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//proc/self/root/usr/share/doc/bash-3.2/rose94.ps
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/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, the Bour)210.99 123 Q(ne\255Again Shell)-.18 E/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(ABSTRA)264.535 213 Q(CT)-.3 E/F2 10/Times-Roman@0 SF .019(An o)133 237 R -.15(ve)-.15 G(rvie).15 E 2.519(wo)-.25 G 2.519(f/)191.918 237 S .018 (bin/sh\255compatible shells is presented, as well as an introduction to) 200.547 237 R .128(the POSIX.2 shell and tools standard.)108 249 R .128 (These serv)5.128 F 2.628(ea)-.15 G 2.628(sa)318.562 249 S 2.628(ni)329.52 249 S 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Functions)72 513.6 R(may ha)2.5 E .3 -.15(ve t)-.2 H(heir o).15 E (wn ar)-.25 E(gument lists and local v)-.18 E(ariables, and may be recursi)-.25 E -.15(ve)-.25 G(.).15 E .722(The shell language pro)97 529.2 R .722(vides v) -.15 F .722(ariables, which may be both set and referenced.)-.25 F 3.222(An) 5.722 G .722(umber of special)435.906 529.2 R 1.02 (parameters are present, such as)72 541.2 R F1($@)3.519 E F0 3.519(,w)C 1.019 (hich returns the shell')231.257 541.2 R 3.519(sp)-.55 G 1.019 (ositional parameters \(command-line ar)333.103 541.2 R(gu-)-.18 E(ments\),)72 553.2 Q F1($?)2.906 E F0 2.906(,t)C .406(he e)122.812 553.2 R .406 (xit status of the pre)-.15 F .406(vious command, and)-.25 F F1($$)2.906 E F0 2.906(,t)C .406(he shell')322.436 553.2 R 2.906(sp)-.55 G .406(rocess I.D.) 368.248 553.2 R .407(In addition to pro)5.406 F(vid-)-.15 E .129 (ing special parameters and user)72 565.2 R .129(-de\214ned v)-.2 F .129 (ariables, the shell permits the v)-.25 F .128(alues of certain v)-.25 F .128 (ariables to control)-.25 F .16(its beha)72 577.2 R(vior)-.2 E 5.16(.S)-.55 G .16(ome of these v)131.57 577.2 R .16(ariables include)-.25 F F1(IFS)2.661 E F0 2.661(,w)C .161(hich controls ho)284.202 577.2 R 2.661(wt)-.25 G .161 (he shell splits w)361.375 577.2 R(ords,)-.1 E F1 -.74(PA)2.661 G(TH)-.21 E F0 2.661(,w)C(hich)486.78 577.2 Q .392 (tells the shell where to look for commands, and)72 589.2 R F1(PS1)2.892 E F0 2.892(,w)C .392(hose v)297.01 589.2 R .392 (alue is the string the shell uses to prompt for)-.25 F 3.371(commands. 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F).25 F 1.388(or e)-.15 F 1.388(xample, there are)-.15 F(${)72 676.8 Q F2(name)A F0<3aad>A F2(wor)A(d)-.37 E F0 .891(}, which e)B .891 (xpands to)-.15 F F2(wor)3.391 E(d)-.37 E F0(if)3.391 E F2(name)3.391 E F0 .891 (is unset or null, and the in)3.391 F -.15(ve)-.4 G .89(rse ${).15 F F2(name)A F0(:+)A F2(wor)A(d)-.37 E F0 .89(}, which)B -.15(ex)72 688.8 S 1.203(pands to) .15 F F2(wor)3.703 E(d)-.37 E F0(if)3.703 E F2(name)3.703 E F0 1.203 (is set and not null.)3.703 F F2 1.203(Command substitution)6.203 F F0(allo) 3.703 E 1.204(ws the output of a command to)-.25 F .918 (replace the command name.)72 700.8 R .918(The syntax is `)5.918 F F2(command)A F0(`.)A F2(Command)5.918 E F0 .918(is e)3.418 F -.15(xe)-.15 G .918 (cuted and it and the backquotes).15 F .299 (are replaced by its output, with trailing ne)72 712.8 R .299(wlines remo)-.25 F -.15(ve)-.15 G(d.).15 E F2 -.8(Pa)5.299 G .299(thname e).8 F(xpansion)-.2 E F0 .299(is a w)2.799 F .299(ay to e)-.1 F .299(xpand a w)-.15 F(ord)-.1 E 1.586 (to a set of \214lenames.)72 724.8 R -.8(Wo)6.586 G 1.586(rds are re).8 F -.05 (ga)-.15 G 1.586(rded as patterns, in which the characters).05 F F1(*)4.086 E F0(,)A F1(?)4.086 E F0 4.085(,a)C(nd)432.115 724.8 Q F1([)4.085 E F0(ha)4.085 E 1.885 -.15(ve s)-.2 H(pecial).15 E EP %%Page: 3 3 %%BeginPageSetup BP %%EndPageSetup /F0 10/Times-Roman@0 SF 2.5(-3-)279.67 48 S 2.845(meaning. W)72 84 R .346(ords\ containing these special characters are replaced with a sorted list of matchi\ ng pathnames.)-.8 F(If a w)72 96 Q (ord generates no matches, it is left unchanged.)-.1 E/F1 10/Times-Italic@0 SF (Quoting)97 111.6 Q F0 .85(is used to remo)3.35 F 1.15 -.15(ve t)-.15 H .85 (he special meaning of characters or w).15 F 3.35(ords. It)-.1 F .85 (can disable special treat-)3.35 F .314 (ment for shell operators or other special characters, pre)72 123.6 R -.15(ve) -.25 G .315(nt reserv).15 F .315(ed w)-.15 F .315 (ords from being recognized as such,)-.1 F .683(and inhibit v)72 135.6 R .683 (ariable e)-.25 F 3.183(xpansion. The)-.15 F .683 (shell has three quoting mechanisms:)3.183 F 3.183(ab)5.683 G .683 (ackslash preserv)387.413 135.6 R .682(es the literal)-.15 F -.25(va)72 147.6 S .417(lue of the ne).25 F .417(xt character)-.15 F 2.917(,ap)-.4 G .417 (air of single quotes preserv)196.712 147.6 R .417(es the literal v)-.15 F .418 (alue of each character between the)-.25 F 1.426 (quotes, and a pair of double quotes preserv)72 159.6 R 1.425 (es the literal meaning of enclosed characters while allo)-.15 F(wing)-.25 E (some e)72 171.6 Q(xpansions.)-.15 E 1.054(Some of the commands b)97 187.2 R 1.054(uilt into the shell are part of the programming language.)-.2 F(The)6.055 E/F2 10/Times-Bold@0 SF(br)3.555 E(eak)-.18 E F0(and)3.555 E F2(continue)72 199.2 Q F0 1.175(commands control loop e)3.675 F -.15(xe)-.15 G 1.175 (cution as in the C language.).15 F(The)6.175 E F2 -2.3 -.15(ev a)3.675 H(l).15 E F0 -.2(bu)3.675 G 1.174(iltin allo).2 F 1.174(ws a string to be)-.25 F .204 (parsed and e)72 211.2 R -.15(xe)-.15 G .204(cuted as a command.).15 F F2 -.65 (Wa)5.205 G(it).65 E F0 .205 (tells the shell to pause until the processes speci\214ed as ar)2.705 F (guments)-.18 E(ha)72 223.2 Q .3 -.15(ve ex)-.2 H(ited.).15 E F2 2.5 (2.3. Interacti)72 247.2 R .2 -.1(ve F)-.1 H(eatur)-.15 E(es)-.18 E F0 .51 (Shells ha)97 262.8 R .81 -.15(ve b)-.2 H -.15(eg).15 G .51(un of).15 F .51 (fering features geared speci\214cally for interacti)-.25 F .81 -.15(ve u)-.25 H .51(se rather than to augment the).15 F .76(programming language.)72 274.8 R .761(These interacti)5.76 F 1.061 -.15(ve f)-.25 H .761 (eatures include job control, command line editing, history and).15 F(aliases.) 72 286.8 Q .626(Job control is a f)97 302.4 R .626(acility pro)-.1 F .626 (vided jointly by the shell and the)-.15 F/F3 9/Times-Roman@0 SF(UNIX)3.125 E F0 -.1(ke)3.125 G .625(rnel that allo).1 F .625(ws users to selec-)-.25 F(ti)72 314.4 Q -.15(ve)-.25 G .344 (ly stop \(suspend\) and restart \(resume\) processes.).15 F .345 (Each pipeline e)5.345 F -.15(xe)-.15 G .345 (cuted by the shell is referred to as a).15 F F1(job)72 326.4 Q F0 2.989(.J)C .488(obs may be suspended and restarted in either the fore)94.159 326.4 R .488 (ground, where the)-.15 F 2.988(yh)-.15 G -2.25 -.2(av e)397.148 326.4 T .488 (access to the terminal,)3.188 F .833(or background, where the)72 338.4 R 3.333 (ya)-.15 G .834(re isolated and cannot read from the terminal.)189.312 338.4 R -.8(Ty)5.834 G .834(ping the).8 F F1(suspend)3.334 E F0(character)5 E .459(whi\ le a process is running stops that process and returns control to the shell.)72 350.4 R .459(Once a job is suspended, the)5.459 F .392 (user manipulates the job')72 362.4 R 2.892(ss)-.55 G .392(tate, using)184.118 362.4 R F2(bg)2.892 E F0 .393(to continue it in the background,)2.892 F F2(fg) 2.893 E F0 .393(to return it to the fore)2.893 F(ground)-.15 E .891(and a)72 374.4 R -.1(wa)-.15 G .891(it its completion, or).1 F F2(kill)3.391 E F0 .891 (to send it a signal.)3.391 F(The)5.89 E F2(jobs)3.39 E F0 .89 (command lists the status of jobs, and)3.39 F F2(wait)3.39 E F0 .407 (will pause the shell until a speci\214ed job terminates.)72 386.4 R .407 (The shell pro)5.407 F .407(vides a number of w)-.15 F .407 (ays to refer to a job,)-.1 F(and will notify the user whene)72 398.4 Q -.15 (ve)-.25 G 2.5(rab).15 G(ackground job terminates.)220.18 398.4 Q -.4(Wi)97 414 S .956(th the adv).4 F .956(ent of more po)-.15 F .956 (werful terminals and terminal emulators, more sophisticated interaction)-.25 F .253(than that pro)72 426 R .253(vided by the)-.15 F F3(UNIX)2.753 E F0 -.1(ke) 2.754 G .254(rnel terminal dri).1 F -.15(ve)-.25 G 2.754(ri).15 G 2.754(sp) 293.592 426 S 2.754(ossible. Some)305.236 426 R .254(shells of)2.754 F .254 (fer command line editing,)-.25 F 1.141 (which permits a user to edit lines of input using f)72 438 R(amiliar)-.1 E F1 (emacs)3.64 E F0(or)3.64 E F1(vi)3.64 E F0 1.14 (-style commands before submitting)B .02(them to the shell.)72 450 R .02 (Editors allo)5.02 F 2.52(wc)-.25 G .02(orrections to be made without ha)206.31 450 R .021(ving to erase back to the point of error)-.2 F 2.521(,o)-.4 G(r) 500.67 450 Q .135(start the line ane)72 462 R 3.935 -.65(w. C)-.25 H .135 (ommand line editors run the g).65 F .135(amut from a small \214x)-.05 F .134 (ed set of commands and k)-.15 F .434 -.15(ey b)-.1 H(ind-).15 E (ings to input f)72 474 Q(acilities which allo)-.1 E 2.5(wa)-.25 G (rbitrary actions to be bound to a k)217.2 474 Q .3 -.15(ey o)-.1 H 2.5(rk).15 G .3 -.15(ey s)379.88 474 T(equence.).15 E .145(Modern shells also k)97 489.6 R .145(eep a history)-.1 F 2.645(,w)-.65 G .146 (hich is the list of commands a user has typed.)243.49 489.6 R .146(Shell f) 5.146 F .146(acilities are)-.1 F -.2(av)72 501.6 S .368(ailable to recall pre) -.05 F .367(vious commands and use portions of old commands when composing ne) -.25 F 2.867(wo)-.25 G 2.867(nes. The)467.253 501.6 R 1.456 (command history can be sa)72 513.6 R -.15(ve)-.2 G 3.957(dt).15 G 3.957 (oa\214)207.522 513.6 S 1.457 (le and read back in at shell startup, so it persists across sessions.)230.436 513.6 R .675(Shells which pro)72 525.6 R .675 (vide both command editing and history generally ha)-.15 F .974 -.15(ve e)-.2 H .674(diting commands to interacti).15 F -.15(ve)-.25 G(ly).15 E(step forw)72 537.6 Q(ard and backw)-.1 E(ard through the history list.)-.1 E .013 (Aliases allo)97 553.2 R -5.012 2.513(wa s)-.25 H .014 (tring to be substituted for a command name.)164.28 553.2 R(The)5.014 E 2.514 (yc)-.15 G .014(an be used to create a mnemonic)373.396 553.2 R .568(for a)72 565.2 R F3(UNIX)3.068 E F0 .568(command name \()3.068 F/F4 10/Courier@0 SF .568 (alias del=rm)B F0 .568(\), to e)B .567(xpand a single w)-.15 F .567 (ord to a comple)-.1 F 3.067(xc)-.15 G .567(ommand \()432.603 565.2 R F4(alias) A .255(news='xterm -g 80x45 -title trn -e trn -e -S1 -N &')72 577.2 R F0 .255 (\), or to ensure that a command)B(is in)72 589.2 Q -.2(vo)-.4 G -.1(ke).2 G 2.5(dw).1 G(ith a basic set of options \()122.41 589.2 Q F4 (alias ls="/bin/ls -F")A F0(\).)A F2 2.5(3. The)72 613.2 R (POSIX Shell Standard)2.5 E F1(POSIX)97 628.8 Q F0 .239 (is a name originally coined by Richard Stallman for a f)4.405 F .239 (amily of open system standards based)-.1 F(on)72 640.8 Q F3(UNIX)3.239 E F0 5.739(.T)C .74(here are a number of aspects of)122.079 640.8 R F3(UNIX)3.24 E F0 .74(under consideration for standardization, from the basic)3.24 F .192 (system services at the system call and C library le)72 652.8 R -.15(ve)-.25 G 2.692(lt).15 G 2.692(oa)290.16 652.8 S .191 (pplications and tools to system administration and)302.292 652.8 R 2.5 (management. Each)72 664.8 R(area of standardization is assigned to a w)2.5 E (orking group in the 1003 series.)-.1 E 3.602(The POSIX Shell and T)97 680.4 R 3.602(ools standard has been de)-.8 F -.15(ve)-.25 G 3.603(loped by IEEE W).15 F 3.603(orking Group 1003.2)-.8 F -1.667(\(POSIX.2\) [4].)72 692.4 R 2.799 (It concentrates on the command interpreter interf)7.799 F 2.799 (ace and utility programs commonly)-.1 F -.15(exe)72 704.4 S 2.345 (cuted from the command line or by other programs.).15 F 2.345(An initial v) 7.345 F 2.345(ersion of the standard has been)-.15 F(appro)72 716.4 Q -.15(ve) -.15 G 2.915(da).15 G .414(nd published by the IEEE, and w)116.265 716.4 R .414 (ork is currently underw)-.1 F .414(ay to update it.)-.1 F .414 (There are four primary)5.414 F(areas of w)72 728.4 Q (ork in the 1003.2 standard:)-.1 E EP %%Page: 4 4 %%BeginPageSetup BP %%EndPageSetup /F0 10/Times-Roman@0 SF 2.5(-4-)279.67 48 S 21.5<8341>72 84 S .835 (spects of the shell')104.22 84 R 3.335(ss)-.55 G .835 (yntax and command language.)192 84 R 3.335(An)5.835 G .835(umber of special b) 338.095 84 R .835(uiltins such as)-.2 F/F1 10/Times-Bold@0 SF(cd)3.335 E F0 (and)3.335 E F1(exec)97 96 Q F0 .545(are being speci\214ed as part of the shel\ l, since their functionality usually cannot be implemented)3.046 F (by a separate e)97 108 Q -.15(xe)-.15 G(cutable;).15 E 21.5<8341>72 123.6 S .73(set of utilities to be called by shell scripts and applications.)107.45 123.6 R .731(Examples are programs lik)5.731 F(e)-.1 E/F2 10/Times-Italic@0 SF 2.397(sed, tr)3.231 F(,)-1.11 E F0(and)97 135.6 Q F2(awk.)2.853 E F0 .352 (Utilities commonly implemented as shell b)4.519 F .352 (uiltins are described in this section, such as)-.2 F F1(test)2.852 E F0(and)97 147.6 Q F1(kill)3.422 E F0 5.922(.A)C 3.422(ne)144.404 147.6 S .922 (xpansion of this section')157.116 147.6 R 3.423(ss)-.55 G .923 (cope, termed the User Portability Extension, or UPE, has)268.586 147.6 R (standardized interacti)97 159.6 Q .3 -.15(ve p)-.25 H(rograms such as).15 E F2 (vi)2.5 E F0(and)4.166 E F2(mailx;)2.5 E F0 21.5<8341>72 175.2 S .926 (group of functional interf)107.646 175.2 R .926(aces to services pro)-.1 F .926(vided by the shell, such as the traditional)-.15 F F2(system)3.425 E F0(C) 5.091 E .507(library function.)97 187.2 R .507 (There are functions to perform shell w)5.507 F .508(ord e)-.1 F .508 (xpansions, perform \214lename e)-.15 F(xpansion)-.15 E(\()97 199.2 Q F2 (globbing)A F0 .58(\), obtain v)B .58 (alues of POSIX.2 system con\214guration v)-.25 F .58(ariables, retrie)-.25 F .88 -.15(ve v)-.25 H .58(alues of en)-.1 F(vironment)-.4 E -.25(va)97 211.2 S (riables \().25 E F2 -.1(ge)C(ten).1 E(v\(\))-.4 E F0(\), and other services;) .833 E 21.5<8341>72 226.8 S(suite of `)106.72 226.8 Q(`de)-.74 E -.15(ve)-.25 G (lopment').15 E 2.5('u)-.74 G(tilities such as)209.54 226.8 Q F2(c89)2.5 E F0 (\(the POSIX.2 v)4.166 E(ersion of)-.15 E F2(cc)2.5 E F0(\), and)A F2(yacc.)2.5 E F0 .483(Bash is concerned with the aspects of the shell')97 242.4 R 2.983(sb) -.55 G(eha)301.597 242.4 Q .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)72 254.4 R 3.938(wc)-.25 G 1.438(ontrol and program e)359.688 254.4 R -.15(xe)-.15 G 1.438 (cution con-).15 F 1.145(structs, I/O redirection and pipelining, ar)72 266.4 R 1.145(gument handling, v)-.18 F 1.145(ariable e)-.25 F 1.146 (xpansion, and quoting.)-.15 F(The)6.146 E F2(special)3.646 E F0 -.2(bu)72 278.4 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) 457.504 278.4 R .7(as being part of the shell; e)72 290.4 R .7 (xamples of these are)-.15 F F1 -2.3 -.15(ev a)3.201 H(l).15 E F0(and)3.201 E F1(export)3.201 E F0 5.701(.O)C .701(ther utilities appear in the sections of) 352.034 290.4 R .256(POSIX.2 not de)72 302.4 R -.2(vo)-.25 G .256(ted to the s\ hell which are commonly \(and in some cases must be\) implemented as b).2 F (uiltin)-.2 E(commands, such as)72 314.4 Q F1 -.18(re)2.5 G(ad).18 E F0(and)2.5 E F1(test)2.5 E F0(.)A .972(POSIX.2 also speci\214es aspects of the shell')97 330 R 3.473(si)-.55 G(nteracti)286.016 330 Q 1.273 -.15(ve b)-.25 H(eha).15 E .973(vior as part of the UPE, including job)-.2 F .233 (control, command line editing, and history)72 342 R 5.233(.I)-.65 G .233 (nterestingly enough, only)253.849 342 R F2(vi)2.733 E F0 .233 (-style line editing commands ha)B -.15(ve)-.2 G(been standardized;)72 354 Q F2 (emacs)2.5 E F0(editing commands were left out due to objections.)2.5 E .148 (There were certain areas in which POSIX.2 felt standardization w)97 369.6 R .149(as necessary)-.1 F 2.649(,b)-.65 G .149(ut no e)420.643 369.6 R .149 (xisting imple-)-.15 F 1.598(mentation pro)72 381.6 R 1.598 (vided the proper beha)-.15 F(vior)-.2 E 6.598(.T)-.55 G 1.598(he w)251.56 381.6 R 1.597(orking group in)-.1 F -.15(ve)-.4 G 1.597 (nted and standardized functionality in).15 F .228(these areas.)72 393.6 R(The) 5.228 E F1(command)2.728 E F0 -.2(bu)2.728 G .228(iltin w).2 F .228(as in)-.1 F -.15(ve)-.4 G .228(nted so that shell functions could be written to replace b) .15 F(uiltins;)-.2 E 1.663(it mak)72 405.6 R 1.663 (es the capabilities of the b)-.1 F 1.663(uiltin a)-.2 F -.25(va)-.2 G 1.663 (ilable to the function.).25 F 1.663(The reserv)6.663 F 1.663(ed w)-.15 F 1.663 (ord `)-.1 F(`!')-.74 E 4.163('w)-.74 G 1.663(as added to)455.685 405.6 R(ne)72 417.6 Q -.05(ga)-.15 G .915(te the return v).05 F .915 (alue of a command or pipeline; it w)-.25 F .916(as nearly impossible to e)-.1 F .916(xpress `)-.15 F .916(`if not x')-.74 F 3.416('c)-.74 G(leanly)479.56 417.6 Q .904(using the sh language.)72 429.6 R .904(There e)5.904 F .904 (xist multiple incompatible implementations of the)-.15 F F1(test)3.403 E F0 -.2(bu)3.403 G .903(iltin, which tests).2 F .28 (\214les for type and other attrib)72 441.6 R .281 (utes and performs arithmetic and string comparisons.)-.2 F .281 (POSIX considered none)5.281 F .868(of these correct, so the standard beha)72 453.6 R .868(vior w)-.2 F .868(as speci\214ed in terms of the number of ar)-.1 F .867(guments to the com-)-.18 F 3.803(mand. POSIX.2)72 465.6 R 1.303 (dictates e)3.803 F 1.303(xactly what will happen when four or fe)-.15 F 1.303 (wer ar)-.25 F 1.303(guments are gi)-.18 F -.15(ve)-.25 G 3.803(nt).15 G(o) 459.462 465.6 Q F1(test)3.804 E F0 3.804(,a)C(nd)494 465.6 Q(lea)72 477.6 Q -.15(ve)-.2 G 4.531(st).15 G 2.031(he beha)103.951 477.6 R 2.031 (vior unde\214ned when more ar)-.2 F 2.031(guments are supplied.)-.18 F 2.03 (Bash uses the POSIX.2 algorithm,)7.031 F(which w)72 489.6 Q(as concei)-.1 E -.15(ve)-.25 G 2.5(db).15 G 2.5(yD)164.53 489.6 S -.2(av)179.25 489.6 S(id K).2 E(orn.)-.35 E 1.128 (While POSIX.2 includes much of what the shell has traditionally pro)97 505.2 R 1.129(vided, some important things)-.15 F(ha)72 517.2 Q .58 -.15(ve b)-.2 H .28 (een omitted as being `).15 F(`be)-.74 E .28(yond its scope.)-.15 F 4.26 -.74 ('' T)-.7 H .28(here is, for instance, no mention of a dif).74 F .28 (ference between)-.25 F(a)72 529.2 Q F2(lo)3.354 E(gin)-.1 E F0 .854 (shell and an)5.02 F 3.354(yo)-.15 G .854(ther interacti)167.956 529.2 R 1.154 -.15(ve s)-.25 H .854(hell \(since POSIX.2 does not specify a login program\).) .15 F .855(No \214x)5.855 F(ed)-.15 E (startup \214les are de\214ned, either \255 the standard does not mention)72 541.2 Q F2(.pr)2.5 E(o\214le)-.45 E F0(.)1.666 E F1 2.5(4. Shell)72 565.2 R (Comparison)2.5 E F0 .693(This section compares features of bash, sh, and ksh \ \(the three shells closest to POSIX compliance\).)97 580.8 R .245(Since ksh an\ d bash are supersets of sh, the features common to all three are co)72 592.8 R -.15(ve)-.15 G .245(red \214rst.).15 F .245(Some of the fea-)5.245 F 1.198 (tures bash and ksh contain which are not in sh will be discussed.)72 604.8 R (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.)-.15 E 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. Bash and ksh are both sh supersets, and so all three pro)121.318 680.4 R 1.027(vide the command inter)-.15 F(-)-.2 E .714 (preter and programming language described earlier)72 692.4 R 3.214(.T)-.55 G .714(he shell grammar)291.506 692.4 R 3.214(,s)-.4 G .714(yntax, \215o)371.568 692.4 R 3.214(wc)-.25 G .714(ontrol, redirections,)424.686 692.4 R(and b)72 704.4 Q(uiltins implemented by the Bourne shell are the baseline for subsequen\ t discussion.)-.2 E EP %%Page: 5 5 %%BeginPageSetup BP %%EndPageSetup /F0 10/Times-Roman@0 SF 2.5(-5-)279.67 48 S/F1 10/Times-Bold@0 SF 2.5(4.2. F)72 84 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)387.814 99.6 S(unctionality)397.433 99.6 Q 5.459(.S)-.65 G .459(ome of this)458.082 99.6 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.)136.98 250.8 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 R F1($\()72 290.4 Q F3(list)A F1(\))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 R 2.582(wv)-.25 G .082(ariables to control the shell')161.436 306 R 2.581(sb)-.55 G(eha)284.333 306 Q(vior)-.2 E 2.581(,a)-.4 G .081(nd additional v)323.244 306 R .081(ariables set or interpreted spe-)-.25 F 1.038(cially by the shell.)72 318 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 G 1.039(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 F 1.448(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 E F1(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(.)A F1 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 F F1(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 F0 2.768(\(bash includes)5.268 F F1(declar)5.268 E(e)-.18 E F0 2.768(as a synon) 5.268 F 2.768(ym\) to assign)-.15 F(attrib)72 465.6 Q .295(utes such as)-.2 F F3 -.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)72 477.6 R 3.462(guments. The)-.18 F F1(set)3.462 E F0 .962(command has a ne)3.462 F 3.462(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 \(e.g.,)-.15 F F1<ad66>3.78 E F0(and)3.78 E F1 1.28(\255o noglob)3.78 F F0 3.78(\)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 E F0 .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).1 E 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)72 616.8 R .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:)5.744 F 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 \()-.2 F F3(~/.inputr)A(c)-.37 E F0 1.868(\), 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 G 1.038(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 %%BeginPageSetup BP %%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(\(or the)3.734 F .001(bash synon)72 211.2 R(ym,)-.15 E F1(local)2.501 E F0 .001(\), 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.)5 E F1 2.5(4.3.1. 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All)399.37 370.8 R .53(of these v)3.03 F (ariables)-.25 E(can be set in the inputrc \214le.)72 382.8 Q .284 (The startup \214le understands a set of C preprocessor)97 398.4 R(-lik)-.2 E 2.785(ec)-.1 G .285(onditional constructs which allo)329.49 398.4 R 2.785(wv) -.25 G(ariables)472.9 398.4 Q .12(or k)72 410.4 R .42 -.15(ey b)-.1 H .119(ind\ ings to be assigned based on the application using readline, the terminal curr\ ently being used, or).15 F .316(the editing mode.)72 422.4 R .317 (Users can add program-speci\214c bindings to mak)5.317 F 2.817(et)-.1 G .317 (heir li)352.808 422.4 R -.15(ve)-.25 G 2.817(se).15 G 2.817(asier: here) 396.922 422.4 R .317(are bindings to)2.817 F(edit the v)72 434.4 Q(alue of)-.25 E F1 -.74(PA)2.5 G(TH)-.21 E F0(and double-quote the current or pre)2.5 E (vious w)-.25 E(ord:)-.1 E/F3 10/Courier@0 SF 6(#M)97 452.4 S (acros that are convenient for shell interaction)115 452.4 Q($if Bash)97 464.4 Q 6(#e)97 476.4 S(dit the path)115 476.4 Q ("\\C-xp": "PATH=${PATH}\\e\\C-e\\C-a\\ef\\C-f")97 488.4 Q 6(#p)97 500.4 S (repare to type a quoted word -- insert open and close double quotes)115 500.4 Q 6(#a)97 512.4 S(nd move to just after the open quote)115 512.4 Q ("\\C-x\\"": "\\"\\"\\C-b")97 524.4 Q 6(#Q)97 536.4 S (uote the current or previous word)115 536.4 Q("\\C-xq": "\\eb\\"\\ef\\"")97 548.4 Q($endif)97 560.4 Q F0 .322(There is a readline command to re-read the \ \214le, so users can edit the \214le, change some bindings, and be)72 582 R (gin)-.15 E(to use them almost immediately)72 594 Q(.)-.65 E .851 (Bash implements the)97 609.6 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)72 621.6 Q F0 .167(is used in se)2.667 F -.15(ve)-.25 G .167(ral w) .15 F 2.667(ays. 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History)72 192 R F0 .255 (Access to the list of commands pre)97 207.6 R .255(viously entered \(the)-.25 F/F2 10/Times-Italic@0 SF .255(command history)2.755 F F0 2.756(\)i)C 2.756(sp) 399.236 207.6 S(ro)410.882 207.6 Q .256(vided jointly by bash)-.15 F .095 (and the readline library)72 219.6 R 5.094(.B)-.65 G .094(ash pro)178.928 219.6 R .094(vides v)-.15 F .094(ariables \()-.25 F F1(HISTFILE)A F0(,)A F1(HISTSIZE) 2.594 E F0 2.594(,a)C(nd)382.068 219.6 Q F1(HISTCONTR)2.594 E(OL)-.3 E F0 2.594 (\)a)C .094(nd the)479.186 219.6 R F1(history)72 231.6 Q F0(and)2.825 E F1(fc) 2.825 E F0 -.2(bu)2.825 G .325(iltins to manipulate the history list.).2 F .325 (The v)5.325 F .325(alue of)-.25 F F1(HISTFILE)2.825 E F0 .326 (specifes the \214le where bash)2.826 F .128(writes the command history on e)72 243.6 R .128(xit and reads it on startup.)-.15 F F1(HISTSIZE)5.128 E F0 .128 (is used to limit the number of com-)2.628 F .346(mands sa)72 255.6 R -.15(ve) -.2 G 2.846(di).15 G 2.846(nt)129.002 255.6 S .346(he history)139.628 255.6 R (.)-.65 E F1(HISTCONTR)5.346 E(OL)-.3 E F0(pro)2.846 E .346 (vides a crude form of control o)-.15 F -.15(ve)-.15 G 2.846(rw).15 G .346 (hich commands are)425.548 255.6 R(sa)72 267.6 Q -.15(ve)-.2 G 2.905(do).15 G 2.905(nt)102.325 267.6 S .405(he history list: a v)113.01 267.6 R .405(alue of) -.25 F F2(ignor)2.905 E(espace)-.37 E F0 .405(means to not sa)4.571 F .705 -.15 (ve c)-.2 H .405(ommands which be).15 F .405(gin with a space; a)-.15 F -.25 (va)72 279.6 S .339(lue of).25 F F2(ignor)2.839 E(edups)-.37 E F0 .339 (means to not sa)4.505 F .64 -.15(ve c)-.2 H .34 (ommands identical to the last command sa).15 F -.15(ve)-.2 G(d.).15 E F1 (HISTCONTR)5.34 E(OL)-.3 E F0 -.1(wa)72 291.6 S 3.15(sn).1 G(amed)95.6 291.6 Q F1(history_contr)3.15 E(ol)-.18 E F0 .65(in earlier v)3.15 F .649 (ersions of bash; the old name is still accepted for backw)-.15 F .649 (ards com-)-.1 F(patibility)72 303.6 Q 5.723(.T)-.65 G(he)121.803 303.6 Q F1 (history)3.223 E F0 .724(command can read or write \214les containing the hist\ ory list and display the current)3.223 F .895(list contents.)72 315.6 R(The) 5.895 E F1(fc)3.395 E F0 -.2(bu)3.395 G .895 (iltin, adopted from POSIX.2 and the K).2 F .894(orn Shell, allo)-.35 F .894 (ws display and re-e)-.25 F -.15(xe)-.15 G(cution,).15 E .461 (with optional editing, of commands from the history list.)72 327.6 R .462 (The readline library of)5.462 F .462(fers a set of commands to)-.25 F .657(se\ arch the history list for a portion of the current input line or a string type\ d by the user)72 339.6 R 5.657(.F)-.55 G(inally)445.836 339.6 Q 3.157(,t)-.65 G (he)476.403 339.6 Q F2(his-)3.157 E(tory)72 351.6 Q F0(library)4.196 E 2.53(,g) -.65 G .03(enerally incorporated directly into the readline library)128.346 351.6 R 2.53(,i)-.65 G .03(mplements a f)350.636 351.6 R .031 (acility for history recall,)-.1 F -.15(ex)72 363.6 S .594(pansion, and re-e) .15 F -.15(xe)-.15 G .594(cution of pre).15 F .594(vious commands v)-.25 F .594 (ery similar to csh \(`)-.15 F .593(`bang history')-.74 F .593 (', so called because)-.74 F(the e)72 375.6 Q (xclamation point introduces a history substitution\):)-.15 E/F3 10/Courier@0 SF 6($e)97 393.6 S(cho a b c d e)115 393.6 Q 6(abcde)97 405.6 S 6($!)97 417.6 S 6(!fghi)115 417.6 S(echo a b c d e f g h i)97 429.6 Q 6(abcdefghi)97 441.6 S 6 ($!)97 453.6 S(-2)115 453.6 Q(echo a b c d e)97 465.6 Q 6(abcde)97 477.6 S 6 ($e)97 489.6 S(cho !-2:1-4)115 489.6 Q(echo a b c d)97 501.6 Q 6(abcd)97 513.6 S F0 1.456(The command history is only sa)72 535.2 R -.15(ve)-.2 G 3.957(dw).15 G 1.457(hen the shell is interacti)232.599 535.2 R -.15(ve)-.25 G 3.957(,s).15 G 3.957(oi)352.804 535.2 S 3.957(ti)364.541 535.2 S 3.957(sn)374.058 535.2 S 1.457(ot a)386.905 535.2 R -.25(va)-.2 G 1.457(ilable for use by shell).25 F (scripts.)72 547.2 Q F1 2.5(4.3.5. New)72 571.2 R(Shell V)2.5 E(ariables)-.92 E F0 .701(There are a number of con)97 586.8 R -.15(ve)-.4 G .701(nience v).15 F .701(ariables that bash interprets to mak)-.25 F 3.2(el)-.1 G .7(ife easier) 402.76 586.8 R 5.7(.T)-.55 G .7(hese include)453.59 586.8 R F1(FIGNORE)72 598.8 Q F0 3.973(,w)C 1.473(hich is a set of \214lename suf)132.363 598.8 R<8c78>-.25 E 1.474(es identifying \214les to e)-.15 F 1.474 (xclude when completing \214lenames;)-.15 F F1(HOSTTYPE)72 610.8 Q F0 3.03(,w)C .53(hich is automatically set to a string describing the type of hardw)139.21 610.8 R .53(are on which bash is cur)-.1 F(-)-.2 E .76(rently e)72 622.8 R -.15 (xe)-.15 G(cuting;).15 E F1(OSTYPE)3.26 E F0 3.26(,t)C 3.26(ow)191.76 622.8 S .76(hich bash assigns a v)207.24 622.8 R .761(alue that identi\214es the v)-.25 F .761(ersion of)-.15 F/F4 9/Times-Roman@0 SF(UNIX)3.261 E F0(it')3.261 E 3.261 (sr)-.55 G(unning)476.22 622.8 Q 1.354 (on \(great for putting architecture-speci\214c binary directories into the)72 634.8 R F1 -.74(PA)3.854 G(TH)-.21 E F0 1.354(\); and)B F1(IGNOREEOF)3.854 E F0 3.854(,w)C(hose)485.67 634.8 Q -.25(va)72 646.8 S .062 (lue indicates the number of consecuti).25 F .362 -.15(ve E)-.25 H .062 (OF characters that an interacti).15 F .362 -.15(ve s)-.25 H .062 (hell will read before e).15 F .062(xiting \255)-.15 F .114(an easy w)72 658.8 R .113(ay to k)-.1 F .113(eep yourself from being logged out accidentally)-.1 F 5.113(.T)-.65 G(he)344.285 658.8 Q F1(auto_r)2.613 E(esume)-.18 E F0 -.25(va) 2.613 G .113(riable alters the w).25 F(ay)-.1 E .409 (the shell treats simple command names: if job control is acti)72 670.8 R -.15 (ve)-.25 G 2.909(,a).15 G .409(nd this v)335.516 670.8 R .409 (ariable is set, single-w)-.25 F .409(ord simple)-.1 F .17(commands without re\ directions cause the shell to \214rst look for a suspended job with that name \ before start-)72 682.8 R(ing a ne)72 694.8 Q 2.5(wp)-.25 G(rocess.)118.13 694.8 Q EP %%Page: 9 9 %%BeginPageSetup BP %%EndPageSetup /F0 10/Times-Roman@0 SF 2.5(-9-)279.67 48 S/F1 10/Times-Bold@0 SF 2.5 (4.3.6. Brace)72 84 R(Expansion)2.5 E F0 .653(Since sh of)97 99.6 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 1.893(\(pathname e)72 111.6 R 1.893 (xpansion requires that the \214lenames e)-.15 F 1.892(xist\), bash implements) -.15 F/F2 10/Times-Italic@0 SF(br)4.392 E 1.892(ace e)-.15 F(xpansion)-.2 E F0 4.392(,ac)C(apability)469 111.6 Q(pick)72 123.6 Q .496(ed up from csh.)-.1 F .496(Brace e)5.496 F .496(xpansion is similar to pathname e)-.15 F .496 (xpansion, b)-.15 F .497(ut the strings generated need not)-.2 F 1.107 (correspond to e)72 135.6 R 1.107(xisting \214les.)-.15 F 3.607(Ab)6.107 G 1.107(race e)207.655 135.6 R 1.107(xpression consists of an optional)-.15 F F2 (pr)3.606 E(eamble)-.37 E F0 3.606(,f)1.666 G(ollo)419.286 135.6 Q 1.106 (wed by a pair of)-.25 F 2.809 (braces enclosing a series of comma-separated strings, and an optional)72 147.6 R F2(postamble)5.31 E F0 7.81(.T)1.666 G 2.81(he preamble is)440.06 147.6 R(pr\ epended to each string within the braces, and the postamble is then appended t\ o each resulting string:)72 159.6 Q/F3 10/Courier@0 SF 6($e)97 177.6 S (cho a{d,c,b}e)115 177.6 Q(ade ace abe)97 189.6 Q F1 2.5(4.3.7. Pr)72 219.6 R (ompt Customization)-.18 E F0 .077(One of the more popular interacti)97 235.2 R .376 -.15(ve f)-.25 H .076(eatures that bash pro).15 F .076 (vides is the ability to customize the prompt.)-.15 F(Both)72 247.2 Q F1(PS1) 3.305 E F0(and)3.305 E F1(PS2,)3.305 E F0 .805 (the primary and secondary prompts, are e)3.305 F .805 (xpanded before being displayed.)-.15 F -.15(Pa)5.805 G(rameter).15 E .324 (and v)72 259.2 R .324(ariable e)-.25 F .324 (xpansion is performed when the prompt string is e)-.15 F .323 (xpanded, so the v)-.15 F .323(alue of an)-.25 F 2.823(ys)-.15 G .323(hell v) 454.217 259.2 R(ariable)-.25 E .728(can be put into the prompt \(e.g.,)72 271.2 R F1($SHL)3.228 E(VL)-.92 E F0 3.228(,w)C .728(hich indicates ho)258.564 271.2 R 3.228(wd)-.25 G .729(eeply the current shell is nested\).)342.988 271.2 R (Bash)5.729 E 1.895 (specially interprets characters in the prompt string preceded by a backslash.) 72 283.2 R 1.895(Some of these backslash)6.895 F .874 (escapes are replaced with the current time, the date, the current w)72 295.2 R .874(orking directory)-.1 F 3.374(,t)-.65 G .874(he username, and the)416.958 295.2 R .781(command number or history number of the command being entered.)72 307.2 R .78(There is e)5.781 F -.15(ve)-.25 G 3.28(nab).15 G .78 (ackslash escape to)429.13 307.2 R .007 (cause the shell to change its prompt when running as root after an)72 319.2 R F2(su)2.507 E F0 5.007(.B)C .008(efore printing each primary prompt,)360.388 319.2 R .27(bash e)72 331.2 R .27(xpands the v)-.15 F(ariable)-.25 E F1(PR)2.77 E(OMPT_COMMAND)-.3 E F0 .269(and, if it has a v)2.77 F .269(alue, e)-.25 F -.15 (xe)-.15 G .269(cutes the e).15 F .269(xpanded v)-.15 F .269(alue as a)-.25 F .04(command, allo)72 343.2 R .041(wing additional prompt customization.)-.25 F -.15(Fo)5.041 G 2.541(re).15 G .041 (xample, this assignment causes the current user)311.964 343.2 R(,)-.4 E .99 (the current host, the time, the last component of the current w)72 355.2 R .989(orking directory)-.1 F 3.489(,t)-.65 G .989(he le)402.954 355.2 R -.15(ve) -.25 G 3.489(lo).15 G 3.489(fs)443.412 355.2 S .989(hell nesting,)454.121 355.2 R(and the history number of the current command to be embedded into the primar\ y prompt:)72 367.2 Q F3 6($P)97 385.2 S (S1='\\u@\\h [\\t] \\W\($SHLVL:\\!\)\\$ ')115 385.2 Q (chet@odin [21:03:44] documentation\(2:636\)$ cd ..)97 397.2 Q (chet@odin [21:03:54] src\(2:637\)$)97 409.2 Q F0 .619 (The string being assigned is surrounded by single quotes so that if it is e)72 430.8 R(xported,)-.15 E F1(SHL)3.119 E(VL)-.92 E F0 .619(will be updated)3.119 F(by a child shell:)72 442.8 Q F3 (chet@odin [21:13:35] src\(2:638\)$ export PS1)97 460.8 Q (chet@odin [21:17:40] src\(2:639\)$ bash)97 472.8 Q (chet@odin [21:17:46] src\(3:696\)$)97 484.8 Q F0(The)72 506.4 Q F1(\\$)2.5 E F0(escape is displayed as `)2.5 E(`)-.74 E F1($)A F0 1.48 -.74('' w)D (hen running as a normal user).74 E 2.5(,b)-.4 G(ut as `)342.08 506.4 Q(`)-.74 E F1(#)A F0 1.48 -.74('' w)D(hen running as root.).74 E F1 2.5(4.3.8. POSIX)72 530.4 R(Mode)2.5 E F0 .46(Although bash is intended to be POSIX.2 compliant, t\ here are areas in which the def)97 546 R .46(ault beha)-.1 F .46(vior is)-.2 F 1.168(not compatible with the standard.)72 558 R -.15(Fo)6.169 G 3.669(ru).15 G 1.169(sers who wish to operate in a strict POSIX.2 en)238.85 558 R 1.169 (vironment, bash)-.4 F .61(implements a)72 570 R F2 .61(POSIX mode)3.11 F F0 5.61(.W)C .61(hen this mode is acti)199.42 570 R -.15(ve)-.25 G 3.109(,b).15 G .609(ash modi\214es its def)303.727 570 R .609(ault operation where it dif)-.1 F(fers)-.25 E .066(from POSIX.2 to match the standard.)72 582 R .067 (POSIX mode is entered when bash is started with the)5.066 F F1 .067(-o posix) 2.567 F F0(option)2.567 E .382(or when)72 594 R F1 .382(set -o posix)2.882 F F0 .381(is e)2.881 F -.15(xe)-.15 G 2.881(cuted. 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F)72 84 R(eatur)-.25 E(es Unique to ksh)-.18 E F0 .177 (Ksh includes a number of features not in the currently-released v)97 99.6 R .178(ersion of bash, v)-.15 F .178(ersion 1.14.)-.15 F(Unless)5.178 E .822 (noted, none of these features is in the POSIX.2 standard.)72 111.6 R .821 (Where appropriate the equi)5.821 F -.25(va)-.25 G .821(lent bash features).25 F(are noted.)72 123.6 Q F1 2.5(4.4.1. The)72 147.6 R(ksh Language)2.5 E F0 2.955(An)97 163.2 S .955 -.25(ew c)112.175 163.2 T .455(ompound command folds) .25 F F1(test)2.955 E F0 .456(into the ksh language, delimited by the reserv) 2.955 F .456(ed w)-.15 F(ords)-.1 E F1([[)2.956 E F0(and)2.956 E F1(]])72 175.2 Q F0 5.726(.T)C .726(he syntax is identical to)92.996 175.2 R F1(test)3.225 E F0 .725(with a fe)3.225 F 3.225(wc)-.25 G .725 (hanges: for instance, instead of)262.855 175.2 R F1<ad61>3.225 E F0(and)3.225 E F1<ad6f>3.225 E F0(,)A F1(&&)3.225 E F0(and)3.225 E/F2 10/Symbol SF<efef> 3.225 E F0(are)3.225 E 3.32(used. The)72 187.2 R -.1(wo)3.32 G .82(rds between) .1 F F1([[)3.32 E F0(and)3.32 E F1(]])3.32 E F0 .82(are not processed for w) 3.32 F .82(ord splitting or \214lename generation.)-.1 F .82(The ne)5.82 F(w) -.25 E .926 (command does pattern matching as well as string comparison, a la the)72 199.2 R F1(case)3.425 E F0 3.425(command. This)3.425 F(ne)3.425 E 3.425(wc)-.25 G (ontrol)480.11 199.2 Q .165(structure does ha)72 211.2 R .465 -.15(ve t)-.2 H .165(he adv).15 F .166(antage of reducing common ar)-.25 F .166 (gument problems encountered using test \(e.g.)-.18 F F1(test)2.666 E ("$string")72 223.2 Q F0 2.928(,w)C(here)125.748 223.2 Q F1($string)2.928 E F0 -.15(ex)2.928 G .428(pands to).15 F F1<ad66>2.928 E F0 .428(\), b)B .428 (ut at the cost of bloating the language.)-.2 F .427(The POSIX.2 test algo-) 5.427 F 2.752(rithm that bash uses, along with some programmer care, alle)72 235.2 R 2.752(viates those problems in a backw)-.25 F(ards-)-.1 E .854 (compatible w)72 247.2 R .853(ay with no additions to the language.)-.1 F .853 (The one capability of)5.853 F F1 .853([[ ]])3.353 F F0 .853(not a)3.353 F -.25 (va)-.2 G .853(ilable in bash is its).25 F(ability to test whether an indi)72 259.2 Q(vidual)-.25 E F1(set \255o)2.5 E F0(option is turned on or of)2.5 E(f.) -.25 E .339(Other parts of the ksh language are not common to bash.)97 274.8 R (The)5.34 E F1(\(\(...\)\))2.84 E F0(operator)5.34 E 2.84(,e)-.4 G(qui)419.33 274.8 Q -.25(va)-.25 G .34(lent to).25 F F1 .34(let "...")2.84 F F0(,)A .197 (is unique to ksh, as are the concept of co-processes and the)72 286.8 R F1 (time)2.697 E F0 -.1(ke)2.696 G(yw)-.05 E .196 (ord to time commands and pipelines.)-.1 F F1 2.5(4.4.2. Functions)72 310.8 R (and Aliases)2.5 E F0 1.022(The K)97 326.4 R 1.022(orn shell has)-.35 F/F3 10 /Times-Italic@0 SF(autoloaded)3.522 E F0 3.522(functions. A)3.522 F 1.022 (function mark)3.522 F 1.022(ed as)-.1 F F3(autoload)3.522 E F0 1.022 (is not de\214ned until it is)5.188 F 1.042(\214rst e)72 338.4 R -.15(xe)-.15 G 3.542(cuted. When).15 F 1.042(such a function is e)3.542 F -.15(xe)-.15 G 1.042 (cuted, a search is made through the directories in).15 F F1(FP)3.541 E -.95 (AT)-.74 G(H).95 E F0(\(a)3.541 E .27 (colon-separated list of directories similar to)72 350.4 R F1 -.74(PA)2.77 G (TH)-.21 E F0 2.77(\)f)C .27(or a \214le with the same name as the function.) 285.78 350.4 R .27(That \214le)5.27 F .548(is then read in as with the)72 362.4 R F1(.)3.881 E F0 .547(command; presumably the function is de\214ned therein.) 3.047 F .547(There is a pair of shell)5.547 F .886 (functions included in the bash distrib)72 374.4 R .886(ution \()-.2 F F3 -.2 (ex)C(amples/functions/autoload).2 E F0 5.886(\)t)C .886(hat pro)378.35 374.4 R .886(vide much of this func-)-.15 F (tionality without changing the shell itself.)72 386.4 Q .116 (Ksh functions are scoped in such a w)97 402 R .116(ay that the en)-.1 F .116 (vironment in which the)-.4 F 2.616(ya)-.15 G .116(re e)405.144 402 R -.15(xe) -.15 G .115(cuted is closer to a).15 F .827(shell script en)72 414 R 3.327 (vironment. Bash)-.4 F .827(uses the POSIX.2 scoping rules, which mak)3.327 F 3.327(et)-.1 G .827(he function e)392.517 414 R -.15(xe)-.15 G .828(cution en) .15 F(vi-)-.4 E 1.2(ronment an e)72 426 R 1.2(xact cop)-.15 F 3.7(yo)-.1 G 3.7 (ft)174.86 426 S 1.199(he shell en)184.67 426 R 1.199 (vironment with the replacement of the shell')-.4 F 3.699(sp)-.55 G 1.199 (ositional paramters)426.421 426 R(with the function ar)72 438 Q 2.5 (guments. K)-.18 F (orn shell functions do not share options or traps with the in)-.35 E -.2(vo) -.4 G(king shell.).2 E .451(Ksh has)97 453.6 R F3(tr)2.951 E(ac)-.15 E -.1(ke) -.2 G(d).1 E F0 .452(aliases, which alias a command name to its full pathname.) 2.952 F .452(Bash has true command)5.452 F(hashing.)72 465.6 Q F1 2.5 (4.4.3. Arrays)72 489.6 R F0 .246 (Arrays are an aspect of ksh that has no real bash equi)97 505.2 R -.25(va)-.25 G 2.746(lent. The).25 F 2.746(ya)-.15 G .246(re easy to create and manipulate:) 371.42 505.2 R 1.637 (an array is created automatically by using subscript assignment \()72 517.2 R F1(name)A F0([)A F3(inde)A(x)-.2 E F0(]=)A F1 -.1(va)C(lue).1 E F0 1.637 (\), and an)B 4.137(yv)-.15 G(ariable)476.79 517.2 Q 1.967 (may be referred to as an array)72 529.2 R 6.967(.K)-.65 G 1.967(sh arrays, ho) 219.229 529.2 R(we)-.25 E -.15(ve)-.25 G 2.767 -.4(r, h).15 H -2.25 -.2(av e).4 H(se)4.667 E -.15(ve)-.25 G 1.967(ral anno).15 F 1.967(ying limitations: the) -.1 F 4.466(ym)-.15 G 1.966(ay be)480.654 529.2 R(inde)72 541.2 Q -.15(xe)-.15 G 3.498(do).15 G .998(nly up to 512 or 1024 elements, depending on ho)111.858 541.2 R 3.498(wt)-.25 G .999(he shell is compiled, and there is only the) 330.188 541.2 R(clumsy)72 553.2 Q F1 .223(set -A)2.723 F F0 .223 (to assign a list of v)2.723 F .223(alues sequentially)-.25 F 5.223(.D)-.65 G .223(espite these limits, arrays are useful, if underutilized)293.31 553.2 R (by shell programmers.)72 565.2 Q F1 2.5(4.4.4. Builtin)72 589.2 R(Commands)2.5 E F0 .112(Some of the b)97 604.8 R .112(uiltin commands ha)-.2 F .412 -.15 (ve b)-.2 H .112(een e).15 F .112(xtended or are ne)-.15 F 2.612(wi)-.25 G 2.613(nk)351.402 604.8 S 2.613(sh. 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History)72 235.2 R F0 (Finally)97 250.8 Q 3.372(,t)-.65 G .872(he ksh history implementation dif) 133.342 250.8 R .871(fers slightly from bash.)-.25 F .871 (Each instance of bash k)5.871 F .871(eeps the)-.1 F .633 (history list in memory and of)72 262.8 R .633(fers options to the)-.25 F F1 (history)3.133 E F0 -.2(bu)3.133 G .634 (iltin to write the list to or read it from a named).2 F 3.216(\214le. Ksh)72 274.8 R -.1(ke)3.216 G .716 (eps the history in a \214le, which it accesses each time a command is sa).1 F -.15(ve)-.2 G 3.215(dt).15 G 3.215(oo)426.445 274.8 S 3.215(rr)439.66 274.8 S (etrie)449.535 274.8 Q -.15(ve)-.25 G 3.215(df).15 G(rom)487.89 274.8 Q .338 (the history)72 286.8 R 5.338(.K)-.65 G .338 (sh history \214les may be shared among dif)129.246 286.8 R .338 (ferent concurrent instances of ksh, which could be a)-.25 F (bene\214t to the user)72 298.8 Q(.)-.55 E F1 2.5(5. F)72 322.8 R(eatur)-.25 E (es in Bash-2.0)-.18 E F0 .657(The ne)97 338.4 R .657 (xt release of bash, 2.0, will be a major o)-.15 F -.15(ve)-.15 G 3.157 (rhaul. It).15 F .656(will include man)3.157 F 3.156(yn)-.15 G 1.156 -.25(ew f) 419.532 338.4 T .656(eatures, for both).25 F .705(programming and interacti)72 350.4 R 1.005 -.15(ve u)-.25 H 3.205(se. Redundant).15 F -.15(ex)3.205 G .705 (isting functions will be remo).15 F -.15(ve)-.15 G 3.206(d. There).15 F .706 (are se)3.206 F -.15(ve)-.25 G .706(ral cases).15 F 1.34(where bash treats a v) 72 362.4 R 1.34(ariable specially to enable functionality a)-.25 F -.25(va)-.2 G 1.34(ilable another w).25 F 1.34(ay \()-.1 F F1($nolinks)A F0(vs.)3.84 E F1 1.34(set -o)3.84 F(ph)72 374.4 Q(ysical)-.15 E F0 2.5(,f)C(or e)115.19 374.4 Q (xample\); the special treatment of the v)-.15 E(ariable name will be remo)-.25 E -.15(ve)-.15 G(d.).15 E F1 2.5(5.1. 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This).2 F(ne)2.761 E 2.761(ws)-.25 G(yntax)481.78 450 Q .441(has the form)72 462 R F2(name)2.941 E F0(=\()A F2(value1)A F0(...) 2.941 E F2(valueN)2.941 E F0 .441(\), where each)B F2(value)2.942 E F0 .442 (has the form [)4.608 F F2(subscript)A F0(]=)A F2(string)A F0 5.442(.O)C .442 (nly the)449.776 462 R F2(string)2.942 E F0 1.395(is required.)72 474 R 1.395 (If the optional brack)6.395 F 1.395(ets and)-.1 F F2(subscript)3.894 E F0 1.394(are included, that inde)3.894 F 3.894(xi)-.15 G 3.894(sa)388.714 474 S 1.394(ssigned to, otherwise the)400.938 474 R(inde)72 486 Q 3.656(xo)-.15 G 3.656(ft)102.726 486 S 1.156(he element assigned is the last inde)112.492 486 R 3.657(xa)-.15 G 1.157(ssigned to by the statement plus one.)272.917 486 R(Inde) 6.157 E 1.157(xing starts at)-.15 F 2.73(zero. The)72 498 R .23 (same syntax is accepted by)2.73 F F1(declar)2.73 E(e)-.18 E F0 5.229(.I)C(ndi) 269.159 498 Q .229(vidual array elements may be assigned to using the ksh)-.25 F F2(name)72 510 Q F0([)A F2(subscript)A F0(]=)A F2(value)A F0(.)A F1 2.5 (5.2. Dynamic)72 534 R(Loading)2.5 E F0 .348(On systems that support the)97 549.6 R F2(dlopen)2.848 E F0 .349(\(3\) library function, bash-2.0 will allo)B 2.849(wn)-.25 G .849 -.25(ew b)407.504 549.6 T .349(uiltins to be loaded).05 F .049(into a running shell from a shared object \214le.)72 561.6 R .049(The ne) 5.049 F 2.549(wb)-.25 G .049(uiltins will ha)298.999 561.6 R .348 -.15(ve a)-.2 H .048(ccess to the rest of the shell f).15 F(acil-)-.1 E .649(ities, b)72 573.6 R .649(ut programmers will be subject to a fe)-.2 F 3.149(ws)-.25 G .649 (tructural rules.)269.591 573.6 R .65(This will be pro)5.65 F .65 (vided via a ne)-.15 F 3.15(wo)-.25 G .65(ption to)472.51 573.6 R F1(enable)72 585.6 Q F0(.)A F1 2.5(5.3. 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V)72 144 R(ariables and V)-.92 E(ariable Expansion)-.92 E F0 .047 (Bash-2.0 will implement se)97 159.6 R -.15(ve)-.25 G .048(ral ne).15 F 2.548 (wv)-.25 G .048(ariable e)252.988 159.6 R 2.548(xpansions. These)-.15 F .048 (will answer se)2.548 F -.15(ve)-.25 G .048(ral of the most per).15 F(-)-.2 E .213(sistant requests for ne)72 171.6 R 2.713(wf)-.25 G 2.713(eatures. It) 172.582 171.6 R .213(will be possible to `)2.713 F .212(`indirectly reference') -.74 F 2.712('av)-.74 G .212(ariable with an e)398.534 171.6 R(xpansion,)-.15 E (lik)72 183.6 Q 3.01(eu)-.1 G(sing)94.91 183.6 Q/F3 10/Courier@0 SF .51 (eval \\$${name})3.01 F F0 .51(to reference a v)3.01 F .51(ariable named by) -.25 F F3(${name})3.01 E F0 5.51(.E)C .51(xpansions will be a)394.32 183.6 R -.25(va)-.2 G(ilable).25 E .462(to retrie)72 195.6 R .762 -.15(ve s)-.25 H .462 (ubstrings of v).15 F .461(ariables in an)-.25 F F1(awk)2.961 E F0(-lik)A 2.961 (em)-.1 G .461(anner: starting at a speci\214c inde)277.692 195.6 R .461 (x, retrie)-.15 F .461(ving some num-)-.25 F .941 (ber of characters or the rest of the string.)72 207.6 R .941 (It will be possible to retrie)5.941 F 1.241 -.15(ve s)-.25 H .941 (equences of array elements lik).15 F(e)-.1 E .354(this, too.)72 219.6 R .354 (It w)5.354 F .354(ould be nice to ha)-.1 F .654 -.15(ve a w)-.2 H .354 (ay to replace portions of a v).05 F .353 (ariable matching a pattern the same w)-.25 F(ay)-.1 E(leading or trailing sub\ strings are presently stripped; that capability may be a)72 231.6 Q -.25(va)-.2 G(ilable.).25 E .453(Another ne)97 247.2 R 2.953(we)-.25 G .453 (xpansion will pro)156.376 247.2 R .453(vide a w)-.15 F .454 (ay to create strings containing arbitrary characters, which is)-.1 F(incon)72 259.2 Q -.15(ve)-.4 G 1.636(nient in the current v).15 F 4.136(ersion. W)-.15 F 1.635(ords of the form $')-.8 F F1(string)A F0 4.135('w)C 1.635(ill e)355.145 259.2 R 1.635(xpand to)-.15 F F1(string)4.135 E F0 1.635(with backslash-)4.135 F 1.231(escaped characters in)72 271.2 R F1(string)3.731 E F0 1.231 (replaced as speci\214ed by the ANSI C standard.)3.731 F 1.232 (As with other single-quoted)6.232 F (shell strings, the only character that may not appear in)72 283.2 Q F1(string) 2.5 E F0(is a single quote.)2.5 E 1.436(The shell v)97 298.8 R 1.436 (ariables will change also.)-.25 F 3.936(An)6.436 G 1.936 -.25(ew va)272.052 298.8 T(riable).25 E F2(HISTIGNORE)3.936 E F0 1.435(will supersede)3.936 F F2 (HISTCON-)3.935 E(TR)72 310.8 Q(OL)-.3 E F0(.)A F2(HISTIGNORE)5.327 E F0 .327 (is the history analogy of)2.827 F F2(FIGNORE)2.828 E F0 2.828(:ac)C .328 (olon-separated list of patterns specifying)339.938 310.8 R 1.082 (commands to omit from the history list.)72 322.8 R 1.081 (The special pattern '&' will match the pre)6.081 F 1.081 (vious history line, to)-.25 F(pro)72 334.8 Q 1.568(vide the)-.15 F F2 (HISTCONTR)4.068 E(OL)-.3 E F1(ignor)4.068 E(edups)-.37 E F0(beha)5.734 E(vior) -.2 E 6.568(.M)-.55 G(an)303.546 334.8 Q 4.069(yv)-.15 G 1.569 (ariables which modify the shell')326.655 334.8 R 4.069(sb)-.55 G(eha)474.21 334.8 Q(vior)-.2 E .395(will lose their special meaning.)72 346.8 R -1.11(Va) 5.395 G .395(riables such as)1.11 F F2(notify)2.895 E F0(and)2.895 E F2(noclob) 2.895 E(ber)-.1 E F0 .395(which pro)2.895 F .395(vide functionality a)-.15 F -.25(va)-.2 G(il-).25 E .931 (able via other mechanisms will no longer be treated specially)72 358.8 R 5.931 (.O)-.65 G .931(ther v)340.06 358.8 R .932(ariables will be folded into)-.25 F F2(shopt)3.432 E F0(.)A(The)72 370.8 Q F2(history_contr)5.519 E(ol)-.18 E F0 (and)5.519 E F2(hostname_completion_\214le)5.519 E F0 -.25(va)5.519 G 3.019 (riables, superseded by).25 F F2(HISTCONTR)5.518 E(OL)-.3 E F0(and)5.518 E F2 (HOSTFILE)72 382.8 Q F0(respecti)2.5 E -.15(ve)-.25 G(ly).15 E 2.5(,w)-.65 G (ill be remo)185.12 382.8 Q -.15(ve)-.15 G(d.).15 E F2 2.5(5.5. Readline)72 406.8 R F0(Naturally)97 422.4 Q 2.94(,t)-.65 G .44(here will be impro)142.34 422.4 R -.15(ve)-.15 G .441(ments to readline as well.).15 F .441 (All of the POSIX.2)5.441 F F1(vi)2.941 E F0 .441(-mode editing com-)B .33 (mands will be implemented; missing commands lik)72 434.4 R 2.829(e`)-.1 G .329 (m' to sa)290.599 434.4 R .629 -.15(ve t)-.2 H .329 (he current cursor position \().15 F F1(mark)A F0 2.829(\)a)C .329(nd the) 478.951 434.4 R .36(`@' command for macro e)72 446.4 R .36(xpansion will be a) -.15 F -.25(va)-.2 G 2.861(ilable. The).25 F .361 (ability to set the mark and e)2.861 F .361(xchange the current)-.15 F .764 (cursor position \()72 458.4 R F1(point)A F0 3.264(\)a)C .764 (nd mark will be added to the readline emacs mode as well.)170.672 458.4 R .763 (Since there are com-)5.764 F .196 (mands to set the mark, commands to manipulate the re)72 470.4 R .197 (gion \(the characters between the point and the mark\))-.15 F .111(will be a) 72 482.4 R -.25(va)-.2 G 2.611(ilable. Commands).25 F(ha)2.611 E .411 -.15 (ve b)-.2 H .11 (een added to the readline emacs mode for more complete ksh compati-).15 F (bility)72 494.4 Q 2.5(,s)-.65 G(uch as the C-])101.36 494.4 Q F1(c)A F0 (character search command.)2.5 E F2 2.5(5.6. Con\214guration)72 518.4 R F0 .318 (Bash w)97 534 R .318 (as the \214rst GNU program to completely autocon\214gure.)-.1 F .319 (Its autocon\214guration mechanism pre-)5.319 F(dates)72 546 Q F1(autoconf)4.07 E F0 4.07(,t)C 1.569 (he current GNU con\214guration program, and needs updating.)140.97 546 R 1.569 (Bash-2.0 may include an)6.569 F .603 (autoconf-based con\214guration script, if necessary ne)72 558 R 3.103(wf)-.25 G .603(unctionality can be added to autoconf, or its limita-)294.476 558 R (tions bypassed.)72 570 Q F2 2.5(5.7. Miscellaneous)72 594 R F0 1.632 (The POSIX mode will be impro)97 609.6 R -.15(ve)-.15 G 4.131(di).15 G 4.131 (nb)254.26 609.6 S 1.631(ash-2.0; it will pro)268.391 609.6 R 1.631 (vide a more complete superset of the)-.15 F(POSIX standard.)72 621.6 Q -.15 (Fo)5 G 2.5(rt).15 G(he \214rst time, bash will recognize the e)163.79 621.6 Q (xistance of the POSIX.2)-.15 E F1(special)2.5 E F0 -.2(bu)2.5 G(iltins.).2 E 2.627(An)97 637.2 S .627 -.25(ew t)111.847 637.2 T .127(rap v).25 F(alue,)-.25 E F2(DEB)2.627 E(UG)-.1 E F0 2.627(,w)C .128(ill be present, as in ksh.)218.405 637.2 R .128(Commands speci\214ed with a)5.128 F F2(DEB)2.628 E(UG)-.1 E F0 .128(trap will)2.628 F 1.908(be e)72 649.2 R -.15(xe)-.15 G 1.908 (cuted after e).15 F -.15(ve)-.25 G 1.908(ry simple command.).15 F 1.908 (Since this mak)6.908 F 1.908(es shell script deb)-.1 F 1.908 (uggers possible, I hope to)-.2 F(include a bash deb)72 661.2 Q (ugger in the bash-2.0 release.)-.2 E F2 2.5(6. A)72 685.2 R -.1(va)-1 G (ilability).1 E F0 5.997(The current v)97 700.8 R 5.997(ersion of bash is a) -.15 F -.25(va)-.2 G 5.998(ilable for anon).25 F 5.998 (ymous FTP from prep.ai.mit.edu as)-.15 F F1(/pub/gnu/bash-1.14.2.tar)72 712.8 Q(.gz)-1.11 E F0(.)1.666 E EP %%Page: 13 13 %%BeginPageSetup BP %%EndPageSetup /F0 10/Times-Roman@0 SF 2.5(-1)277.17 48 S 2.5(3-)288 48 S/F1 10/Times-Bold@0 SF 2.5(7. Conclusion)72 84 R F0 .755(This paper has presented an o)97 99.6 R -.15(ve)-.15 G(rvie).15 E 3.255(wo)-.25 G 3.255(fb)259.27 99.6 S .755 (ash, compared its features with those of other shells, and)270.855 99.6 R (hinted at features in the ne)72 111.6 Q(xt release, bash-2.0.)-.15 E .483 (Bash is a solid replacement for sh.)97 127.2 R .483(It is suf)5.483 F .483 (\214ciently portable to run on nearly e)-.25 F -.15(ve)-.25 G .484(ry v).15 F .484(ersion of)-.15 F/F2 9/Times-Roman@0 SF(UNIX)2.984 E F0 .514 (from 4.3 BSD to SVR4.2, and se)72 139.2 R -.15(ve)-.25 G(ral).15 E F2(UNIX) 3.013 E F0 -.1(wo)3.013 G(rkalik).1 E .513(es, and rob)-.1 F .513 (ust enough to replace sh on most of those)-.2 F .771(systems, It is v)72 151.2 R .771(ery close to POSIX.2-conformant in POSIX mode, and is getting f)-.15 F (aster)-.1 E 5.771(.I)-.55 G 3.272(ti)436.684 151.2 S 3.272(sn)445.516 151.2 S .772(ot, unfortu-)457.678 151.2 R(nately)72 163.2 Q 2.663(,g)-.65 G .163 (etting smaller)105.953 163.2 R 2.663(,b)-.4 G .163(ut there are man)170.399 163.2 R 2.663(yo)-.15 G .163(ptional features.)248.101 163.2 R .163(It is v) 5.163 F .162(ery easy to b)-.15 F .162(uild a small subset to use as)-.2 F 2.5 (ad)72 175.2 S(irect replacement for /bin/sh.)83.94 175.2 Q .909 (Bash has thousands of users w)97 190.8 R .909(orldwide, all of whom ha)-.1 F 1.209 -.15(ve h)-.2 H .91(elped to mak).15 F 3.41(ei)-.1 G 3.41(tb)409.34 190.8 S(etter)420.53 190.8 Q 5.91(.A)-.55 G .91(nother testa-)453.38 190.8 R (ment to the bene\214ts of free softw)72 202.8 Q(are.)-.1 E F1 2.5(8. Refer)72 226.8 R(ences)-.18 E F0 .432([1] S. R. Bourne, `)72 242.4 R .432(`UNIX T)-.74 F .432(ime-Sharing System:)-.35 F .431(The UNIX Shell')5.431 F(',)-.74 E/F3 10 /Times-Italic@0 SF .431(Bell System T)2.931 F(ec)-.92 E .431(hnical J)-.15 F (ournal)-.25 E F0 2.931(,5)C(7\(6\),)484.84 242.4 Q (July-August, 1978, pp. 1971-1990.)72 254.4 Q .736([2] Morris Bolsk)72 270 R 3.237(ya)-.15 G .737(nd Da)153.22 270 R .737(vid K)-.2 F(orn,)-.35 E F3 .737 (The K)3.237 F .737(ornShell Command and Pr)-.4 F -.1(og)-.45 G -.15(ra).1 G .737(mming Langua).15 F -.1(ge)-.1 G F0 3.237(,P).1 G .737(rentice Hall,) 453.833 270 R(1989.)72 282 Q .142([3] Bill Jo)72 297.6 R 1.442 -.65(y, A)-.1 H 2.642(nI).65 G .141(ntroduction to the C Shell,)140.428 297.6 R F3 .141 (UNIX User')2.641 F 2.641(sS)-.4 G .141(upplementary Documents)309.346 297.6 R F0 2.641(,U)C(ni)424.328 297.6 Q -.15(ve)-.25 G .141(rsity of Califor).15 F(-) -.2 E(nia at Berk)72 309.6 Q(ele)-.1 E 1.3 -.65(y, 1)-.15 H(986.).65 E .283 ([4] IEEE,)72 325.2 R F3 .283(IEEE Standar)2.783 F 2.783(df)-.37 G .283 (or Information T)179.692 325.2 R(ec)-.92 E(hnolo)-.15 E .283(gy -- P)-.1 F .283(ortable Oper)-.8 F .283(ating System Interface \(POSIX\) P)-.15 F(art)-.8 E(2: Shell and Utilities)72 337.2 Q F0 2.5(,1)C(992.)165.06 337.2 Q F1 2.5 (9. A)72 361.2 R(uthor Inf)-.5 E(ormation)-.25 E F0 .937(Chet Rame)97 376.8 R 3.437(yi)-.15 G 3.437(sas)153.724 376.8 S(oftw)172.818 376.8 Q .936 (are engineer w)-.1 F .936(orking at Case W)-.1 F .936(estern Reserv)-.8 F 3.436(eU)-.15 G(ni)393.43 376.8 Q -.15(ve)-.25 G(rsity).15 E 5.936(.H)-.65 G 3.436(eh)443.036 376.8 S .936(as a B.S. in)455.912 376.8 R .072 (Computer Engineering and an M.S. in Computer Science, both from CWR)72 388.8 R 2.573(U. He)-.4 F .073(has been w)2.573 F .073(orking on bash)-.1 F (for six years, and the primary maintainer for one.)72 400.8 Q EP %%Trailer end %%EOF