(Ne)6.198 E 1.198(xt, features unique to bash will be)-.15 F 2.866(listed. The)72 616.8 R .366(\214rst three sections pro)2.866 F .366(vide a progressi)-.15 F-.15(ve)-.25 G .366(ly more detailed o).15 F -.15(ve)-.15 G(rvie).15 E 2.866(wo)-.25 G 2.866(fb)395.706 616.8 S 2.866(ash. Finally)406.902 616.8 R 2.866(,f)-.65 G .366(eatures of)464.484 616.8 R(ksh-88 \(the currently-a)72 628.8 Q-.25(va)-.2 G(ilable v).25 E(ersion\) not in sh or bash will be presented.)-.15E F1 2.5(4.1. Common)72 652.8 R -.25(Fe)2.5 G(atur).25 E(es)-.18 E F0 .021(All three shells ha)97 668.4 R .321 -.15(ve t)-.2 H .021(he same basic feature set, which is essentially that pro).15 F .02(vided by sh and described)-.15 F 1.026(in an)72 680.4 R 3.526(ys)-.15 G 3.526(hm)105.012 680.4 S 1.027(anual page. 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F)7284 R(eatur)-.25 E(es in bash and ksh)-.18 E F0 .458(Ksh and bash ha)97 99.6 R.758 -.15(ve s)-.2 H -2.15 -.25(ev e).15 H .459(ral features in common be).25 F.459(yond this base le)-.15 F -.15(ve)-.25 G 2.959(lo).15 G 2.959(ff)387.81499.6 S(unctionality)397.433 99.6 Q 5.459(.S)-.65 G .459(ome of this)458.08299.6 R(is due to the POSIX.2 standard.)72 111.6 Q(Other functions ha)5 E .3-.15(ve b)-.2 H(een implemented in bash using ksh as a guide.).15 E F1 2.5(4.2.1. V)72 135.6 R(ariables and V)-.92 E(ariable Expansion)-.92 E F0 .097(Bash and ksh ha)97 151.2 R .396 -.15(ve a)-.2 H .096(ugmented v).15 F .096(ariable e)-.25 F 2.596(xpansion. Arithmetic)-.15 F .096(substitution allo)2.596 F .096(ws an e)-.25 F .096(xpression to be)-.15 F -.25(eva)72 163.2 S .6(luated and the result substituted.).25 F .6(Shell v)5.6 F .6(ariables may be used as operands, and the result of an e)-.25 F(xpres-)-.15 E.41(sion may be assigned to a v)72 175.2 R 2.91(ariable. Nearly)-.25 F .41(all of the operators from the C language are a)2.91 F -.25(va)-.2 G .41(ilable, with the).25 F(same precedence rules:)72 187.2 Q/F2 10/Courier@0 SF 6($e)97 205.2 S(cho $\(\(3 + 5 * 32\)\))115 205.2 Q(163)97 217.2 Q F0 -1.11(Va)72 238.8 S 1.445(riables may be declared as)1.11 F/F3 10/Times-Italic@0 SF(inte)3.945 E -.1(ge)-.4 G(r).1 E F0 3.945(,w)1.666 G 1.446(hich causes arithmetic e)240.956 238.8 R -.25(va)-.25 G 1.446(luation to be performed on the v).25 F(alue)-.25 E(whene)72 250.8 Q -.15(ve)-.25 G 2.5(rt).15 G(he)115.75 250.8 Q 2.5(ya)-.15 G(re assigned to.)136.98250.8 Q .483(There are ne)97 266.4 R 2.983(we)-.25 G .483(xpansions to obtain the length of a v)162.179 266.4 R(ariable')-.25 E 2.982(sv)-.55 G .482(alue and to remo)352.19 266.4 R .782 -.15(ve s)-.15 H .482(ubstrings match-).15 F .063(ing speci\214ed patterns from the be)72 278.4 R.063(ginning and end of v)-.15 F .063(ariable v)-.25 F 2.563(alues. A)-.25 F(ne)2.563 E 2.563(wf)-.25 G .064(orm of command substitution,)383.249 278.4 RF1($\()72 290.4 Q F3(list)A F1(\))A F0 2.5(,i)C 2.5(sm)103.67 290.4 S(uch easier to nest than `)117.84 290.4 Q F3(list)A F0 2.5(`a)C(nd has simpli\214ed quoting rules.)235.04 290.4 Q .082(There are ne)97 306 R2.582(wv)-.25 G .082(ariables to control the shell')161.436 306 R 2.581(sb)-.55G(eha)284.333 306 Q(vior)-.2 E 2.581(,a)-.4 G .081(nd additional v)323.244 306R .081(ariables set or interpreted spe-)-.25 F 1.038(cially by the shell.)72318 R F1(RANDOM)6.038 E F0(and)3.538 E F1(SECONDS)3.538 E F0(are)3.539 E F3(dynamic)3.539 E F0 -.25(va)3.539 G 3.539(riables: their).25 F -.25(va)3.539 G1.039(lues are generated afresh).25 F 1.022(each time the)72 330 R 3.522(ya)-.15 G 1.022(re referenced.)140.176 330 R F1(RANDOM)6.022 E F0 1.021(returns a dif)3.521 F 1.021(ferent random number each time it is referenced,)-.25 F(and)72 342 Q F1(SECONDS)3.138 E F0 .638(returns the number of seconds since the shell w)3.138 F .638(as started or the v)-.1 F .639(ariable w)-.25 F .639(as assigned to,)-.1 F1.448(plus an)72 354 R 3.948(yv)-.15 G 1.448(alue assigned.)115.606 354 R F1(PWD)6.448 E F0(and)3.948 E F1(OLDPWD)3.947 E F0 1.447(are set to the current and pre)3.947 F 1.447(vious w)-.25 F 1.447(orking directories,)-.1 F(respecti)72 366 Q -.15(ve)-.25 G(ly).15 E(.)-.65 EF1(TMOUT)5.604 E F0 .604(controls ho)3.104 F 3.104(wl)-.25 G .604(ong the shell will w)226.436 366 R .604(ait at a prompt for input.)-.1 F(If)5.604 E F1(TMOUT)3.104 E F0 .605(is set to a)3.105 F -.25(va)72 378 S 1.168(lue greater than zero, the shell e).25 F 1.168(xits after w)-.15 F 1.168(aiting that man)-.1 F 3.668(ys)-.15 G 1.167(econds for input.)337.478 378 R F1(REPL)6.167 E(Y)-.92 E F0 1.167(is the def)3.667 F(ault)-.1 E -.25(va)72 390 S.991(riable for the).25 F F1 -.18(re)3.491 G(ad).18 E F0 -.2(bu)3.491 G .991(iltin; if no v).2 F .992(ariable names are supplied as ar)-.25 F .992(guments, the line read is assigned to)-.18 F F1(REPL)72 402 Q(Y)-.92 E F0(.)AF1 2.5(4.2.2. New)72 426 R(and Modi\214ed Builtins)2.5 E F0 .652(Both shells e)97 441.6 R .651(xpand the basic sh set of b)-.15 F .651(uiltin commands.)-.2 FF1(Let)5.651 E F0(pro)3.151 E .651(vides a w)-.15 F .651(ay to perform arithmetic)-.1 F 2.767(on shell v)72 453.6 R 5.268(ariables. Shell)-.25 F 2.768(programmers use)5.268 F F1(typeset)5.268 E F02.768(\(bash includes)5.268 F F1(declar)5.268 E(e)-.18 E F0 2.768(as a synon)5.268 F 2.768(ym\) to assign)-.15 F(attrib)72 465.6 Q .295(utes such as)-.2 FF3 -.2(ex)2.795 G(port).2 E F0(and)4.461 E F3 -.37(re)2.795 G(adonly).37 E F0.295(to v)4.461 F(ariables.)-.25 E F1(Getopts)5.295 E F0 .294(is used by shell scripts to parse script options)2.795 F .962(and ar)72 477.6R 3.462(guments. The)-.18 F F1(set)3.462 E F0 .962(command has a ne)3.462 F3.462(wo)-.25 G(ption)266.446 477.6 Q F1<ad6f>3.463 E F0 .963(which tak)3.463 F.963(es option names as ar)-.1 F 3.463(guments. Option)-.18 F 1.28(names are synon)72 489.6 R 1.28(yms for the other set options \(e.g.,)-.15 FF1<ad66>3.78 E F0(and)3.78 E F1 1.28(\255o noglob)3.78 F F0 3.78(\)o)C 3.78(rp)375.97 489.6 S(ro)388.08 489.6 Q 1.28(vide ne)-.15 F 3.78(wf)-.25 G 1.28(unctionality \()440.78 489.6 R F1(-o)A(notify)72 501.6 Q F0 3.348(,f)C .849(or e)106.178 501.6 R 3.349(xample\). The)-.15 F F1 -.18(re)3.349 G(ad).18 E F0-.2(bu)3.349 G .849(iltin tak).2 F .849(es a ne)-.1 F(w)-.25 E F1<ad72>3.349 EF0 .849(option to specify that a line ending in a backslash)3.349 F(should not be continued.)72 513.6 Q F1 2.5(4.2.3. T)72 537.6 R(ilde Expansion)-.18 E F0 -.35(Ti)97 553.2 S .252(lde e).35 F .251(xpansion is a feature adopted from the C shell.)-.15 F 2.751(At)5.251 G .251(ilde character at the be)331.172 553.2 R .251(ginning of a w)-.15 F .251(ord is)-.1 F -.15(ex)72 565.2 S(panded to either).15 E F1($HOME)2.5 E F0(or the home directory of another user)2.5 E 2.5(,d)-.4 G(epending on what follo)345.84 565.2 Q(ws the tilde.)-.25 E F1 2.5(4.2.4. Interacti)72 589.2 R .2 -.1(ve I)-.1 H(mpr).1 E -.1(ove)-.18 G(ments).1E F0 .789(The most noticable impro)97 604.8 R -.15(ve)-.15 G .789(ments o).15 F-.15(ve)-.15 G 3.289(rs).15 G 3.289(ha)263.385 604.8 S .789(re geared for interacti)276.114 604.8 R 1.089 -.15(ve u)-.25 H 3.29(se. Ksh).15 F .79(and bash pro)3.29 F .79(vide job)-.15 F .882(control in a v)72 616.8R .882(ery similar f)-.15 F .882(ashion, with the same options to enable and disable it \()-.1 F F1 .881(set -o monitor)B F0 3.381(\)a)C .881(nd the)478.399 616.8 R(same b)72 628.8 Q(uiltin commands to manipulate jobs \()-.2 E F1(jobs/fg/bg/kill/wait)A F0(\).)A.866(Command line editing, with emacs and vi-style k)97 644.4 R 1.166 -.15(ey b)-.1 H .866(indings, is a).15 F -.25(va)-.2 G .866(ilable in both shells.).25 F .866(The Bash)5.866 F F3 -.37(re)72 656.4 S(adline).37 E F0 1.578(library is considerably more sophisticated than the ksh editing library:)5.744F 1.577(it allo)6.577 F 1.577(ws arbitrary k)-.25 F -.15(ey)-.1 G 1.867(bindings, macros, a per)72 668.4 R 1.868(-user customization \214le \()-.2 FF3(~/.inputr)A(c)-.37 E F0 1.868(\), a number of v)B 1.868(ariables to further customize)-.25 F(beha)72 680.4 Q(vior)-.2 E 3.538(,a)-.4 G1.038(nd a much lar)116.868 680.4 R 1.038(ger set of bindable editing commands.)-.18 F 1.037(The ksh editing library pro)6.037 F 1.037(vides a small)-.15 F<8c78>72 692.4 Q(ed command set and only clumsy macros.)-.15 E .706(Both shells of)97 708 R.706(fer access to the command history)-.25 F 5.706(.T)-.65 G .706(he in-line editing options ha)307.278 708 R 1.006 -.15(ve d)-.2 H(ef).15 E.706(ault k)-.1 F 1.006 -.15(ey b)-.1 H(ind-).15 E .624(ings to access the history list.)72 720 R(The)5.624 E F1(fc)3.124 E F0 .624(command is pro)3.124 F .624(vided to re-e)-.15 F -.15(xe)-.15 G .623(cute pre).15 F .623(vious commands and display)-.25 F EP%%Page: 6 6%%BeginPageSetupBP%%EndPageSetup/F0 10/Times-Roman@0 SF 2.5(-6-)279.67 48 S(the contents of the history list.)72 84 Q/F1 10/Times-Bold@0 SF 2.5(4.2.5. 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V)-.25 F 1.234(ariables declared with)-1.11 F F1(typeset)3.734 E F0 1.234(\(or the)3.734 F .001(bash synon)72 211.2 R(ym,)-.15E F1(local)2.501 E F0 .001(\), ha)B .301 -.15(ve a s)-.2 H .001(cope restricted to the function and its descendents, and may shado).15 F 2.502(wv)-.25 G(ariables)472.9 211.2 Q(de\214ned by the in)72 223.2 Q -.2(vo)-.4 G(king shell.).2 E(Local v)5 E(ariables are remo)-.25 E -.15(ve)-.15 G 2.5(dw).15 G(hen a function completes.)317.75 223.2 Q F1 2.5(4.3. F)72 247.2 R(eatur)-.25 E(es Unique to bash)-.18 E F0(Naturally)97 262.8 Q 2.895(,b)-.65 G .395(ash includes features not in sh or ksh.)144.515 262.8 R .395(This section discusses some of the features which)5.395 F(mak)72 274.8 Q 2.986(eb)-.1 G .486(ash unique.)101.546 274.8 R .486(Most of them pro)5.486 F .486(vide impro)-.15 F -.15(ve)-.15 G 2.986(di).15 G(nteracti)288.098 274.8 Q .787-.15(ve u)-.25 H .487(se, b).15 F .487(ut a fe)-.2 F 2.987(wp)-.25 G .487(rogramming impro)394.653 274.8 R -.15(ve)-.15 G(ments).15 E(are present as well.)72 286.8 Q(Full descriptions of these features can be found in the bash documentation.)5E F1 2.5(4.3.1. 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