E(ment v)97 683.4 Q(ariables \()-.25 E F6(getenv\(\))A F3
(\), and other services;).833 E .32 LW 144 691.4 72 691.4 DL F4
(*An earlier v)72 703.2 Q
(ersion of this article appeared in The Linux Journal.)-.12 E(\210IEEE,)
72 715 Q/F7 8/Times-Italic@0 SF 1.231(IEEE Standar)3.231 F 3.231(df)
-.296 G 1.231(or Information T)-3.231 F(ec)-.736 E(hnolo)-.12 E 1.231
(gy -- P)-.08 F 1.231(ortable Oper)-.64 F 1.232
(ating System Interface \(POSIX\) P)-.12 F 1.232(art 2:)-.64 F
(Shell and Utilities)72 725 Q F4 2(,1)C(992.)-2 E EP
%%Page: 2 2
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Roman@0 SF(-2-)282.17 48 Q 21.5<8341>72 84 S
(suite of \231de)-19 E -.15(ve)-.25 G(lopment\232 utilities such as).15
E/F1 10/Times-Italic@0 SF(c89)2.5 E F0(\(the POSIX.2 v)2.5 E(ersion of)
-.15 E F1(cc)2.5 E F0(\), and)A F1(yacc.)2.5 E F0 .483
(Bash is concerned with the aspects of the shell')97 99.6 R 2.983(sb)
-.55 G(eha)-2.983 E .484(vior de\214ned by POSIX.2.)-.2 F .484
(The shell command)5.484 F 1.439
(language has of course been standardized, including the basic \215o)72
111.6 R 3.938(wc)-.25 G 1.438(ontrol and program e)-3.938 F -.15(xe)-.15
G 1.438(cution con-).15 F 1.284
(structs, I/O redirection and pipelining, ar)72 123.6 R 1.284
(gument handling, v)-.18 F 1.284(ariable e)-.25 F 1.284
(xpansion, and quoting.)-.15 F(The)6.285 E F1(special)3.785 E F0 -.2(bu)
72 135.6 S .676
(iltins, which must be implemented as part of the shell to pro).2 F .676
(vide the desired functionality)-.15 F 3.176(,a)-.65 G .676
(re speci\214ed)-3.176 F .7(as being part of the shell; e)72 147.6 R .7
(xamples of these are)-.15 F/F2 10/Times-Bold@0 SF -2.3 -.15(ev a)3.201
H(l).15 E F0(and)3.201 E F2(export)3.201 E F0 5.701(.O)C .701
(ther utilities appear in the sections of)-5.701 F .256(POSIX.2 not de)
72 159.6 R -.2(vo)-.25 G .256(ted to the shell which are commonly \(and\
 in some cases must be\) implemented as b).2 F(uiltin)-.2 E .213
(commands, such as)72 171.6 R F2 -.18(re)2.713 G(ad).18 E F0(and)2.713 E
F2(test)2.713 E F0 5.213(.P)C .213
(OSIX.2 also speci\214es aspects of the shell')-5.213 F 2.713(si)-.55 G
(nteracti)-2.713 E .513 -.15(ve b)-.25 H(eha).15 E .214(vior as part)-.2
F .598(of the UPE, including job control and command line editing.)72
183.6 R .598(Interestingly enough, only)5.598 F F1(vi)3.098 E F0 .598
(-style line edit-)B(ing commands ha)72 195.6 Q .3 -.15(ve b)-.2 H
(een standardized;).15 E F1(emacs)2.5 E F0
(editing commands were left out due to objections.)2.5 E 1.128
(While POSIX.2 includes much of what the shell has traditionally pro)97
211.2 R 1.129(vided, some important things)-.15 F(ha)72 223.2 Q .344
-.15(ve b)-.2 H .044(een omitted as being \231be).15 F .044
(yond its scope.)-.15 F 5.043<9a54>-.7 G .043
(here is, for instance, no mention of a dif)-5.043 F .043
(ference between a)-.25 F F1(lo)72 235.2 Q(gin)-.1 E F0 1.445
(shell and an)3.945 F 3.945(yo)-.15 G 1.445(ther interacti)-3.945 F
1.745 -.15(ve s)-.25 H 1.446
(hell \(since POSIX.2 does not specify a login program\).).15 F 1.446
(No \214x)6.446 F(ed)-.15 E(startup \214les are de\214ned, either \255 \
the standard does not mention)72 247.2 Q F1(.pr)2.5 E(o\214le)-.45 E F0
(.)A F2 2.5(3. Basic)72 271.2 R(Bash featur)2.5 E(es)-.18 E F0 1.448
(Since the Bourne shell pro)97 286.8 R 1.448
(vides Bash with most of its philosophical underpinnings, Bash inherits)
-.15 F .64(most of its features and functionality from sh.)72 298.8 R
.641(Bash implements all of the traditional sh \215o)5.641 F 3.141(wc)
-.25 G .641(ontrol con-)-3.141 F .8(structs \()72 310.8 R F1(for)A F0(,)
A F1(if)3.3 E F0(,)A F1(while)3.3 E F0 3.3(,e)C 3.3(tc.\). All)-3.3 F
.799(of the Bourne shell b)3.3 F .799
(uiltins, including those not speci\214ed in the POSIX.2)-.2 F .536
(standard, appear in Bash.)72 322.8 R(Shell)5.536 E F1(functions)3.036 E
F0 3.036(,i)C .536(ntroduced in the SVR2 v)-3.036 F .537
(ersion of the Bourne shell, are similar)-.15 F .779
(to shell scripts, b)72 334.8 R .779
(ut are de\214ned using a special syntax and are e)-.2 F -.15(xe)-.15 G
.779(cuted in the same process as the calling).15 F 2.841(shell. Bash)72
346.8 R .341(has shell functions which beha)2.841 F .641 -.15(ve i)-.2 H
2.841(naf).15 G .341(ashion upw)-2.941 F .342
(ard-compatible with sh functions.)-.1 F .342(There are)5.342 F 1.447
(certain shell v)72 358.8 R 1.446
(ariables that Bash interprets in the same w)-.25 F 1.446
(ay as sh, such as)-.1 F F2(PS1)3.946 E F0(,)A F2(IFS)3.946 E F0 3.946
(,a)C(nd)-3.946 E F2 -.74(PA)3.946 G(TH)-.21 E F0 6.446(.B)C(ash)-6.446
E 1.423(implements essentially the same grammar)72 370.8 R 3.924(,p)-.4
G 1.424(arameter and v)-3.924 F 1.424(ariable e)-.25 F 1.424
(xpansion semantics, redirection, and)-.15 F 1.06
(quoting as the Bourne shell.)72 382.8 R 1.06(Where dif)6.06 F 1.06
(ferences appear between the POSIX.2 standard and traditional sh)-.25 F
(beha)72 394.8 Q(vior)-.2 E 2.5(,B)-.4 G(ash follo)-2.5 E(ws POSIX.)-.25
E 1.608(The K)97 410.4 R 1.608(orn Shell \()-.35 F F2(ksh)A F0 4.108
(\)i)C 4.108(sad)-4.108 G 1.608
(escendent of the Bourne shell written at A)-4.108 F 1.609
(T&T Bell Laboratories by)-1.11 F(Da)72 422.4 Q 1.059(vid K)-.2 F 3.559
(orn\207. It)-.35 F(pro)3.559 E 1.059
(vides a number of useful features that POSIX and Bash ha)-.15 F 1.359
-.15(ve a)-.2 H 3.558(dopted. Man).15 F 3.558(yo)-.15 G 3.558(ft)-3.558
G(he)-3.558 E(interacti)72 434.4 Q 1.312 -.15(ve f)-.25 H 1.012
(acilities in POSIX.2 ha).05 F 1.312 -.15(ve t)-.2 H 1.012
(heir roots in the ksh: for e).15 F 1.013
(xample, the POSIX and ksh job control)-.15 F -.1(fa)72 446.4 S .513
(cilities are nearly identical. Bash includes features from the K).1 F
.513(orn Shell for both interacti)-.35 F .813 -.15(ve u)-.25 H .513
(se and shell).15 F 3.905(programming. F)72 458.4 R 1.405
(or programming, Bash pro)-.15 F 1.405(vides v)-.15 F 1.405
(ariables such as)-.25 F F2(RANDOM)3.905 E F0(and)3.905 E F2(REPL)3.905
E(Y)-.92 E F0 3.905(,t)C(he)-3.905 E F2(typeset)3.905 E F0 -.2(bu)72
470.4 S .398(iltin, the ability to remo).2 F .698 -.15(ve s)-.15 H .398
(ubstrings from v).15 F .398
(ariables based on patterns, and shell arithmetic.)-.25 F F2(RANDOM)
5.397 E F0 -.15(ex)72 482.4 S .489
(pands to a random number each time it is referenced; assigning a v).15
F .49(alue to)-.25 F F2(RANDOM)2.99 E F0 .49(seeds the random)2.99 F
.055(number generator)72 494.4 R(.)-.55 E F2(REPL)5.055 E(Y)-.92 E F0
.054(is the def)2.554 F .054(ault v)-.1 F .054(ariable used by the)-.25
F F2 -.18(re)2.554 G(ad).18 E F0 -.2(bu)2.554 G .054(iltin when no v).2
F .054(ariable names are sup-)-.25 F .742(plied as ar)72 506.4 R 3.243
(guments. The)-.18 F F2(typeset)3.243 E F0 -.2(bu)3.243 G .743
(iltin is used to de\214ne v).2 F .743(ariables and gi)-.25 F 1.043 -.15
(ve t)-.25 H .743(hem attrib).15 F .743(utes such as)-.2 F F2 -.18(re)
3.243 G(ad-).18 E(only)72 518.4 Q F0 5.512(.B)C .512
(ash arithmetic allo)-5.512 F .512(ws the e)-.25 F -.25(va)-.25 G .511
(luation of an e).25 F .511
(xpression and the substitution of the result.)-.15 F .511(Shell v)5.511
F(ari-)-.25 E .222
(ables may be used as operands, and the result of an e)72 530.4 R .222
(xpression may be assigned to a v)-.15 F 2.722(ariable. Nearly)-.25 F
.222(all of)2.722 F(the operators from the C language are a)72 542.4 Q
-.25(va)-.2 G(ilable, with the same precedence rules:).25 E/F3 10
/Courier@0 SF 6($e)97 560.4 S(cho $\(\(3 + 5 * 32\)\))-6 E(163)97 572.4
Q F0 -.15(Fo)72 594 S 3.24(ri).15 G(nteracti)-3.24 E 1.04 -.15(ve u)-.25
H .74(se, Bash implements ksh-style aliases and b).15 F .74
(uiltins such as)-.2 F F2(fc)3.24 E F0 .74(\(discussed belo)3.24 F .74
(w\) and)-.25 F F2(jobs)3.24 E F0(.)A .291(Bash aliases allo)72 606 R
2.791(was)-.25 G .291(tring to be substituted for a command name.)-2.791
F(The)5.291 E 2.791(yc)-.15 G .291(an be used to create a mnemonic)
-2.791 F .568(for a)72 618 R/F4 9/Times-Roman@0 SF(UNIX)3.068 E F0 .568
(command name \()3.068 F F3 .568(alias del=rm)B F0 .568(\), to e)B .567
(xpand a single w)-.15 F .567(ord to a comple)-.1 F 3.067(xc)-.15 G .567
(ommand \()-3.067 F F3(alias)A .255
(news='xterm -g 80x45 -title trn -e trn -e -S1 -N &')72 630 R F0 .255
(\), or to ensure that a command)B(is in)72 642 Q -.2(vo)-.4 G -.1(ke).2
G 2.5(dw).1 G(ith a basic set of options \()-2.5 E F3
(alias ls="/bin/ls -F")A F0(\).)A .293(The C shell \()97 657.6 R F2(csh)
A F0 .293(\)\207, originally written by Bill Jo)B 2.792(yw)-.1 G .292
(hile at Berk)-2.792 F(ele)-.1 E 1.592 -.65(y, i)-.15 H 2.792(sw).65 G
.292(idely used and quite popular)-2.792 F 1.499(for its interacti)72
669.6 R 1.799 -.15(ve f)-.25 H 3.999(acilities. Bash).05 F 1.499
(includes a csh-compatible history e)3.999 F 1.5
(xpansion mechanism \(\231! history\232\),)-.15 F .019(brace e)72 681.6
R .018(xpansion, access to a stack of directories via the)-.15 F F2
(pushd)2.518 E F0(,)A F2(popd)2.518 E F0 2.518(,a)C(nd)-2.518 E F2(dirs)
2.518 E F0 -.2(bu)2.518 G .018(iltins, and tilde e).2 F(xpansion,)-.15 E
1.293(to generate users' home directories.)72 693.6 R -.35(Ti)6.294 G
1.294(lde e).35 F 1.294(xpansion has also been adopted by both the K)
-.15 F 1.294(orn Shell and)-.35 F .32 LW 144 708.2 72 708.2 DL/F5 8
/Times-Roman@0 SF(\207Morris Bolsk)72 720 Q 2(ya)-.12 G(nd Da)-2 E
(vid K)-.16 E(orn,)-.28 E/F6 8/Times-Italic@0 SF(The K)2 E
(ornShell Command and Pr)-.32 E -.08(og)-.36 G -.12(ra).08 G
(mming Langua).12 E -.08(ge)-.08 G F5 2(,P).08 G(rentice Hall, 1989.)-2
E EP
%%Page: 3 3
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Roman@0 SF(-3-)282.17 48 Q(POSIX.2.)72 84 Q .148
(There were certain areas in which POSIX.2 felt standardization w)97
99.6 R .149(as necessary)-.1 F 2.649(,b)-.65 G .149(ut no e)-2.849 F
.149(xisting imple-)-.15 F 1.598(mentation pro)72 111.6 R 1.598
(vided the proper beha)-.15 F(vior)-.2 E 6.598(.T)-.55 G 1.598(he w)
-6.598 F 1.597(orking group in)-.1 F -.15(ve)-.4 G 1.597
(nted and standardized functionality in).15 F .674
(these areas, which Bash implements.)72 123.6 R(The)5.674 E/F1 10
/Times-Bold@0 SF(command)3.174 E F0 -.2(bu)3.174 G .674(iltin w).2 F
.674(as in)-.1 F -.15(ve)-.4 G .674
(nted so that shell functions could be).15 F .996(written to replace b)
72 135.6 R .996(uiltins; it mak)-.2 F .996(es the capabilities of the b)
-.1 F .995(uiltin a)-.2 F -.25(va)-.2 G .995(ilable to the function.).25
F .995(The reserv)5.995 F(ed)-.15 E -.1(wo)72 147.6 S 1.731
(rd \231!\232 w).1 F 1.731(as added to ne)-.1 F -.05(ga)-.15 G 1.731
(te the return v).05 F 1.731(alue of a command or pipeline; it w)-.25 F
1.732(as nearly impossible to)-.1 F -.15(ex)72 159.6 S .286
(press \231if not x\232 cleanly using the sh language.).15 F .286
(There e)5.286 F .286(xist multiple incompatible implementations of the)
-.15 F F1(test)72 171.6 Q F0 -.2(bu)3.163 G .663
(iltin, which tests \214les for type and other attrib).2 F .664
(utes and performs arithmetic and string comparisons.)-.2 F .5
(POSIX considered none of these correct, so the standard beha)72 183.6 R
.5(vior w)-.2 F .5(as speci\214ed in terms of the number of)-.1 F(ar)72
195.6 Q .412(guments to the command.)-.18 F .412(POSIX.2 dictates e)
5.412 F .412(xactly what will happen when four or fe)-.15 F .412(wer ar)
-.25 F .412(guments are)-.18 F(gi)72 207.6 Q -.15(ve)-.25 G 5.01(nt).15
G(o)-5.01 E F1(test)5.01 E F0 5.01(,a)C 2.51(nd lea)-5.01 F -.15(ve)-.2
G 5.01(st).15 G 2.51(he beha)-5.01 F 2.51(vior unde\214ned when more ar)
-.2 F 2.51(guments are supplied.)-.18 F 2.51(Bash uses the)7.51 F
(POSIX.2 algorithm, which w)72 219.6 Q(as concei)-.1 E -.15(ve)-.25 G
2.5(db).15 G 2.5(yD)-2.5 G -.2(av)-2.5 G(id K).2 E(orn.)-.35 E F1 2.5
(3.1. F)72 243.6 R(eatur)-.25 E(es not in the Bour)-.18 E(ne Shell)-.15
E F0 .718(There are a number of minor dif)97 259.2 R .719
(ferences between Bash and the v)-.25 F .719
(ersion of sh present on most other)-.15 F -.15(ve)72 271.2 S .874
(rsions of).15 F/F2 9/Times-Roman@0 SF(UNIX)3.374 E F0 5.873(.T)C .873
(he majority of these are due to the POSIX standard, b)-5.873 F .873
(ut some are the result of Bash)-.2 F .386
(adopting features from other shells.)72 283.2 R -.15(Fo)5.386 G 2.886
(ri).15 G .386(nstance, Bash includes the ne)-2.886 F 2.886<7799>-.25 G
.386(!\232 reserv)-2.886 F .386(ed w)-.15 F .386(ord, the)-.1 F F1
(command)2.886 E F0 -.2(bu)72 295.2 S .116(iltin, the ability of the).2
F F1 -.18(re)2.616 G(ad).18 E F0 -.2(bu)2.615 G .115
(iltin to correctly return a line ending with a backslash, symbolic ar)
.2 F(guments)-.18 E .798(to the)72 307.2 R F1(umask)3.298 E F0 -.2(bu)
3.298 G .798(iltin, v).2 F .798(ariable substring remo)-.25 F -.25(va)
-.15 G .798(l, a w).25 F .799(ay to get the length of a v)-.1 F .799
(ariable, and the ne)-.25 F 3.299(wa)-.25 G(lgo-)-3.299 E(rithm for the)
72 319.2 Q F1(test)2.5 E F0 -.2(bu)2.5 G
(iltin from the POSIX.2 standard, none of which appear in sh.).2 E 1.225
(Bash also implements the \231$\(...\)\232 command substitution syntax,\
 which supersedes the sh `...` con-)97 334.8 R 2.851(struct. The)72
346.8 R .351(\231$\(...\)\232 construct e)2.851 F .351(xpands to the ou\
tput of the command contained within the parentheses, with)-.15 F .664
(trailing ne)72 358.8 R .664(wlines remo)-.25 F -.15(ve)-.15 G 3.164
(d. The).15 F .664(sh syntax is accepted for backw)3.164 F .664
(ards compatibility)-.1 F 3.164(,b)-.65 G .664
(ut the \231$\(...\)\232 form is)-3.364 F(preferred because its quoting\
 rules are much simpler and it is easier to nest.)72 370.8 Q .772
(The Bourne shell does not pro)97 386.4 R .772
(vide such features as brace e)-.15 F .772
(xpansion, the ability to de\214ne a v)-.15 F(ariable)-.25 E .283
(and a function with the same name, local v)72 398.4 R .282
(ariables in shell functions, the ability to enable and disable indi-)
-.25 F .547(vidual b)72 410.4 R .547
(uiltins or write a function to replace a b)-.2 F .547
(uiltin, or a means to e)-.2 F .547
(xport a shell function to a child pro-)-.15 F(cess.)72 422.4 Q .32
(Bash has closed a long-standing shell security hole by not using the)97
438 R F1($IFS)2.82 E F0 -.25(va)2.82 G .32(riable to split each w).25 F
(ord)-.1 E 1.254(read by the shell, b)72 450 R 1.254
(ut splitting only the results of e)-.2 F 1.255
(xpansion \(ksh and the 4.4 BSD sh ha)-.15 F 1.555 -.15(ve \214)-.2 H
-.15(xe).15 G 3.755(dt).15 G 1.255(his as)-3.755 F 2.907(well\). Useful)
72 462 R(beha)2.907 E .407(vior such as a means to abort e)-.2 F -.15
(xe)-.15 G .407(cution of a script read with the \231.).15 F 2.906<9a63>
-.7 G .406(ommand using the)-2.906 F F1 -.18(re)72 474 S(tur).18 E(n)
-.15 E F0 -.2(bu)2.742 G .242(iltin or automatically e).2 F .242
(xporting v)-.15 F .243(ariables in the shell')-.25 F 2.743(se)-.55 G
-.4(nv)-2.743 G .243(ironment to children is also not present).4 F .969
(in the Bourne shell.)72 486 R .968(Bash pro)5.968 F .968
(vides a much more po)-.15 F .968(werful en)-.25 F .968
(vironment for both interacti)-.4 F 1.268 -.15(ve u)-.25 H .968
(se and pro-).15 F(gramming.)72 498 Q F1 2.5(4. Bash-speci\214c)72 522 R
-.25(Fe)2.5 G(atur).25 E(es)-.18 E F0 .491(This section details a fe)97
537.6 R 2.991(wo)-.25 G 2.991(ft)-2.991 G .491(he features which mak)
-2.991 F 2.991(eB)-.1 G .491(ash unique.)-2.991 F .492(Most of them pro)
5.491 F .492(vide impro)-.15 F -.15(ve)-.15 G(d).15 E(interacti)72 549.6
Q 1.182 -.15(ve u)-.25 H .882(se, b).15 F .882(ut a fe)-.2 F 3.382(wp)
-.25 G .882(rogramming impro)-3.382 F -.15(ve)-.15 G .882
(ments are present as well.).15 F .882(Full descriptions of these fea-)
5.882 F(tures can be found in the Bash documentation.)72 561.6 Q F1 2.5
(4.1. Startup)72 585.6 R(Files)2.5 E F0 .161(Bash e)97 601.2 R -.15(xe)
-.15 G .161(cutes startup \214les dif).15 F .161
(ferently than other shells.)-.25 F .162(The Bash beha)5.161 F .162
(vior is a compromise between)-.2 F .29
(the csh principle of startup \214les with \214x)72 613.2 R .29
(ed names e)-.15 F -.15(xe)-.15 G .29
(cuted for each shell and the sh \231minimalist\232 beha).15 F(vior)-.2
E(.)-.55 E 2.955(An interacti)72 625.2 R 3.255 -.15(ve i)-.25 H 2.955
(nstance of Bash started as a login shell reads and e).15 F -.15(xe)-.15
G(cutes).15 E/F3 10/Times-Italic@0 SF(~/.bash_pr)5.456 E(o\214le)-.45 E
F0 2.956(\(the \214le)5.456 F .954(.bash_pro\214le in the user')72 637.2
R 3.454(sh)-.55 G .953(ome directory\), if it e)-3.454 F 3.453
(xists. An)-.15 F(interacti)3.453 E 1.253 -.15(ve n)-.25 H .953
(on-login shell reads and e).15 F -.15(xe)-.15 G(cutes).15 E F3
(~/.bashr)72 649.2 Q(c)-.37 E F0 5.641(.A)C(non-interacti)-2.5 E .942
-.15(ve s)-.25 H .642(hell \(one be).15 F .642(gun to e)-.15 F -.15(xe)
-.15 G .642(cute a shell script, for e).15 F .642
(xample\) reads no \214x)-.15 F .642(ed startup)-.15 F .342(\214le, b)72
661.2 R .342(ut uses the v)-.2 F .342(alue of the v)-.25 F(ariable)-.25
E F1($ENV)2.842 E F0 2.841(,i)C 2.841(fs)-2.841 G .341
(et, as the name of a startup \214le.)-2.841 F .341
(The ksh practice of read-)5.341 F(ing)72 673.2 Q F1($ENV)3.114 E F0
.614(for e)3.114 F -.15(ve)-.25 G .614(ry shell, with the accompan).15 F
.615(ying dif)-.15 F .615(\214culty of de\214ning the proper v)-.25 F
.615(ariables and functions)-.25 F .721(for interacti)72 685.2 R 1.021
-.15(ve a)-.25 H .721(nd non-interacti).15 F 1.021 -.15(ve s)-.25 H .721
(hells or ha).15 F .721(ving the \214le read only for interacti)-.2 F
1.02 -.15(ve s)-.25 H .72(hells, w).15 F .72(as considered)-.1 F .158
(too comple)72 697.2 R 2.658(x. Ease)-.15 F .158(of use w)2.658 F .158
(on out here.)-.1 F(Interestingly)5.158 E 2.658(,t)-.65 G .158(he ne)
-2.658 F .159(xt release of ksh will change to reading)-.15 F F1($ENV)
2.659 E .32 LW 144 705.2 72 705.2 DL/F4 8/Times-Roman@0 SF .559
(\207Bill Jo)72 717 R 1.599 -.52(y, A)-.08 H 2.559(nI).52 G .559
(ntroduction to the C Shell,)-2.559 F/F5 8/Times-Italic@0 SF .558
(UNIX User')2.558 F 2.558(sS)-.32 G .558(upplementary Documents)-2.558 F
F4 2.558(,U)C(ni)-2.558 E -.12(ve)-.2 G .558(rsity of California at).12
F(Berk)72 727 Q(ele)-.08 E 1.04 -.52(y, 1)-.12 H(986.).52 E EP
%%Page: 4 4
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Roman@0 SF(-4-)282.17 48 Q(only for interacti)72 84 Q .3
-.15(ve s)-.25 H(hells.).15 E/F1 10/Times-Bold@0 SF 2.5(4.2. New)72 108
R(Builtin Commands)2.5 E F0 1.02(There are a fe)97 123.6 R 3.52(wb)-.25
G 1.02(uiltins which are ne)-3.72 F 3.52(wo)-.25 G 3.52(rh)-3.52 G -2.25
-.2(av e)-3.52 H 1.02(been e)3.72 F 1.02(xtended in Bash.)-.15 F(The)
6.02 E F1(enable)3.52 E F0 -.2(bu)3.52 G 1.02(iltin allo).2 F(ws)-.25 E
-.2(bu)72 135.6 S .824(iltin commands to be turned on and of).2 F 3.324
(fa)-.25 G(rbitrarily)-3.324 E 5.824(.T)-.65 G 3.324(ou)-6.624 G .824
(se the v)-3.324 F .824(ersion of)-.15 F/F2 10/Times-Italic@0 SF(ec)
3.324 E(ho)-.15 E F0 .825(found in a user')3.324 F 3.325(ss)-.55 G
(earch)-3.325 E .625(path rather than the Bash b)72 147.6 R(uiltin,)-.2
E/F3 10/Courier@0 SF .625(enable -n echo)3.125 F F0(suf)3.125 E 3.125
(\214ces. The)-.25 F F1(help)3.124 E F0 -.2(bu)3.124 G .624(iltin pro).2
F .624(vides quick synopses)-.15 F .703(of the shell f)72 159.6 R .704
(acilities without requiring access to a manual page.)-.1 F F1(Builtin)
5.704 E F0 .704(is similar to)3.204 F F1(command)3.204 E F0 .704
(in that it)3.204 F .342(bypasses shell functions and directly e)72
171.6 R -.15(xe)-.15 G .342(cutes b).15 F .342(uiltin commands.)-.2 F
.342(Access to a csh-style stack of directories)5.342 F .072(is pro)72
183.6 R .073(vided via the)-.15 F F1(pushd)2.573 E F0(,)A F1(popd)2.573
E F0 2.573(,a)C(nd)-2.573 E F1(dirs)2.573 E F0 -.2(bu)2.573 G(iltins.).2
E F1(Pushd)5.073 E F0(and)2.573 E F1(popd)2.573 E F0 .073
(insert and remo)2.573 F .373 -.15(ve d)-.15 H .073(irectories from the)
.15 F 2.858(stack, respecti)72 195.6 R -.15(ve)-.25 G(ly).15 E 5.358(,a)
-.65 G(nd)-5.358 E F1(dirs)5.358 E F0 2.858(lists the stack contents.)
5.358 F 2.858(On systems that allo)7.858 F 5.358<778c>-.25 G 2.857
(ne-grained control of)-5.358 F 1.339(resources, the)72 207.6 R F1
(ulimit)3.839 E F0 -.2(bu)3.839 G 1.339
(iltin can be used to tune these settings.).2 F F1(Ulimit)6.34 E F0
(allo)3.84 E 1.34(ws a user to control, among)-.25 F 1.086
(other things, whether core dumps are to be generated, ho)72 219.6 R
3.586(wm)-.25 G 1.086(uch memory the shell or a child process is)-3.586
F(allo)72 231.6 Q .496(wed to allocate, and ho)-.25 F 2.996(wl)-.25 G
(ar)-2.996 E .496(ge a \214le created by a child process can gro)-.18 F
4.296 -.65(w. T)-.25 H(he).65 E F1(suspend)2.996 E F0 .497(command will)
2.997 F .744(stop the shell process when job control is acti)72 243.6 R
-.15(ve)-.25 G 3.243(;m).15 G .743(ost other shells do not allo)-3.243 F
3.243(wt)-.25 G(hemselv)-3.243 E .743(es to be stopped)-.15 F(lik)72
255.6 Q 2.717(et)-.1 G(hat.)-2.717 E F1 -.74(Ty)5.217 G(pe,).74 E F0
.217(the Bash answer to)2.717 F F1(which)2.717 E F0(and)2.717 E F1
(whence,)2.717 E F0(sho)2.717 E .218(ws what will happen when a w)-.25 F
.218(ord is typed as a)-.1 F(command:)72 267.6 Q F3 6($t)97 285.6 S
(ype export)-6 E(export is a shell builtin)97 297.6 Q 6($t)97 309.6 S
(ype -t export)-6 E(builtin)97 321.6 Q 6($t)97 333.6 S(ype bash)-6 E
(bash is /bin/bash)97 345.6 Q 6($t)97 357.6 S(ype cd)-6 E
(cd is a function)97 369.6 Q(cd \(\))97 381.6 Q({)97 393.6 Q
(builtin cd ${1+"$@"} && xtitle $HOST: $PWD)121 405.6 Q(})97 417.6 Q F0
-1.11(Va)72 439.2 S .682(rious modes tell what a command w)1.11 F .681
(ord is \(reserv)-.1 F .681(ed w)-.15 F .681(ord, alias, function, b)-.1
F .681(uiltin, or \214le\) or which v)-.2 F(er)-.15 E(-)-.2 E 1.15
(sion of a command will be e)72 451.2 R -.15(xe)-.15 G 1.15
(cuted based on a user').15 F 3.65(ss)-.55 G 1.15(earch path.)-3.65 F
1.15(Some of this functionality has been)6.15 F
(adopted by POSIX.2 and folded into the)72 463.2 Q F1(command)2.5 E F0
(utility)2.5 E(.)-.65 E F1 2.5(4.3. Editing)72 487.2 R(and Completion)
2.5 E F0 .682(One area in which Bash shines is command line editing.)97
502.8 R .682(Bash uses the)5.682 F F2 -.37(re)3.182 G(adline).37 E F0
.681(library to read and)3.181 F .942(edit lines when interacti)72 514.8
R -.15(ve)-.25 G 5.942(.R).15 G .942(eadline is a po)-5.942 F .942
(werful and \215e)-.25 F .942(xible input f)-.15 F .943
(acility that a user can con\214gure to)-.1 F(indi)72 526.8 Q .732
(vidual tastes.)-.25 F .732(It allo)5.732 F .732(ws lines to be edited \
using either emacs or vi commands, where those commands)-.25 F .2
(are appropriate.)72 538.8 R .2
(The full capability of emacs is not present \255 there is no w)5.2 F .2
(ay to e)-.1 F -.15(xe)-.15 G .2(cute a named command).15 F 1.15
(with M-x, for instance \255 b)72 550.8 R 1.15(ut the e)-.2 F 1.149
(xisting commands are more than adequate.)-.15 F 1.149
(The vi mode is compliant)6.149 F
(with the command line editing standardized by POSIX.2.)72 562.8 Q 1.69
(Readline is fully customizable.)97 578.4 R 1.691
(In addition to the basic commands and k)6.69 F 1.991 -.15(ey b)-.1 H
1.691(indings, the library).15 F(allo)72 590.4 Q .028
(ws users to de\214ne additional k)-.25 F .327 -.15(ey b)-.1 H .027
(indings using a startup \214le.).15 F(The)5.027 E F2(inputr)2.527 E(c)
-.37 E F0 .027(\214le, which def)2.527 F .027(aults to the \214le)-.1 F
F2(~/.inputr)72 602.4 Q(c)-.37 E F0 3.002(,i)C 3.002(sr)-3.002 G .503(e\
ad each time readline initializes, permitting users to maintain a consi\
stent interf)-3.002 F .503(ace across a)-.1 F .893(set of programs.)72
614.4 R .893(Readline includes an e)5.893 F .893(xtensible interf)-.15 F
.892(ace, so each program using the library can add its)-.1 F -.25(ow)72
626.4 S 3.56(nb).25 G 1.06(indable commands and program-speci\214c k)
-3.56 F 1.361 -.15(ey b)-.1 H 3.561(indings. Bash).15 F 1.061
(uses this f)3.561 F 1.061(acility to add bindings that)-.1 F
(perform history e)72 638.4 Q(xpansion or shell w)-.15 E(ord e)-.1 E
(xpansions on the current input line.)-.15 E .707
(Readline interprets a number of v)97 654 R .706
(ariables which further tune its beha)-.25 F(vior)-.2 E 5.706(.V)-.55 G
.706(ariables e)-6.816 F .706(xist to control)-.15 F .157
(whether or not eight-bit characters are directly read as input or con)
72 666 R -.15(ve)-.4 G .158(rted to meta-pre\214x).15 F .158(ed k)-.15 F
.458 -.15(ey s)-.1 H .158(equences \(a).15 F(meta-pre\214x)72 678 Q .082
(ed k)-.15 F .382 -.15(ey s)-.1 H .081(equence consists of the characte\
r with the eighth bit zeroed, preceded by the).15 F F2(meta-pr)2.581 E
(e\214x)-.37 E F0(character)72 690 Q 3.233(,u)-.4 G .733
(sually escape, which selects an alternate k)-3.233 F -.15(ey)-.1 G .734
(map\), to decide whether to output characters with).15 F .624
(the eighth bit set directly or as a meta-pre\214x)72 702 R .624(ed k)
-.15 F .924 -.15(ey s)-.1 H .623
(equence, whether or not to wrap to a ne).15 F 3.123(ws)-.25 G .623
(creen line)-3.123 F 1.196
(when a line being edited is longer than the screen width, the k)72 714
R -.15(ey)-.1 G 1.196(map to which subsequent k).15 F 1.496 -.15(ey b)
-.1 H(indings).15 E .531(should apply)72 726 R 3.031(,o)-.65 G 3.031(re)
-3.031 G -.15(ve)-3.281 G 3.031(nw).15 G .531
(hat happens when readline w)-3.031 F .531(ants to ring the terminal')
-.1 F 3.03(sb)-.55 G 3.03(ell. All)-3.03 F .53(of these v)3.03 F
(ariables)-.25 E EP
%%Page: 5 5
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Roman@0 SF(-5-)282.17 48 Q
(can be set in the inputrc \214le.)72 84 Q .284
(The startup \214le understands a set of C preprocessor)97 99.6 R(-lik)
-.2 E 2.785(ec)-.1 G .285(onditional constructs which allo)-2.785 F
2.785(wv)-.25 G(ariables)-3.035 E .12(or k)72 111.6 R .42 -.15(ey b)-.1
H .119(indings to be assigned based on the application using readline, \
the terminal currently being used, or).15 F .338(the editing mode.)72
123.6 R .338(Users can add program-speci\214c bindings to mak)5.338 F
2.838(et)-.1 G .338(heir li)-2.838 F -.15(ve)-.25 G 2.838(se).15 G 2.838
(asier: I)-2.838 F(ha)2.838 E .639 -.15(ve b)-.2 H .339(indings that).15
F(let me edit the v)72 135.6 Q(alue of)-.25 E/F1 10/Times-Bold@0 SF($P)
2.5 E -.95(AT)-.74 G(H).95 E F0(and double-quote the current or pre)2.5
E(vious w)-.25 E(ord:)-.1 E/F2 10/Courier@0 SF 6(#M)97 153.6 S
(acros that are convenient for shell interaction)-6 E($if Bash)97 165.6
Q 6(#e)97 177.6 S(dit the path)-6 E
("\\C-xp": "PATH=${PATH}\\e\\C-e\\C-a\\ef\\C-f")97 189.6 Q 6(#p)97 201.6
S(repare to type a quoted word -- insert open and close double)-6 E 6
(#q)97 213.6 S(uotes and move to just after the open quote)-6 E
("\\C-x\\"": "\\"\\"\\C-b")97 225.6 Q 6(#Q)97 237.6 S
(uote the current or previous word)-6 E("\\C-xq": "\\eb\\"\\ef\\"")97
249.6 Q($endif)97 261.6 Q F0 .322(There is a readline command to re-rea\
d the \214le, so users can edit the \214le, change some bindings, and b\
e)72 283.2 R(gin)-.15 E(to use them almost immediately)72 295.2 Q(.)-.65
E .851(Bash implements the)97 310.8 R F1(bind)3.351 E F0 -.2(bu)3.351 G
.851(iltin for more dyamic control of readline than the startup \214le \
permits.).2 F F1(Bind)72 322.8 Q F0 .25(is used in se)2.75 F -.15(ve)
-.25 G .25(ral w).15 F 2.75(ays. In)-.1 F/F3 10/Times-Italic@0 SF(list)
2.75 E F0 .25(mode, it can display the current k)2.75 F .55 -.15(ey b)
-.1 H .25(indings, list all the readline edit-).15 F .149(ing directi)72
334.8 R -.15(ve)-.25 G 2.649(sa).15 G -.25(va)-2.849 G .149
(ilable for binding, list which k).25 F -.15(ey)-.1 G 2.649(si).15 G
-1.9 -.4(nv o)-2.649 H .349 -.1(ke a g).4 H -2.15 -.25(iv e).1 H 2.65
(nd).25 G(irecti)-2.65 E -.15(ve)-.25 G 2.65(,o).15 G 2.65(ro)-2.65 G
.15(utput the current set of k)-2.65 F -.15(ey)-.1 G .042(bindings in a\
 format that can be incorporated directly into an inputrc \214le.)72
346.8 R(In)5.041 E F3(batc)2.541 E(h)-.15 E F0 .041
(mode, it reads a series of)2.541 F -.1(ke)72 358.8 S 2.858(yb)-.05 G
.359(indings directly from a \214le and passes them to readline.)-2.858
F .359(In its most common usage,)5.359 F F1(bind)2.859 E F0(tak)2.859 E
.359(es a sin-)-.1 F 1.117(gle string and passes it directly to readlin\
e, which interprets the line as if it had just been read from the)72
370.8 R(inputrc \214le.)72 382.8 Q(Both k)5 E .3 -.15(ey b)-.1 H
(indings and v).15 E(ariable assignments may appear in the string gi)
-.25 E -.15(ve)-.25 G 2.5(nt).15 G(o)-2.5 E F1(bind)2.5 E F0(.)A .53
(The readline library also pro)97 398.4 R .53(vides an interf)-.15 F .53
(ace for)-.1 F F3(wor)3.03 E 3.03(dc)-.37 G(ompletion)-3.03 E F0 5.53
(.W)C .53(hen the)-5.53 F F3(completion)3.03 E F0(character)3.03 E 1.261
(\(usually T)72 410.4 R 1.261(AB\) is typed, readline looks at the w)
-.93 F 1.26(ord currently being entered and computes the set of \214le-)
-.1 F .523(names of which the current w)72 422.4 R .523(ord is a v)-.1 F
.523(alid pre\214x.)-.25 F .524
(If there is only one possible completion, the rest of the)5.523 F .358
(characters are inserted directly)72 434.4 R 2.858(,o)-.65 G .358(therw\
ise the common pre\214x of the set of \214lenames is added to the curre\
nt)-2.858 F -.1(wo)72 446.4 S 3.199(rd. A).1 F .699(second T)3.199 F
.699(AB character entered immediately after a non-unique completion cau\
ses readline to list)-.93 F 1.814
(the possible completions; there is an option to ha)72 458.4 R 2.113
-.15(ve t)-.2 H 1.813(he list displayed immediately).15 F 6.813(.R)-.65
G 1.813(eadline pro)-6.813 F(vides)-.15 E .482
(hooks so that applications can pro)72 470.4 R .482
(vide speci\214c types of completion before the def)-.15 F .483
(ault \214lename completion)-.1 F .132(is attempted.)72 482.4 R .132
(This is quite \215e)5.132 F .132
(xible, though it is not completely user)-.15 F 2.632
(-programmable. Bash,)-.2 F .132(for e)2.632 F .132(xample, can)-.15 F
.37(complete \214lenames, command names \(including aliases, b)72 494.4
R .37(uiltins, shell reserv)-.2 F .37(ed w)-.15 F .37
(ords, shell functions, and)-.1 F -.15(exe)72 506.4 S .424
(cutables found in the \214le system\), shell v).15 F .424
(ariables, usernames, and hostnames.)-.25 F .423
(It uses a set of heuristics)5.424 F(that, while not perfect, is genera\
lly quite good at determining what type of completion to attempt.)72
518.4 Q F1 2.5(4.4. History)72 542.4 R F0 .144
(Access to the list of commands pre)97 558 R .144(viously entered \(the)
-.25 F F3 .144(command history)2.644 F F0 2.644(\)i)C 2.644(sp)-2.644 G
(ro)-2.644 E .144(vided jointly by Bash)-.15 F .078
(and the readline library)72 570 R 5.077(.B)-.65 G .077(ash pro)-5.077 F
.077(vides v)-.15 F .077(ariables \()-.25 F F1($HISTFILE)A F0(,)A F1
($HISTSIZE)2.577 E F0 2.577(,a)C(nd)-2.577 E F1($HISTCONTR)2.577 E(OL)
-.3 E F0 2.577(\)a)C(nd)-2.577 E(the)72 582 Q F1(history)2.89 E F0(and)
2.89 E F1(fc)2.89 E F0 -.2(bu)2.89 G .39
(iltins to manipulate the history list.).2 F .391(The v)5.391 F .391
(alue of)-.25 F F1($HISTFILE)2.891 E F0 .391(specifes the \214le where)
2.891 F .49(Bash writes the command history on e)72 594 R .489
(xit and reads it on startup.)-.15 F F1($HISTSIZE)5.489 E F0 .489
(is used to limit the number)2.989 F .642(of commands sa)72 606 R -.15
(ve)-.2 G 3.142(di).15 G 3.142(nt)-3.142 G .642(he history)-3.142 F(.)
-.65 E F1($HISTCONTR)5.642 E(OL)-.3 E F0(pro)3.142 E .642
(vides a crude form of control o)-.15 F -.15(ve)-.15 G 3.142(rw).15 G
.642(hich com-)-3.142 F .025(mands are sa)72 618 R -.15(ve)-.2 G 2.525
(do).15 G 2.525(nt)-2.525 G .025(he history list: a v)-2.525 F .025
(alue of)-.25 F F3(ignor)2.525 E(espace)-.37 E F0 .025(means to not sa)
2.525 F .324 -.15(ve c)-.2 H .024(ommands which be).15 F .024
(gin with a)-.15 F .927(space; a v)72 630 R .927(alue of)-.25 F F3
(ignor)3.427 E(edups)-.37 E F0 .927(means to not sa)3.427 F 1.228 -.15
(ve c)-.2 H .928(ommands identical to the last command sa).15 F -.15(ve)
-.2 G(d.).15 E F1($HIST)5.928 E(-)-.92 E(CONTR)72 642 Q(OL)-.3 E F0 -.1
(wa)3.778 G 3.778(sn).1 G(amed)-3.778 E F1($history_contr)3.778 E(ol)
-.18 E F0 1.278(in earlier v)3.778 F 1.278
(ersions of Bash; the old name is still accepted for)-.15 F(backw)72 654
Q .575(ards compatibility)-.1 F 5.575(.T)-.65 G(he)-5.575 E F1(history)
3.075 E F0 .575
(command can read or write \214les containing the history list and dis-)
3.075 F .167(play the current list contents.)72 666 R(The)5.167 E F1(fc)
2.667 E F0 -.2(bu)2.667 G .167(iltin, adopted from POSIX.2 and the K).2
F .167(orn Shell, allo)-.35 F .167(ws display and)-.25 F(re-e)72 678 Q
-.15(xe)-.15 G .58
(cution, with optional editing, of commands from the history list.).15 F
.58(The readline library of)5.58 F .58(fers a set of)-.25 F 1.255(comma\
nds to search the history list for a portion of the current input line \
or a string typed by the user)72 690 R(.)-.55 E(Finally)72 702 Q 2.535
(,t)-.65 G(he)-2.535 E F3(history)2.535 E F0(library)2.535 E 2.535(,g)
-.65 G .036(enerally incorporated directly into the readline library)
-2.535 F 2.536(,i)-.65 G .036(mplements a f)-2.536 F .036(acility for)
-.1 F 1.023(history recall, e)72 714 R 1.022(xpansion, and re-e)-.15 F
-.15(xe)-.15 G 1.022(cution of pre).15 F 1.022(vious commands v)-.25 F
1.022(ery similar to csh \(\231bang history\232, so)-.15 F
(called because the e)72 726 Q
(xclamation point introduces a history substitution\):)-.15 E EP
%%Page: 6 6
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Roman@0 SF(-6-)282.17 48 Q/F1 10/Courier@0 SF 6($e)97 84 S
(cho a b c d e)-6 E 6(abcde)97 96 S 6($!)97 108 S 6(!fghi)-6 G
(echo a b c d e f g h i)97 120 Q 6(abcdefghi)97 132 S 6($!)97 144 S(-2)
-6 E(echo a b c d e)97 156 Q 6(abcde)97 168 S 6($e)97 180 S(cho !-2:1-4)
-6 E(echo a b c d)97 192 Q 6(abcd)97 204 S F0 1.456
(The command history is only sa)72 225.6 R -.15(ve)-.2 G 3.957(dw).15 G
1.457(hen the shell is interacti)-3.957 F -.15(ve)-.25 G 3.957(,s).15 G
3.957(oi)-3.957 G 3.957(ti)-3.957 G 3.957(sn)-3.957 G 1.457(ot a)-3.957
F -.25(va)-.2 G 1.457(ilable for use by shell).25 F(scripts.)72 237.6 Q
/F2 10/Times-Bold@0 SF 2.5(4.5. New)72 261.6 R(Shell V)2.5 E(ariables)
-.92 E F0 .59(There are a number of con)97 277.2 R -.15(ve)-.4 G .589
(nience v).15 F .589(ariables that Bash interprets to mak)-.25 F 3.089
(el)-.1 G .589(ife easier)-3.089 F 5.589(.T)-.55 G .589(hese include)
-5.589 F F2(FIGNORE)72 289.2 Q F0 3.973(,w)C 1.473
(hich is a set of \214lename suf)-3.973 F<8c78>-.25 E 1.474
(es identifying \214les to e)-.15 F 1.474
(xclude when completing \214lenames;)-.15 F F2(HOSTTYPE)72 301.2 Q F0
2.932(,w)C .432
(hich is automatically set to a string describing the type of hardw)
-2.932 F .431(are on which Bash is cur)-.1 F(-)-.2 E .335(rently e)72
313.2 R -.15(xe)-.15 G(cuting;).15 E F2(command_oriented_history)2.835 E
F0 2.835(,w)C .335(hich directs Bash to sa)-2.835 F .635 -.15(ve a)-.2 H
.336(ll lines of a multiple-line com-).15 F 1.071(mand such as a)72
325.2 R/F3 10/Times-Italic@0 SF(while)3.571 E F0(or)3.571 E F3(for)3.571
E F0 1.071(loop in a single history entry)3.571 F 3.57(,a)-.65 G(llo)
-3.57 E 1.07(wing easy re-editing; and)-.25 F F2(IGNOREEOF)3.57 E F0(,)A
.747(whose v)72 337.2 R .747(alue indicates the number of consecuti)-.25
F 1.047 -.15(ve E)-.25 H .747(OF characters that an interacti).15 F
1.048 -.15(ve s)-.25 H .748(hell will read before).15 F -.15(ex)72 349.2
S 1.432(iting \255 an easy w).15 F 1.432(ay to k)-.1 F 1.432
(eep yourself from being logged out accidentally)-.1 F 6.432(.T)-.65 G
(he)-6.432 E F2(auto_r)3.932 E(esume)-.18 E F0 -.25(va)3.932 G(riable)
.25 E .571(alters the w)72 361.2 R .571
(ay the shell treats simple command names: if job control is acti)-.1 F
-.15(ve)-.25 G 3.071(,a).15 G .571(nd this v)-3.071 F .571
(ariable is set, sin-)-.25 F(gle-w)72 373.2 Q .239(ord simple commands \
without redirections cause the shell to \214rst look for and restart a \
suspended job)-.1 F(with that name before starting a ne)72 385.2 Q 2.5
(wp)-.25 G(rocess.)-2.5 E F2 2.5(4.6. Brace)72 409.2 R(Expansion)2.5 E
F0 .653(Since sh of)97 424.8 R .653(fers no con)-.25 F -.15(ve)-.4 G
.653(nient w).15 F .653
(ay to generate arbitrary strings that share a common pre\214x or suf)
-.1 F<8c78>-.25 E 2.124(\(\214lename e)72 436.8 R 2.124
(xpansion requires that the \214lenames e)-.15 F 2.123
(xist\), Bash implements)-.15 F F3(br)4.623 E 2.123(ace e)-.15 F
(xpansion)-.2 E F0 4.623(,ac)C(apability)-4.623 E(pick)72 448.8 Q .773
(ed up from csh.)-.1 F .774(Brace e)5.773 F .774
(xpansion is similar to \214lename e)-.15 F .774(xpansion, b)-.15 F .774
(ut the strings generated need not)-.2 F 1.211(correspond to e)72 460.8
R 1.211(xisting \214les.)-.15 F 3.711(Ab)6.211 G 1.211(race e)-3.711 F
1.211(xpression consists of an optional)-.15 F F3(pr)3.71 E(eamble)-.37
E F0 3.71(,f)C(ollo)-3.71 E 1.21(wed by a pair of)-.25 F 2.938
(braces enclosing a series of comma-separated strings, and an optional)
72 472.8 R F3(postamble)5.438 E F0 7.938(.T)C 2.938(he preamble is)
-7.938 F(prepended to each string within the braces, and the postamble \
is then appended to each resulting string:)72 484.8 Q F1 6($e)97 502.8 S
(cho a{d,c,b}e)-6 E(ade ace abe)97 514.8 Q F0 .306(As this e)72 536.4 R
.306(xample demonstrates, the results of brace e)-.15 F .305
(xpansion are not sorted, as the)-.15 F 2.805(ya)-.15 G .305
(re by \214lename e)-2.805 F(xpan-)-.15 E(sion.)72 548.4 Q F2 2.5
(4.7. Pr)72 572.4 R(ocess Substitution)-.18 E F0 .457
(On systems that can support it, Bash pro)97 588 R .457(vides a f)-.15 F
.457(acility kno)-.1 F .458(wn as)-.25 F F3(pr)2.958 E .458
(ocess substitution)-.45 F F0 5.458(.P)C .458(rocess sub-)-5.458 F .347
(stitution is similar to command substitution in that its speci\214cati\
on includes a command to e)72 600 R -.15(xe)-.15 G .346(cute, b).15 F
.346(ut the)-.2 F .181(shell does not collect the command')72 612 R
2.681(so)-.55 G .181(utput and insert it into the command line.)-2.681 F
(Rather)5.181 E 2.681(,B)-.4 G .182(ash opens a pipe)-2.681 F 1.861
(to the command, which is run in the background.)72 624 R 1.861
(The shell uses named pipes \(FIFOs\) or the)6.861 F F3(/de)4.361 E
(v/fd)-.15 E F0 .961(method of naming open \214les to e)72 636 R .962(x\
pand the process substitution to a \214lename which connects to the pip\
e)-.15 F .104(when opened.)72 648 R .103
(This \214lename becomes the result of the e)5.104 F 2.603
(xpansion. Process)-.15 F .103(substitution can be used to com-)2.603 F
(pare the outputs of tw)72 660 Q 2.5(od)-.1 G(if)-2.5 E(ferent v)-.25 E
(ersions of an application as part of a re)-.15 E(gression test:)-.15 E
F1 6($c)97 678 S(mp <\(old_prog\) <\(new_prog\))-6 E EP
%%Page: 7 7
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Roman@0 SF(-7-)282.17 48 Q/F1 10/Times-Bold@0 SF 2.5
(4.8. Pr)72 84 R(ompt Customization)-.18 E F0 2.229
(One of the more popular interacti)97 99.6 R 2.529 -.15(ve f)-.25 H
2.229(eatures that Bash pro).15 F 2.23
(vides is the ability to customize the)-.15 F 3.234(prompt. Both)72
111.6 R F1($PS1)3.234 E F0(and)3.234 E F1($PS2,)3.234 E F0 .734
(the primary and secondary prompts, are e)3.234 F .733
(xpanded before being displayed.)-.15 F -.15(Pa)72 123.6 S .804
(rameter and v).15 F .804(ariable e)-.25 F .805
(xpansion is performed when the prompt string is e)-.15 F .805
(xpanded, so an)-.15 F 3.305(ys)-.15 G .805(hell v)-3.305 F(ariable)-.25
E .729(can be put into the prompt \(e.g.,)72 135.6 R F1($SHL)3.228 E(VL)
-.92 E F0 3.228(,w)C .728(hich indicates ho)-3.228 F 3.228(wd)-.25 G
.728(eeply the current shell is nested\).)-3.228 F(Bash)5.728 E 1.895(s\
pecially interprets characters in the prompt string preceded by a backs\
lash.)72 147.6 R 1.895(Some of these backslash)6.895 F .874
(escapes are replaced with the current time, the date, the current w)72
159.6 R .874(orking directory)-.1 F 3.373(,t)-.65 G .873
(he username, and the)-3.373 F .78
(command number or history number of the command being entered.)72 171.6
R .781(There is e)5.781 F -.15(ve)-.25 G 3.281(nab).15 G .781
(ackslash escape to)-3.281 F .007
(cause the shell to change its prompt when running as root after an)72
183.6 R/F2 10/Times-Italic@0 SF(su)2.507 E F0 5.007(.B)C .007
(efore printing each primary prompt,)-5.007 F .305(Bash e)72 195.6 R
.305(xpands the v)-.15 F(ariable)-.25 E F1($PR)2.805 E(OMPT_COMMAND)-.3
E F0 .305(and, if it has a v)2.805 F .306(alue, e)-.25 F -.15(xe)-.15 G
.306(cutes the e).15 F .306(xpanded v)-.15 F .306(alue as)-.25 F 3.735
(ac)72 207.6 S 1.235(ommand, allo)-3.735 F 1.234
(wing additional prompt customization.)-.25 F -.15(Fo)6.234 G 3.734(re)
.15 G 1.234(xample, this assignment causes the current)-3.884 F(user)72
219.6 Q 2.917(,t)-.4 G .417
(he current host, the time, the last component of the current w)-2.917 F
.417(orking directory)-.1 F 2.917(,t)-.65 G .418(he le)-2.917 F -.15(ve)
-.25 G 2.918(lo).15 G 2.918(fs)-2.918 G .418(hell nest-)-2.918 F(ing, a\
nd the history number of the current command to be embedded into the pr\
imary prompt:)72 231.6 Q/F3 10/Courier@0 SF 6($P)97 249.6 S
(S1='\\u@\\h [\\t] \\W\($SHLVL:\\!\)\\$ ')-6 E
(chet@odin [21:03:44] documentation\(2:636\)$ cd ..)97 261.6 Q
(chet@odin [21:03:54] src\(2:637\)$)97 273.6 Q F0 .146(The string being\
 assigned is surrounded by single quotes so that if it is e)72 295.2 R
.146(xported, the v)-.15 F .146(alue of)-.25 F F1($SHL)2.646 E(VL)-.92 E
F0(will)2.646 E(be updated by a child shell:)72 307.2 Q F3
(chet@odin [21:17:35] src\(2:638\)$ export PS1)97 325.2 Q
(chet@odin [21:17:40] src\(2:639\)$ bash)97 337.2 Q
(chet@odin [21:17:46] src\(3:696\)$)97 349.2 Q F0
(The \\$ escape is displayed as \231)72 370.8 Q F1($)A F0 2.5<9a77>C
(hen running as a normal user)-2.5 E 2.5(,b)-.4 G(ut as \231)-2.7 E F1
(#)A F0 2.5<9a77>C(hen running as root.)-2.5 E F1 2.5(4.9. File)72 394.8
R(System V)2.5 E(iews)-.37 E F0 .029(Since Berk)97 410.4 R(ele)-.1 E
2.529(yi)-.15 G .029
(ntroduced symbolic links in 4.2 BSD, one of their most anno)-2.529 F
.03(ying properties has been)-.1 F .764(the \231w)72 422.4 R .764
(arping\232 to a completely dif)-.1 F .764
(ferent area of the \214le system when using)-.25 F F1(cd)3.263 E F0
3.263(,a)C .763(nd the resultant non-intu-)-3.263 F(iti)72 434.4 Q .704
-.15(ve b)-.25 H(eha).15 E .405(vior of \231)-.2 F F1 .405(cd ..)B F0
2.905(\232. The)B/F4 9/Times-Roman@0 SF(UNIX)2.905 E F0 -.1(ke)2.905 G
.405(rnel treats symbolic links).1 F F2(physically)2.905 E F0 5.405(.W)C
.405(hen the k)-5.405 F .405(ernel is translating)-.1 F 3.223(ap)72
446.4 S .723(athname in which one component is a symbolic link, it repl\
aces all or part of the pathname while pro-)-3.223 F .668
(cessing the link.)72 458.4 R .668
(If the contents of the symbolic link be)5.668 F .669
(gin with a slash, the k)-.15 F .669(ernel replaces the pathname)-.1 F
.219(entirely; if not, the link contents replace the current component.)
72 470.4 R .219(In either case, the symbolic link is visible.)5.219 F
.058(If the link v)72 482.4 R .058(alue is an absolute pathname, the us\
er \214nds himself in a completely dif)-.25 F .059
(ferent part of the \214le sys-)-.25 F(tem.)72 494.4 Q .704(Bash pro)97
510 R .704(vides a)-.15 F F2(lo)3.203 E(gical)-.1 E F0(vie)3.203 E 3.203
(wo)-.25 G 3.203(ft)-3.203 G .703(he \214le system.)-3.203 F .703
(In this def)5.703 F .703(ault mode, command and \214lename com-)-.1 F
.522(pletion and b)72 522 R .522(uiltin commands such as)-.2 F F1(cd)
3.022 E F0(and)3.022 E F1(pushd)3.022 E F0 .522
(which change the current w)3.022 F .522(orking directory transpar)-.1 F
(-)-.2 E .127(ently follo)72 534 R 2.627(ws)-.25 G .127
(ymbolic links as if the)-2.627 F 2.627(yw)-.15 G .127(ere directories.)
-2.627 F(The)5.126 E F1($PWD)2.626 E F0 -.25(va)2.626 G .126
(riable, which holds the shell').25 F 2.626(si)-.55 G .126(dea of)-2.626
F .366(the current w)72 546 R .366(orking directory)-.1 F 2.866(,d)-.65
G .367
(epends on the path used to reach the directory rather than its ph)
-2.866 F .367(ysical loca-)-.05 F
(tion in the local \214le system hierarch)72 558 Q 3.8 -.65(y. F)-.05 H
(or e).5 E(xample:)-.15 E F3 6($c)97 576 S 6(d/)-6 G(usr/local/bin)-6 E
6($e)97 588 S(cho $PWD)-6 E(/usr/local/bin)97 600 Q 6($p)97 612 S(wd)-6
E(/usr/local/bin)97 624 Q 6($/)97 636 S(bin/pwd)-6 E
(/net/share/sun4/local/bin)97 648 Q 6($c)97 660 S 6(d.)-6 G(.)-6 E 6($p)
97 672 S(wd)-6 E(/usr/local)97 684 Q 6($/)97 696 S(bin/pwd)-6 E
(/net/share/sun4/local)97 708 Q 6($c)97 720 S 6(d.)-6 G(.)-6 E EP
%%Page: 8 8
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Roman@0 SF(-8-)282.17 48 Q/F1 10/Courier@0 SF 6($p)97 84 S
(wd)-6 E(/usr)97 96 Q 6($/)97 108 S(bin/pwd)-6 E(/usr)97 120 Q F0 .3(On\
e problem with this, of course, arises when programs that do not unders\
tand the shell')72 141.6 R 2.8(sl)-.55 G .3(ogical notion of)-2.8 F .217
(the \214le system interpret \231..)72 153.6 R 2.718<9a64>-.7 G(if)
-2.718 E(ferently)-.25 E 5.218(.T)-.65 G .218
(his generally happens when Bash completes \214lenames containing)-5.218
F(\231..)72 165.6 Q 3.384<9a61>-.7 G .884
(ccording to a logical hierarch)-3.384 F 3.384(yw)-.05 G .884
(hich does not correspond to their ph)-3.384 F .883(ysical location.)
-.05 F -.15(Fo)5.883 G 3.383(ru).15 G .883(sers who)-3.383 F
(\214nd this troublesome, a corresponding)72 177.6 Q/F2 10
/Times-Italic@0 SF(physical)2.5 E F0(vie)2.5 E 2.5(wo)-.25 G 2.5(ft)-2.5
G(he \214le system is a)-2.5 E -.25(va)-.2 G(ilable:).25 E F1 6($c)97
195.6 S 6(d/)-6 G(usr/local/bin)-6 E 6($p)97 207.6 S(wd)-6 E
(/usr/local/bin)97 219.6 Q 6($s)97 231.6 S(et -o physical)-6 E 6($p)97
243.6 S(wd)-6 E(/net/share/sun4/local/bin)97 255.6 Q/F3 10/Times-Bold@0
SF 2.5(4.10. Inter)72 285.6 R(nationalization)-.15 E F0 .145
(One of the most signi\214cant impro)97 301.2 R -.15(ve)-.15 G .145
(ments in v).15 F .145(ersion 1.13 of Bash w)-.15 F .145
(as the change to \231eight-bit clean-)-.1 F 2.933(liness\232. Pre)72
313.2 R .433(vious v)-.25 F .432
(ersions used the eighth bit of characters to mark whether or not the)
-.15 F 2.932(yw)-.15 G .432(ere quoted when)-2.932 F 1.495(performing w)
72 325.2 R 1.495(ord e)-.1 F 3.995(xpansions. While)-.15 F 1.495
(this did not af)3.995 F 1.496
(fect the majority of users, most of whom used only)-.25 F(se)72 337.2 Q
-.15(ve)-.25 G 1.236(n-bit ASCII characters, some found it con\214ning.)
.15 F(Be)6.236 E 1.236(ginning with v)-.15 F 1.236
(ersion 1.13, Bash implemented a)-.15 F(dif)72 349.2 Q .02(ferent quoti\
ng mechanism that did not alter the eighth bit of characters.)-.25 F
.021(This allo)5.021 F .021(wed Bash to manipulate)-.25 F .427
(\214les with \231odd\232 characters in their names, b)72 361.2 R .427
(ut did nothing to help users enter those names, so v)-.2 F .426
(ersion 1.13)-.15 F 1.458
(introduced changes to readline that made it eight-bit clean as well.)72
373.2 R 1.458(Options e)6.458 F 1.458(xist that force readline to)-.15 F
.744(attach no special signi\214cance to characters with the eighth bit\
 set \(the def)72 385.2 R .744(ault beha)-.1 F .744(vior is to con)-.2 F
-.15(ve)-.4 G .744(rt these).15 F .641(characters to meta-pre\214x)72
397.2 R .641(ed k)-.15 F .941 -.15(ey s)-.1 H .642
(equences\) and to output these characters without con).15 F -.15(ve)-.4
G .642(rsion to meta-pre-).15 F<8c78>72 409.2 Q .008(ed sequences.)-.15
F .007(These changes, along with the e)5.007 F .007(xpansion of k)-.15 F
-.15(ey)-.1 G .007(maps to a full eight bits, enable readline to).15 F
-.1(wo)72 421.2 S(rk with most of the ISO-8859 f).1 E
(amily of character sets, used by man)-.1 E 2.5(yE)-.15 G
(uropean countries.)-2.5 E F3 2.5(4.11. POSIX)72 445.2 R(Mode)2.5 E F0
.584(Although Bash is intended to be POSIX.2 conformant, there are area\
s in which the def)97 460.8 R .584(ault beha)-.1 F(vior)-.2 E .463
(is not compatible with the standard.)72 472.8 R -.15(Fo)5.463 G 2.962
(ru).15 G .462(sers who wish to operate in a strict POSIX.2 en)-2.962 F
.462(vironment, Bash)-.4 F .505(implements a)72 484.8 R F2 .505
(POSIX mode)3.005 F F0 5.505(.W)C .505(hen this mode is acti)-5.505 F
-.15(ve)-.25 G 3.005(,B).15 G .505(ash modi\214es its def)-3.005 F .505
(ault operation where it dif)-.1 F(fers)-.25 E .267
(from POSIX.2 to match the standard.)72 496.8 R .266
(POSIX mode is entered when Bash is started with the)5.267 F F3(-posix)
2.766 E F0(option.)2.766 E .149(This feature is also a)72 508.8 R -.25
(va)-.2 G .149(ilable as an option to the).25 F F3(set)2.649 E F0 -.2
(bu)2.649 G(iltin,).2 E F3 .149(set -o posix)2.649 F F0 5.149(.F)C .149
(or compatibility with other GNU)-5.299 F(softw)72 520.8 Q 4.02(are tha\
t attempts to be POSIX.2 compliant, Bash also enters POSIX mode if the \
v)-.1 F(ariable)-.25 E F3($POSIXL)72 532.8 Q(Y_CORRECT)-.92 E F0 5.824
(is set when Bash is started or assigned a v)8.324 F 5.825
(alue during e)-.25 F -.15(xe)-.15 G(cution.).15 E F3($POSIX_PED)72
544.8 Q(ANTIC)-.35 E F0 .27
(is accepted as well, to be compatible with some older GNU utilities.)
2.77 F .27(When Bash is)5.27 F .506(started in POSIX mode, for e)72
556.8 R .506(xample, it sources the \214le named by the v)-.15 F .507
(alue of)-.25 F F3($ENV)3.007 E F0 .507(rather than the \231nor)3.007 F
(-)-.2 E(mal\232 startup \214les, and does not allo)72 568.8 Q 2.5(wr)
-.25 G(eserv)-2.5 E(ed w)-.15 E(ords to be aliased.)-.1 E F3 2.5(5. New)
72 592.8 R -.25(Fe)2.5 G(atur).25 E(es and Futur)-.18 E 2.5(eP)-.18 G
(lans)-2.5 E F0 1.632(There are se)97 608.4 R -.15(ve)-.25 G 1.632
(ral features introduced in the current v).15 F 1.631(ersion of Bash, v)
-.15 F 1.631(ersion 1.14, and a number)-.15 F .241
(under consideration for future releases.)72 620.4 R .242
(This section will brie\215y detail the ne)5.242 F 2.742(wf)-.25 G .242
(eatures in v)-2.742 F .242(ersion 1.14 and)-.15 F(describe se)72 632.4
Q -.15(ve)-.25 G(ral features that may appear in later v).15 E(ersions.)
-.15 E F3 2.5(5.1. New)72 656.4 R -.25(Fe)2.5 G(atur).25 E
(es in Bash-1.14)-.18 E F0 .884(The ne)97 672 R 3.384(wf)-.25 G .884
(eatures a)-3.384 F -.25(va)-.2 G .884(ilable in Bash-1.14 answer se).25
F -.15(ve)-.25 G .883(ral of the most common requests for enhance-).15 F
2.931(ments. Most)72 684 R(notably)2.931 E 2.931(,t)-.65 G .432(here is\
 a mechanism for including non-visible character sequences in prompts, \
such)-2.931 F .136
(as those which cause a terminal to print characters in dif)72 696 R
.135(ferent colors or in standout mode.)-.25 F .135(There w)5.135 F .135
(as noth-)-.1 F .558(ing pre)72 708 R -.15(ve)-.25 G .558
(nting the use of these sequences in earlier v).15 F .559(ersions, b)
-.15 F .559(ut the readline redisplay algorithm assumed)-.2 F
(each character occupied ph)72 720 Q(ysical screen space and w)-.05 E
(ould wrap lines prematurely)-.1 E(.)-.65 E EP
%%Page: 9 9
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Roman@0 SF(-9-)282.17 48 Q .13(Readline has a fe)97 84 R
2.63(wn)-.25 G .63 -.25(ew va)-2.63 H .13(riables, se).25 F -.15(ve)-.25
G .13(ral ne).15 F 2.63(wb)-.25 G .13
(indable commands, and some additional emacs mode)-2.63 F(def)72 96 Q
.918(ault k)-.1 F 1.218 -.15(ey b)-.1 H 3.418(indings. A).15 F(ne)3.418
E 3.418(wh)-.25 G .919(istory search mode has been implemented: in this\
 mode, readline searches)-3.418 F .336(the history for lines be)72 108 R
.336(ginning with the characters between the be)-.15 F .336
(ginning of the current line and the cursor)-.15 F(.)-.55 E .555(The e)
72 120 R .556(xisting readline incremental search commands no longer ma\
tch identical lines more than once.)-.15 F(File-)5.556 E 1.979
(name completion no)72 132 R 4.479(we)-.25 G 1.979(xpands v)-4.629 F
1.979(ariables in directory names.)-.25 F 1.978(The history e)6.978 F
1.978(xpansion f)-.15 F 1.978(acilities are no)-.1 F(w)-.25 E 1.449
(nearly completely csh-compatible: missing modi\214ers ha)72 144 R 1.749
-.15(ve b)-.2 H 1.449(een added and history substitution has been).15 F
-.15(ex)72 156 S(tended.).15 E(Se)97 171.6 Q -.15(ve)-.25 G .474
(ral of the features described earlier).15 F 2.973(,s)-.4 G .473(uch as)
-2.973 F/F1 10/Times-Bold@0 SF .473(set -o posix)2.973 F F0(and)2.973 E
F1($POSIX_PED)2.973 E(ANTIC)-.35 E F0 2.973(,a)C .473(re ne)-2.973 F
2.973(wi)-.25 G(n)-2.973 E -.15(ve)72 183.6 S .106(rsion 1.14.).15 F
.106(There is a ne)5.106 F 2.606(ws)-.25 G .106(hell v)-2.606 F
(ariable,)-.25 E F1(OSTYPE)2.606 E F0 2.606(,t)C 2.606(ow)-2.606 G .106
(hich Bash assigns a v)-2.606 F .106(alue that identi\214es the v)-.25 F
(er)-.15 E(-)-.2 E 1.38(sion of)72 195.6 R/F2 9/Times-Roman@0 SF(UNIX)
3.88 E F0(it')3.88 E 3.879(sr)-.55 G 1.379(unning on \(great for puttin\
g architecture-speci\214c binary directories into the)-3.879 F F1($P)
3.879 E -.95(AT)-.74 G(H).95 E F0(\).)A -1 -.8(Tw o)72 207.6 T -.25(va)
6.215 G 2.915(riables ha).25 F 3.215 -.15(ve b)-.2 H 2.915(een renamed:)
.15 F F1($HISTCONTR)5.416 E(OL)-.3 E F0(replaces)5.416 E F1
($history_contr)5.416 E(ol)-.18 E F0 5.416(,a)C(nd)-5.416 E F1
($HOSTFILE)5.416 E F0(replaces)72 219.6 Q F1
($hostname_completion_\214le)2.521 E F0 5.021(.I)C 2.521(nb)-5.021 G
.021(oth cases, the old names are accepted for backw)-2.521 F .02
(ards compatibil-)-.1 F(ity)72 231.6 Q 5.788(.T)-.65 G .788(he ksh)
-5.788 F/F3 10/Times-Italic@0 SF(select)3.288 E F0 .788
(construct, which allo)3.288 F .788
(ws the generation of simple menus, has been implemented.)-.25 F(Ne)
5.788 E(w)-.25 E 1.496(capabilities ha)72 243.6 R 1.796 -.15(ve b)-.2 H
1.496(een added to e).15 F 1.495(xisting v)-.15 F(ariables:)-.25 E F1
($auto_r)3.995 E(esume)-.18 E F0 1.495(can no)3.995 F 3.995(wt)-.25 G
(ak)-3.995 E 3.995(ev)-.1 G 1.495(alues of)-4.245 F F3 -.2(ex)3.995 G
(act).2 E F0(or)3.995 E F3(sub-)3.995 E(string)72 255.6 Q F0 4.843(,a)C
(nd)-4.843 E F1($HISTCONTR)4.843 E(OL)-.3 E F0 2.343(understands the v)
4.843 F(alue)-.25 E F3(ignor)4.844 E(eboth)-.37 E F0 4.844(,w)C 2.344
(hich combines the tw)-4.844 F 4.844(op)-.1 G(re)-4.844 E(viously)-.25 E
1.556(acceptable v)72 267.6 R 4.056(alues. The)-.25 F F1(dirs)4.056 E F0
-.2(bu)4.056 G 1.556(iltin has acquired options to print out speci\214c\
 members of the directory).2 F 3.062(stack. The)72 279.6 R F1($nolinks)
3.062 E F0 -.25(va)3.062 G .562(riable, which forces a ph).25 F .562
(ysical vie)-.05 F 3.062(wo)-.25 G 3.062(ft)-3.062 G .563
(he \214le system, has been superseded by the)-3.062 F F1<ad50>72 291.6
Q F0 .494(option to the)2.994 F F1(set)2.994 E F0 -.2(bu)2.994 G .494
(iltin \(equi).2 F -.25(va)-.25 G .494(lent to).25 F F1 .494(set -o ph)
2.994 F(ysical)-.15 E F0 .493(\); the v)B .493
(ariable is retained for backw)-.25 F .493(ards compati-)-.1 F(bility)72
303.6 Q 5.196(.T)-.65 G .196(he v)-5.196 F .196
(ersion string contained in)-.15 F F1($B)2.696 E(ASH_VERSION)-.3 E F0
(no)2.696 E 2.696(wi)-.25 G .196(ncludes an indication of the patch le)
-2.696 F -.15(ve)-.25 G 2.696(la).15 G(s)-2.696 E .85(well as the \231b)
72 315.6 R .85(uild v)-.2 F 3.35(ersion\232. Some)-.15 F .85
(little-used features ha)3.35 F 1.15 -.15(ve b)-.2 H .85(een remo).15 F
-.15(ve)-.15 G 3.35(d: the).15 F F1(by)3.35 E(e)-.1 E F0(synon)3.35 E
.85(ym for)-.15 F F1(exit)3.35 E F0(and)3.35 E(the)72 327.6 Q F1($NO_PR)
3.498 E(OMPT_V)-.3 E(ARS)-1.35 E F0 -.25(va)3.498 G .998
(riable are gone.).25 F .998(There is no)5.998 F 3.498(wa)-.25 G 3.498
(no)-3.498 G -2.19 -.18(rg a)-3.498 H .998
(nized test suite that can be run as a).18 F(re)72 339.6 Q
(gression test when b)-.15 E(uilding a ne)-.2 E 2.5(wv)-.25 G
(ersion of Bash.)-2.65 E 1.696(The documentation has been thoroughly o)
97 355.2 R -.15(ve)-.15 G 1.696(rhauled: there is a ne).15 F 4.196(wm)
-.25 G 1.695(anual page on the readline)-4.196 F .467(library and the)72
367.2 R F3(info)2.967 E F0 .467
(\214le has been updated to re\215ect the current v)2.967 F 2.968
(ersion. As)-.15 F(al)2.968 E -.1(wa)-.1 G .468(ys, as man).1 F 2.968
(yb)-.15 G .468(ugs as possi-)-3.168 F(ble ha)72 379.2 Q .3 -.15(ve b)
-.2 H(een \214x).15 E(ed, although some surely remain.)-.15 E F1 2.5
(5.2. Other)72 403.2 R -.25(Fe)2.5 G(atur).25 E(es)-.18 E F0 1.68
(There are a fe)97 418.8 R 4.18(wf)-.25 G 1.68
(eatures that I hope to include in later Bash releases.)-4.18 F 1.68
(Some are based on w)6.68 F(ork)-.1 E(already done in other shells.)72
430.8 Q .958(In addition to simple v)97 446.4 R .959(ariables, a future\
 release of Bash will include one-dimensional arrays, using)-.25 F .206
(the ksh implementation of arrays as a model.)72 458.4 R .205
(Additions to the ksh syntax, such as)5.205 F F3(varname)2.705 E F0 .205
(=\( ... \) to assign)B 2.587(al)72 470.4 S .087(ist of w)-2.587 F .088
(ords directly to an array and a mechanism to allo)-.1 F 2.588(wt)-.25 G
(he)-2.588 E F1 -.18(re)2.588 G(ad).18 E F0 -.2(bu)2.588 G .088
(iltin to read a list of v).2 F .088(alues directly)-.25 F .092
(into an array)72 482.4 R 2.592(,w)-.65 G .092(ould be desirable.)-2.692
F(Gi)5.092 E -.15(ve)-.25 G 2.592(nt).15 G .092(hose e)-2.592 F .092
(xtensions, the ksh)-.15 F F1 .092(set \255A)2.592 F F0 .091
(syntax may not be w)2.591 F .091(orth support-)-.1 F(ing \(the)72 494.4
Q F1<ad41>2.5 E F0(option assigns a list of v)2.5 E(alues to an array)
-.25 E 2.5(,b)-.65 G(ut is a rather peculiar special case\).)-2.7 E .76
(Some shells include a means of)97 510 R F3(pr)3.26 E -.1(og)-.45 G -.15
(ra).1 G(mmable).15 E F0 -.1(wo)3.26 G .76
(rd completion, where the user speci\214es on a per).1 F(-)-.2 E .163
(command basis ho)72 522 R 2.663(wt)-.25 G .163(he ar)-2.663 F .163(gum\
ents of the command are to be treated when completion is attempted: as \
\214le-)-.18 F .194(names, hostnames, e)72 534 R -.15(xe)-.15 G .194
(cutable \214les, and so on.).15 F .195
(The other aspects of the current Bash implementation could)5.195 F .482
(remain as-is; the e)72 546 R .482(xisting heuristics w)-.15 F .481
(ould still be v)-.1 F 2.981(alid. Only)-.25 F .481
(when completing the ar)2.981 F .481(guments to a simple)-.18 F
(command w)72 558 Q(ould the programmable completion be in ef)-.1 E
(fect.)-.25 E .479(It w)97 573.6 R .479(ould also be nice to gi)-.1 F
.779 -.15(ve t)-.25 H .479(he user \214ner).15 F .479
(-grained control o)-.2 F -.15(ve)-.15 G 2.98(rw).15 G .48
(hich commands are sa)-2.98 F -.15(ve)-.2 G 2.98(do).15 G .48(nto the)
-2.98 F 1.786(history list.)72 585.6 R 1.786(One proposal is for a v)
6.786 F 1.786(ariable, tentati)-.25 F -.15(ve)-.25 G 1.786(ly named).15
F F1(HISTIGNORE)4.286 E F0 4.285(,w)C 1.785(hich w)-4.285 F 1.785
(ould contain a)-.1 F .496(colon-separated list of commands.)72 597.6 R
.496(Lines be)5.496 F .496
(ginning with these commands, after the restrictions of)-.15 F F1($HIST)
2.997 E(-)-.92 E(CONTR)72 609.6 Q(OL)-.3 E F0(ha)2.65 E .45 -.15(ve b)
-.2 H .15(een applied, w).15 F .15
(ould not be placed onto the history list.)-.1 F .15
(The shell pattern-matching capa-)5.15 F(bilities could also be a)72
621.6 Q -.25(va)-.2 G(ilable when specifying the contents of).25 E F1
($HISTIGNORE)2.5 E F0(.)A .729(One thing that ne)97 637.2 R .729
(wer shells such as)-.25 F F1(wksh)3.229 E F0 .729(\(also kno)3.229 F
.729(wn as)-.25 F F1(dtksh)3.23 E F0 3.23(\)p)C(ro)-3.23 E .73
(vide is a command to dynami-)-.15 F 1.189
(cally load code implementing additional b)72 649.2 R 1.189
(uiltin commands into a running shell.)-.2 F 1.188(This ne)6.188 F 3.688
(wb)-.25 G 1.188(uiltin w)-3.888 F(ould)-.1 E(tak)72 661.2 Q 2.875(ea)
-.1 G 2.875(no)-2.875 G .375
(bject \214le or shared library implementing the \231body\232 of the b)
-2.875 F .375(uiltin \()-.2 F F3(xxx_b)A(uiltin\(\))-.2 E F0 .375
(for those f)2.875 F(amiliar)-.1 E .052
(with Bash internals\) and a structure containing the name of the ne)72
673.2 R 2.552(wc)-.25 G .051(ommand, the function to call when the)
-2.552 F(ne)72 685.2 Q 3.458(wb)-.25 G .958(uiltin is in)-3.658 F -.2
(vo)-.4 G -.1(ke).2 G 3.458(d\().1 G .959
(presumably de\214ned in the shared object speci\214ed as an ar)-3.458 F
.959(gument\), and the docu-)-.18 F 1.352
(mentation to be printed by the)72 697.2 R F1(help)3.851 E F0 1.351
(command \(possibly present in the shared object as well\).)3.851 F
1.351(It w)6.351 F(ould)-.1 E(manage the details of e)72 709.2 Q
(xtending the internal table of b)-.15 E(uiltins.)-.2 E EP
%%Page: 10 10
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Roman@0 SF(-10-)279.67 48 Q 3.291(Af)97 84 S 1.291 -.25
(ew o)-3.291 H .791(ther b).25 F .791(uiltins w)-.2 F .791
(ould also be desirable: tw)-.1 F 3.291(oa)-.1 G .791(re the POSIX.2)
-3.291 F/F1 10/Times-Bold@0 SF(getconf)3.292 E F0 .792
(command, which prints)3.292 F 1.412(the v)72 96 R 1.412
(alues of system con\214guration v)-.25 F 1.411
(ariables de\214ned by POSIX.2, and a)-.25 F F1(diso)3.911 E(wn)-.1 E F0
-.2(bu)3.911 G 1.411(iltin, which causes a).2 F 1.347
(shell running with job control acti)72 108 R 1.647 -.15(ve t)-.25 H
3.847<6f99>.15 G(for)-3.847 E 1.347
(get about\232 one or more background jobs in its internal jobs)-.18 F
3.465(table. Using)72 120 R F1(getconf)3.465 E F0 3.465(,f)C .965(or e)
-3.465 F .965(xample, a user could retrie)-.15 F 1.264 -.15(ve a v)-.25
H .964(alue for)-.1 F F1($P)3.464 E -.95(AT)-.74 G(H).95 E F0 .964
(guaranteed to \214nd all of the)3.464 F .884
(POSIX standard utilities, or \214nd out ho)72 132 R 3.385(wl)-.25 G
.885
(ong \214lenames may be in the \214le system containing a speci\214ed)
-3.385 F(directory)72 144 Q(.)-.65 E 1.521
(There are no implementation timetables for an)97 159.6 R 4.021(yo)-.15
G 4.021(ft)-4.021 G 1.52(hese features, nor are there concrete plans to)
-4.021 F(include them.)72 171.6 Q(If an)5 E(yone has comments on these \
proposals, feel free to send me electronic mail.)-.15 E F1 2.5
(6. Re\215ections)72 195.6 R(and Lessons Lear)2.5 E(ned)-.15 E F0 .433
(The lesson that has been repeated most often during Bash de)97 211.2 R
-.15(ve)-.25 G .433(lopment is that there are dark corners).15 F .181
(in the Bourne shell, and people use all of them.)72 223.2 R .18
(In the original description of the Bourne shell, quoting and)5.181 F
.073(the shell grammar are both poorly speci\214ed and incomplete; subs\
equent descriptions ha)72 235.2 R .373 -.15(ve n)-.2 H .073
(ot helped much.).15 F 1.856(The grammar presented in Bourne')72 247.2 R
4.356(sp)-.55 G 1.856(aper describing the shell distrib)-4.356 F 1.855
(uted with the Se)-.2 F -.15(ve)-.25 G 1.855(nth Edition of).15 F/F2 9
/Times-Roman@0 SF(UNIX)72 259.2 Q F0 2.5<8769>C 2.5(ss)-2.5 G 2.5(of)
-2.5 G(ar of)-2.6 E 2.5(ft)-.25 G(hat it does not allo)-2.5 E 2.5(wt)
-.25 G(he command)-2.5 E/F3 10/Courier@0 SF(who|wc)2.5 E F0 5(.I)C 2.5
(nf)-5 G(act, as T)-2.6 E(om Duf)-.8 E 2.5(fs)-.25 G(tates:)-2.5 E 1.375
(Nobody really kno)97 274.8 R 1.375(ws what the Bourne shell')-.25 F
3.875(sg)-.55 G 1.375(rammar is.)-3.875 F(Ev)6.376 E 1.376(en e)-.15 F
1.376(xamination of the source)-.15 F(code is little help.\210)97 286.8
Q .382(The POSIX.2 standard includes a)72 302.4 R/F4 10/Times-Italic@0
SF(yacc)2.882 E F0 .382
(grammar that comes close to capturing the Bourne shell')2.882 F 2.882
(sb)-.55 G(eha)-2.882 E(vior)-.2 E(,)-.4 E -.2(bu)72 314.4 S 3.246(ti).2
G 3.246(td)-3.246 G(isallo)-3.246 E .747(ws some constructs which sh ac\
cepts without complaint \255 and there are scripts out there that)-.25 F
.501(use them.)72 326.4 R .501(It took a fe)5.501 F 3.001(wv)-.25 G .501
(ersions and se)-3.151 F -.15(ve)-.25 G .501(ral b).15 F .5
(ug reports before Bash implemented sh-compatible quoting,)-.2 F .279
(and there are still some \231le)72 338.4 R -.05(ga)-.15 G .279
(l\232 sh constructs which Bash \215ags as syntax errors.).05 F .28
(Complete sh compatibility)5.28 F(is a tough nut.)72 350.4 Q 1.231
(The shell is bigger and slo)97 366 R 1.231(wer than I w)-.25 F 1.231
(ould lik)-.1 F 1.23(e, though the current v)-.1 F 1.23
(ersion is substantially f)-.15 F(aster)-.1 E .086(than pre)72 378 R
(viously)-.25 E 5.086(.T)-.65 G .087
(he readline library could stand a substantial re)-5.086 F 2.587
(write. A)-.25 F .087(hand-written parser to replace the)2.587 F
(current)72 390 Q F4(yacc)2.978 E F0 .478(-generated one w)B .477
(ould probably result in a speedup, and w)-.1 F .477(ould solv)-.1 F
2.977(eo)-.15 G .477(ne glaring problem:)-2.977 F(the)5.477 E .384
(shell could parse commands in \231$\(...\)\232 constructs as the)72 402
R 2.884(ya)-.15 G .385
(re entered, rather than reporting errors when the)-2.884 F
(construct is e)72 414 Q(xpanded.)-.15 E 1.064(As al)97 429.6 R -.1(wa)
-.1 G 1.064(ys, there is some chaf).1 F 3.564(ft)-.25 G 3.564(og)-3.564
G 3.564(ow)-3.564 G 1.064(ith the wheat.)-3.564 F 1.063
(Areas of duplicated functionality need to be)6.063 F .382(cleaned up.)
72 441.6 R .382(There are se)5.382 F -.15(ve)-.25 G .382
(ral cases where Bash treats a v).15 F .382
(ariable specially to enable functionality a)-.25 F -.25(va)-.2 G
(ilable).25 E .185(another w)72 453.6 R .185(ay \()-.1 F F1($notify)A F0
(vs.)2.684 E F1 .184(set -o notify)5.184 F F0(and)2.684 E F1($nolinks)
2.684 E F0(vs.)2.684 E F1 .184(set -o ph)2.684 F(ysical)-.15 E F0 2.684
(,f)C .184(or instance\); the special treatment)-2.684 F 3.421(of the v)
72 465.6 R 3.421(ariable name should probably be remo)-.25 F -.15(ve)
-.15 G 5.921(d. A).15 F(fe)5.921 E 5.921(wm)-.25 G 3.422
(ore things could stand remo)-5.921 F -.25(va)-.15 G 3.422(l; the).25 F
F1($allo)72 477.6 Q(w_null_glob_expansion)-.1 E F0(and)4.112 E F1
($glob_dot_\214lenames)4.112 E F0 -.25(va)4.111 G 1.611
(riables are of particularly questionable v).25 F(alue.)-.25 E(The)72
489.6 Q F1($[...])3.977 E F0 1.477(arithmetic e)3.977 F -.25(va)-.25 G
1.478(luation syntax is redundant no).25 F 3.978(wt)-.25 G 1.478
(hat the POSIX-mandated)-3.978 F F1($\(\(...\)\))3.978 E F0 1.478
(construct has)3.978 F .326(been implemented, and could be deleted.)72
501.6 R .326(It w)5.326 F .326(ould be nice if the te)-.1 F .326
(xt output by the)-.15 F F1(help)2.825 E F0 -.2(bu)2.825 G .325
(iltin were e).2 F(xter)-.15 E(-)-.2 E .061
(nal to the shell rather than compiled into it.)72 513.6 R .062
(The beha)5.062 F .062(vior enabled by)-.2 F F1
($command_oriented_history)2.562 E F0 2.562(,w)C(hich)-2.562 E 1.125
(causes the shell to attempt to sa)72 525.6 R 1.424 -.15(ve a)-.2 H
1.124(ll lines of a multi-line command in a single history entry).15 F
3.624(,s)-.65 G 1.124(hould be)-3.624 F(made the def)72 537.6 Q
(ault and the v)-.1 E(ariable remo)-.25 E -.15(ve)-.15 G(d.).15 E F1 2.5
(7. A)72 561.6 R -.1(va)-1 G(ilability).1 E F0 .047
(As with all other GNU softw)97 577.2 R .047(are, Bash is a)-.1 F -.25
(va)-.2 G .047(ilable for anon).25 F .047(ymous FTP from)-.15 F F4(pr)
2.547 E(ep.ai.mit.edu:/pub/gnu)-.37 E F0 1.05(and from other GNU softw)
72 589.2 R 1.05(are mirror sites.)-.1 F 1.049(The current v)6.049 F
1.049(ersion is in)-.15 F F4(bash-1.14.1.tar)3.549 E(.gz)-1.11 E F0
1.049(in that directory)3.549 F(.)-.65 E(Use)72 601.2 Q F4(ar)5.965 E
-.15(ch)-.37 G(ie).15 E F0 3.465(to \214nd the nearest archi)5.965 F
3.766 -.15(ve s)-.25 H 5.966(ite. The).15 F 3.466(latest v)5.966 F 3.466
(ersion is al)-.15 F -.1(wa)-.1 G 3.466(ys a).1 F -.25(va)-.2 G 3.466
(ilable for FTP from).25 F F4(bash.CWR)72 613.2 Q -.25(U.)-.4 G
(Edu:/pub/dist.).25 E F0(Bash documentation is a)5 E -.25(va)-.2 G
(ilable for FTP from).25 E F4(bash.CWR)2.5 E -.25(U.)-.4 G
(Edu:/pub/bash.).25 E F0 1.169(The Free Softw)97 628.8 R 1.169(are F)-.1
F 1.169(oundation sells tapes and CD-R)-.15 F 1.168
(OMs containing Bash; send electronic mail to)-.4 F F3
(gnu@prep.ai.mit.edu)72 640.8 Q F0(or call)2.5 E F3(+1-617-876-3296)2.5
E F0(for more information.)2.5 E .694(Bash is also distrib)97 656.4 R
.694(uted with se)-.2 F -.15(ve)-.25 G .694(ral v).15 F .694(ersions of)
-.15 F F2(UNIX)3.194 E F0 .694(-compatible systems.)B .695
(It is included as /bin/sh)5.694 F .948(and /bin/bash on se)72 668.4 R
-.15(ve)-.25 G .948(ral Linux distrib).15 F .948
(utions \(more about the dif)-.2 F .948
(ference in a moment\), and as contrib)-.25 F(uted)-.2 E .32 LW 144
676.4 72 676.4 DL/F5 8/Times-Roman@0 SF .781
(\207S. R. Bourne, \231UNIX T)72 688.2 R .781(ime-Sharing System:)-.28 F
.781(The UNIX Shell\232,)4.781 F/F6 8/Times-Italic@0 SF .78
(Bell System T)2.78 F(ec)-.736 E .78(hnical J)-.12 F(ournal)-.2 E F5
2.78(,5)C .78(7\(6\), July-)-2.78 F(August, 1978, pp. 1971-1990.)72
698.2 Q<8854>72 710 Q .431(om Duf)-.64 F .431
(f, \231Rc \255 A Shell for Plan 9 and)-.2 F/F7 7/Times-Roman@0 SF(UNIX)
2.432 E F5(systems\232,)2.432 E F6(Pr)2.432 E .432
(oc. of the Summer 1990 EUUG Confer)-.36 F(ence)-.296 E F5 2.432(,L)C
(on-)-2.432 E(don, July)72 720 Q 2(,1)-.52 G(990, pp. 21-33.)-2 E EP
%%Page: 11 11
%%BeginPageSetup
BP
%%EndPageSetup
/F0 10/Times-Roman@0 SF(-11-)279.67 48 Q(softw)72 84 Q(are in BSDI')-.1
E 2.5(sB)-.55 G(SD/386* and FreeBSD.)-2.5 E .598(The Linux distrib)97
99.6 R .598(ution deserv)-.2 F .598(es special mention.)-.15 F .598
(There are tw)5.598 F 3.099(oc)-.1 G .599
(on\214gurations included in the stan-)-3.099 F .733(dard Bash distrib)
72 111.6 R .732(ution: a \231normal\232 con\214guration, in which all o\
f the standard features are included, and a)-.2 F .519(\231minimal\232 \
con\214guration, which omits job control, aliases, history and command \
line editing, the directory)72 123.6 R .886(stack and)72 135.6 R/F1 10
/Times-Bold@0 SF(pushd/popd/dirs,)3.386 E F0 .886(process substitution,\
 prompt string special character decoding, and the)3.386 F/F2 10
/Times-Italic@0 SF(select)3.385 E F0 3.368(construct. This)72 147.6 R
.868(minimal v)3.368 F .869
(ersion is designed to be a drop-in replacement for the traditional)-.15
F/F3 9/Times-Roman@0 SF(UNIX)3.369 E F0(/bin/sh,)3.369 E
(and is included as the Linux /bin/sh in se)72 159.6 Q -.15(ve)-.25 G
(ral packagings.).15 E F1 2.5(8. Conclusion)72 183.6 R F0 .8
(Bash is a w)97 199.2 R(orth)-.1 E 3.3(ys)-.05 G .8(uccessor to sh.)-3.3
F .8(It is suf)5.8 F .8(\214ciently portable to run on nearly e)-.25 F
-.15(ve)-.25 G .8(ry v).15 F .8(ersion of)-.15 F F3(UNIX)3.299 E F0 .31
(from 4.3 BSD to SVR4.2, and se)72 211.2 R -.15(ve)-.25 G(ral).15 E F3
(UNIX)2.81 E F0 -.1(wo)2.81 G(rkalik).1 E 2.81(es. It)-.1 F .311(is rob)
2.81 F .311(ust enough to replace sh on most of those)-.2 F 1.515
(systems, and pro)72 223.2 R 1.515(vides more functionality)-.15 F 6.515
(.I)-.65 G 4.015(th)-6.515 G 1.515(as se)-4.015 F -.15(ve)-.25 G 1.515
(ral thousand re).15 F 1.515(gular users, and their feedback has)-.15 F
(helped to mak)72 235.2 Q 2.5(ei)-.1 G 2.5(ta)-2.5 G 2.5(sg)-2.5 G
(ood as it is today \255 a testament to the bene\214ts of free softw)
-2.5 E(are.)-.1 E .32 LW 144 708.2 72 708.2 DL/F4 8/Times-Roman@0 SF
(*BSD/386 is a trademark of Berk)72 720 Q(ele)-.08 E 2(yS)-.12 G(oftw)-2
E(are Design, Inc.)-.08 E EP
%%Trailer
end
%%EOF