so this is a preview of a conferencetalk I've got coming up so we don'tnormally think too much these days aboutwhat Unix means you know in 2023 mostUnix systems are actually running somekind of Linux which includes you knowmodern tools modern commands that werejust Unthinkable when Unix hit the scenein the early 1970s but here we are someyou know 50 years later and Unix isstill going on and so I wanted to goback into Unix history and sort ofdemonstrate first hand what it was liketo use an original Unix now to do that Ineed to talk a little bit about historyhere so the first version of what wewould Call Unix came out in 1971 thatwas Unix first edition and that was thefirst one to run on the PDP 11 computerthe second edition came out uh in in1972 and that was the first version thatincluded a c compiler because that'swhen the C programming language was bornthe Third Edition included features thatwe kind of take for granted today andthat was the first version that hadpipes and that's where you could takeone command and send the output directlyto another command before that you hadto Output uh to a file and then you hadto read that file into another programbut now with pipes you could string onecommand into the nextalso that later that same year wasunix's fourth edition that was reallythe first time people got to see Unix uhout Beyond much Beyond Bell Labs uhfifth edition was really meant forhigher education the sixth edition wasthe one where they started to seecommercial licenses1979 things started to slow down alittle bit because it's not really uhsomething that Bell devs wanted to focuson in terms of operating systemdevelopment but this is where we got theBourne shell in seventh edition 8thEdition was again really meant forhigher education ninth Edition was neverreally released it was kind of aconceptual release in 1986 and then 1989was the 10th edition that was the lastversion of research Unix now what was ineach one of these versions so uh theUnix first edition which came outNovember 1971included a bunch of commands that wewould recognize uh today I'm going tohighlight only a couple of things inhere uh Roth by the way was was in thisand so Roth uh was the first uh programthat would allow you to uh typeset textbefore this there was another programthat was known in the competing circlescalled runoff and that was a programthat uh got its name from I'm going torun off a paper I'm going to run off adocument it was just a quick way toformat a document Roth was meant to besort of a simplified version of whatrunoff provided and so that's why I gotthe short name Roth later it was well aswe'll see there was a run an N Roth andthat was the new version of rock andeven later there was a t-roth and thatwas when Bell Labs purchased a phototype Center and they were able to now dotypesetted version of Roth but thisversion also had a Fortran compilerobviously that was Fortran 66 and ofcourse a basic environment Unix secondedition 1972 this was the first timethat they updated Roth to now become nRoth and so we can actually start towrite documents using a more familiarenvironment uh with uh with mrothalso as I said earlier this is the firstversion that included the C compilernow I actually have a copy of the Unixsecond edition manual and so this is thecover page for that manual in 1972. andthe table of contents shows you all thedifferent commands that were availableto you I've only grabbed the first twopages here which shows uh section one ofthe manual all the different commandsthat you could runUnix Third Edition is what I'm going toshow off because that was that was 50years ago as I do this video and so thatincluded the first C debugger as Imentioned also included pipes this isalso the first time that they split offbin from user bin user was usuallymounted as a second hard drive and sothis allows you to split the commandsacross core system commands and thenthings were sort of more user orientednow as we look at the the manual forthat this is the manual from 1973 againthis is the cover page you can see allthe different commands that wereavailable to you now in this video we'realso going to explore nroff and so thatis uh part of the uh Enix Third Editionuh and to look at some of the uh youknow what we're talking about in termsof emulating this old environment youknow what were people using to interactwith Unix back at that time well this isthe PDP 11 that they were using I thinkthis was taken around the time of Unixfirst editionand the teletype terminal is what KenThompson is using there and that isliterally a big roll of paper and as youpress down on these Keys it would typeout on the piece of paper and when thecomputer had output for you and type itback out onto that piece of paper and sothat was the first terminal a teletypeterminalnow over time you started to getelectronic terminals these video displayunits now granted this is a vt100terminal which is uh long after uh Unix3rd Edition but I'm showing it onlybecause it was probably arguably the themost popular uh video terminal of itsera and but in the early 19 early to mid1970s after we moved off of teletype youstarted to get video display units whichlooked not not unlike what you're seeinghere and so when I do this demonstrationof what Unix might have looked like 50years ago I'm going to use a videodisplay terminal that looks somethinglike this now when we talk about aterminal emulator or a terminal windowon your Unix machine your Linux machinethis is actually what it's emulatingit's emulating a system like this theold glass Terminals and one program thatI like that actually does a pretty goodjob of emulating what it felt like touse a glass terminal is cool retro termand that's what I've got here and sothis is emulating a glass terminaluh for those of you who are curious uhif I bring up the menu here you can seethat I'm running in uh Apple 2 mode andI'm running in full screen andthis is set up right now to have uh justdo an echo on columns this is set up tobe an 88 column displayat 24 lines and so why did I pick thiswell one I I wanted to be zoomed in farenough that I could make it look kind oflike an original terminal system thoseterminal systems were 80 columns wideand 25 lines tall though usually thelast line was observed for some sort ofterminal display or terminal status soan 80 by 24 is closest that I can get toemulating an original uh you know glassterminal and so 88 by 24is pretty close now I'm running it inthis Apple 2 because this is what givesme a font that is big enough that Ithink it'll show up well on YouTube nowI've also set up my terminal to emulatea vt100 of the Linux terminal can allemulate vt100so what were some things that peoplemight have done on a Unix machine backat that time and so one thing that aperson might have done is to write uhprograms and write documents while wedidn't have VI in this era VI didn'tcome along until much later and so theeditor that everyone is using at thetime was an editor called Edand this is the line editor if you everlook into original Unix systems this wasused all over the place until VI camealong now I'm going to use add them toedit my my work here so if you ever wantto see what Ed looks like this is it solet's go ahead and edit a a program aFortran program and I don't haveanything in this directory right nowlet's edit a new program in Fortran andof course we'll do this in Fortran 66.now I've got a Fortran 77 compiler onthe system and actually all it really isuh I've got aI've got a Fortran 77 shell script whichis really uh aan alias basically to the gnu Fortrancompiler which will happily compile uhFortran 77 and backwards compatibleprograms so we can use this to compileeven though it's f77 and Unix Edition 3used Fortran 66. we can still use thisto sort of simulate the work that we'vedone back then so let's go ahead andedit a program so the program I'm goingto edit here is let's do a clear screenuh clear the we're going toumwrite a simple Fortran program that willdo some trajectory data for us and so Iwas a physics undergraduate and this issomething that I would have done all thetime so I'm going to do a new programI'm going to call Ed and I'm going toname this program drop dot fand there's no file here yet so as Isave this file later on I'll be creatinga new file so let's go ahead and startour prompt and so I'm going to do acapital P and that will turn on theprompt otherwise you just kind of haveto know where you are so the prompt hereis just a star an asterisk so let's goahead and since this is an empty filelet's go ahead and insert some new linesso Fortran is a column sensitive and soyou need to be careful what columnyou're in so one two three four five sixso now I'm in column seven I'm going touse a called this program dropand what are we doing in this programlet's let's do some uh some documentinghere so let's make a comment uh and sothis is uh going to simulate uhtrajectory dataand so the formula for trajectory is Xas a function of time is X 0 plus v zerotimes time plus one half a t squared andso when you do exponents and four trainit's the double star and so that is thetrajectory data but if we make theassumptionthat x 0 is 0 and that V 0 is 0. this istypical for uh some sort of experimentwhere you'd want to get trajectory databasically how long does it take anobject to falland undergraduates who do this all thetime to kind of measure the accelerationdue to gravity and so if we make thatassumption then what we're ending upwith is uh X over any value of T isgoing to beuh just one half a tsquared now if we turn that aroundwe solve for T then how long does ittake when you drop uh any kind of objectlet's say just a in an undergraduate labit might be a steel ball and so if weinstall solve for T then I can do somesimple math here to say that t squaredis going to be equal to2xdivided by aor in other wordsT is going to be equal to the squareroot of 2x oops 2x divided by a and sothat's what we're going to be doing herewe're going to be doing a reversetrajectory here we're going to basicallysimulate how long it takes uh someobject let's say a ball to drop fromdifferent heights uh and when I was anundergraduate we'd use a photo gate andthat would give us some very accuratetimings for a for how long it would takea an object to drop from differentheights and we would probably move thisup at let's say 10 centimeter Heights orsomething like that and so that's whatwe're going to do here we're going toassimilate that and so we're going to dosix I need to have some variables hereso we'll do a double precisiondouble precision and then there's weneed to measure certainly X and we needto have t and we need to have theacceleration due to gravity and so I'lljust do that as G and then we probablyshould establish G as being 9.8and then we'll start Xat0.0 and I should have looked up before Idid this video If Fortran 66 had a doLoop and I can't remember if it did Ithink it did but we're gonna we're gonnamake our own Loop uh so let's do let'sdo this I think it's I think we'd wantto put our start of our Loop here and sowe want to calculate that for thatheight tis going to be equal tothe square root of 2.0 times x dividedby Gand if that's right then I should beable to print outthe values of How High we dropped itfrom and then how long it took to reachthe groundso that's what I want to do there andthen I want to now increment so I don'thave a do Loop I'm doing this without ado Loop so I'm just going to increment Xand so we'll say x is X Plus 0.1and then we're going to say as long as Xis less than let's say 1.05 I'm just I Icould do some other value but like 1.01or something like that I I don't want todo like less than 1.1 just because Idon't want there to be like drift in myuh my floating point so I always canlearn as an undergraduatemake this if you're doing a less than ofa comparison of a double Precision or areal value you should just go beyondslightly beyond what you're looking forso that's going to do there it's justslightly Beyond one meterand then we'll if it's less than that wecan then we can go back to go to 10.and if it uh has now exceeded one meterthen we can go ahead and end the programand so that should be correctuh and so I'm going to put a period inits own line and that tells Ed that I'vereached the end of my file I'm going togo ahead and write that to disk becauseI don't want to mess anything up andlet's look at the listing of my file sodo a one comma and then the end of thefile and we'll say number every lineand so that tells me that that is a 16line program and you can see the uh whatmy program looks like now it's it'sadded a tab in there from the left andso not now everything isn't uh leftJustified neatly if I want to do that Icould do one comma 16 let's say it lastline and then P to print it out and thenI can see my my full listing I alreadysaved the file so let's go ahead andquit and so if I compile that uh let'sdo uh in my case a program is called f77and we're going to save that as drop andthen there's drop that fand no errors so that's good and so if Ijust run drop then there it is so uhgoing at 0.1 increments uh droppinglet's say a ball uh not a surprise thatdropping it from zero gives you animmediate hits the ground uh and thengoing up that's how long it takes uh fora an object to hit the ground and so ifI were an undergraduate student this isa typical program that I might writelet'sum let's let's write a document thatdescribes this and so let's start a newdocument let's do clear and so let'sstart a new document we'll do it in theme macros because I like to use that nowwe don't have eqn that's that's theprogram that would appear later fort-roth to do equations and so we can'tdo equations in this but we can directlyformat a document to kind of simulateequations so we're going to do an ed ofa new file called uh well I'll just callit about.meand there's no file there so when I saveit it'll be saved in file let's go aheadand create a prompt and so as I insertsome new text uh let's uh if you watchthe other video about how to use me uhyou know how to do this and so we'regoing to do is we're going to create a atitle page right up at the top uh I alsolike to Define my headers and so let'ssay I wanted to have at the top uh wellI'll just put in left and center andthen right just so you can see a demo ofhow you'd create page headers and I canalso create a page footer and that wouldhave let's say left and then nothing inthe middle so I'm going to do two singlequotes there and we'll do a page numberon the right because anytime you use apercent uh in a header or footer that'llinsert the page numberuh and just so we can see that that'sactually left in a footer I'll actuallyjust sayum footer and then there's our pagenumber all right so that's that's whatwe'll see there uh and then on the coverpage I'm still on the cover page uh thetitle page let's go ahead and Centersome lines and so we'll go in the centeruh let's do the next three lines thatcould output it and it's blank linesdon't count so we're going to space downby we'll do three inches of spaceand then we'll put in a title which I'llmake bold and I'll say uh simple uhtrajectory uh dataand then we'll uh we'll space down anextra two linesand we'll put in the author so Jim halland then we'll space down an extra lineand then we'll uh we'll put in we'll puton the date we'll just say date and sothere I've got three lines of output soI've got the simple trajectory data is aone line of output and then my name andthen date so now it's those are that'sthe end of the three lines that getscentered dot CEand so now that I've done that I can nowuh do a page break or break page BP andnow the header and footer will now takeeffect and so let's let's also I like tonow do line spacing If I Was Anundergraduate student of two and nowlet's go ahead and just create somesection headings now I don't need anumber of these because I'm just goingto do a simple document so we'll do anun numbered heading dot uh that saysum introduction it doesn't have to be inquotes since I didn't end up writinganother word and then we'll do a a leftblock paragraphuh which I personally remember LP isalso a leading paragraph because if youlook at any textbook or any formal bookThe the first paragraph after a sectionheading is block paragraph to the leftis not doesn't have that temporaryindent dot PP would give me a temporaryindent dot LP does not so I'm going todo a leading paragraph after that I'mgoing to say uh this program uh or thispaper uh discussesuh aa Fortranprogramtosimulate thesimple trajectory motionof an objectthat has been droppeddifferentand then we'll do a paragraph in hereand we'll saythe the math I will say derivation uhI will sayuh assuming the the equation of motionand so this is where we get to be alittle tricky here so we're going to putin uh now I don't have eqn uh which isthe program for equations in in t-rothbecause this is still n Roth we don'thave qn yet so I need to do this on myown so I need to create uh and turn offfill so I'm going to do NF that willturn off filling no filland now I'm going to put in the equationof motion so you can just do a couple ofspaces in here so basically anythingbetween NF and the next fi which is whatI'm going to do later on I'll do an fiand that will turn filling back onanything between NF and fi will beprinted verbatimso I'm going to put in a couple ofspaces here just to kind of Center it alittle bit and we'll say x uh as afunction of T is going to beX 0. now I'm going to make thatsubstrate subscript in a little bit andthat but that's okay I'm going to leavethe zero here for now plus v 0 t andagain I'll make that 0 on the v as asubscription a little bit but for rightnow we'll leave it as a placeholder plusand I'm going to put a fraction in hereand uh I'm going to I'll put the onehalf I have to draw that on my own andto keep I would normally put like ahyphen or something to kind of indicatethis is a fraction one over two but Idon't want to look like a minus symbolso we'll use an underscoreand so there's our placeholder for theone-half fraction and then a and then uht squared and so I'm gonna make the nextline I'm going to make a subscript or asuperscript uh for that and so I don't Idon't need to put in the two right nownow let's uh down here on the next linelet's now do the subscripts let's put inthe placehold for the subscripts andthere's our zero and our oops and thenour zero and then we'll do filling backon now we'll stop editing there let'ssee by the wayand what line number are we on this is23 so 23 is the dot f i and so if I backup a little bit then let's print lines20 to 23 and we're going to number themjust to kind of see what's what and so21 is the uh the line that has myequation on it and line 20 is the onethat has the dot NF on it and so let'sdo let's do 21 we'll print that one outwithout any tabs or line numbers beingput in there so that's that's exactlyhow it appears and so 20 I'm going toappend to line 20 this will now gobetween 20 and 21.and now let's do the the one and thehalf oh I forgot to put in the two uhfor my fraction so we'll have to fixline 22 in a minute uh and so let's goahead and put in I just do spaces andput in the one and then there's the 2 tomake the squaredand then I'm done making that edit sowe'll do a period and let's go back to20 to the end of the file and we'llprint those outokay and so uh line 20 is the NF 21 isthe one and the twois the one with the equation on it and23 now is the uh the zeros so I want tochange line 23and so I'm going to go over here and putin the 0 and the zero and then there'smy twoand then let's print out line 22.and so let's go ahead and get rid ofthose zeros and so we can do this we cansay starting at line 22 but then alsoending in line 22 we're going to swapany zeros with a spaceand let's do a global and so that shouldbe what I've just I think I just did theright thing so we'll print out the therest of the lines here 20 to the end ofthe of the file print those out and yepthat did what I needed to do so it I'venow created a formula that that lookslike the equation of motion X is afunction of time x is 0 plus v 0 t plusone half a t squared since I don't havethe eqn program to make equations for methis is the closest I can get on a plaintypewriter deviceuh by the way just to remind ourselveswhere we are here let's back up a littlebit so 15 to the end of the file we'llnumber those lines here and so then 24 Ican now start appending after 24 andthen I can sayumuh dot LP because this is just going tobe an assumption here let's do a fullparagraphumdropping an object uhwith uh[Music]zero initial velocityand uhassuming uh theuhwe measure the heightthe distancedropped after time and we'll do this asan italics time Twe can simplify the equation2 and then we'll just say here Dotwell let's finish editing here realquickumthe let me back up a little bit so 24until the end of the LA end of thethe file is that so I want to actuallyput inuh initial velocityuh so I'll do 26 append and I'll put anitalicsuh v0there all right so uh let's do the uhshould be now 31 should now be the lastline we'll do 30 comma the end of thefile we'll number those out and yep sowe can now simplify that so 31 appendwe're going to then do awhere is my equation how long how far indid I did I do my equation so we'll do20 to the end of the file we'll printthose out and then it was uhuh there we go so 31 append okay that'llbe the last lineI can now saylooks like it'sI did five so x tuh is going to beuh just one half 80 squared so there'sour bar for the one half there's our athere's our T and then we can put in theuh thethe two and then we need to turn fillingback onand thenI didn't track where I was supposed tobe so 28 29 30 31 so 31 append I want toturn filling off so no filland then I can also now insert the oneand that's the oneand then let's go ahead and print wherewe were again so 30 to the end of thefile of it numbered and thenand I can say 36 append uhlet's we can uhto measurea Timerequired to drop a distancewith an italics Xumcan be calculatedasand then we'll doanother one where it's no filland then we'll just sayfive it's going to be tequals the square rootofit's going to be 2x over a if we do thatmath right so that was uh we need tohave adivision there we want to put the the 2xthe a in there so there's our squareroot and then we'll up here we'll do theaon the bottom and then we'll turnfilling back on ending our editand so if I do a 36 to the end of theline print it outthen if that's 36 37 38 39 40 41 if I doa 41 append I can now put the 2x on topall right and so I think you can kind ofsee where this is going so it's it'skind of an interesting little file andjust write it back to the disk and if Idoquit that and then I can view that filewith more uh of uh about dot meyou can see I've got my title page upthere my header my footer I've centeredin the title I created a new page andthen I have the double spaced and then Ihave a section heading and then someparagraphs and so the paragraphs alsohave some equations in them which I'mjust double checking look correct andthen I haven't messed anything up and sothat looks okay to meand so now if I were torun n Roth on that nroth with me macrosand the the file was about.meand then I can run that into more justso I can look at it one screen at a timeand so that the first page was blankbecause that was the three inches thatit was trying to go down so there's mytitle and then the rest of the blankpage for page one and then we should beon page two over here and there we aredouble spaced and it looks like I needto single space on my uh on my myequations we can fix thatand but you can see otherwise the restof it is lookinglooking pretty good actually let's justgo ahead and take out the uh there's myfooter now let's go ahead and just takeout maybe thethat line spacing so we'll do add onabout.meand it was somewhere towards the top soit was something like let's start atfive and we'll go down to 15 and we'llnumber those lines and so there it islooks like 12 will need to get rid of sowe're going to say 12d and that'lldelete line 12 and so if I go back to uhI forgot to turn my prompt back on soI'm just typing into the into the airand then we'll start it at line 10 whichshould be the date instruction we'll godown to line 14 which should be the thispaper discusses and we'll print thoseout I'll do numberright and so now I've got I just verifythat I got rid of of what used to beline 12 which was the line spacing oftwo so I can write that back to disk andnow I've created a a Fortran program andI've now written a document about it uhlet's when we actually process thisuh this enrock file it'd be nice toactually verify what our uh line numbersare you know right so we don't actuallyhave a program to do that I wouldnormally write an AUX script to do thatit's very easy to do an awk just to putline numbers before each one or thesedays the cat command has that option uhbut in Unix 3rd Edition we didn't havethe ability with either of thoseprograms uh OCT didn't exist and Catdidn't have that option so let's write asimple C program that will put linenumbers in front of each line so we'llclear the screen here and we're going todo Ed on a program called lineum.comthis file doesn't exist this will be anew file let's go ahead and start a newone now uh I'm not going to be able towrite old original C on here so we'lljust do the best here that we can uh theuh so we're going to insert uh uh we'restarting here with by saying includestandard io.h and then I'll need to havea program in here int Main and then thatwill take two options so read thecommand line so into Arcand then care ARG Vand then I need to be able to processthe command line so I need to do ins Iand then I need to open some files andsold to a file of P filethat's our pointer to a file so what Ido here is I'm going to scan the commandlineand if if no files thenread fromstandard in and print to stand it outotherwiseopen each fileprocess themand so we're going to write a function alittle bit that will actually allow usto process these but for right now let'sgo ahead and check how many options wehave in our command line so we're doingif ARG C is equal to one that means thatwe only have the ARG V 0 which is thename of the program itself that means wedon't have any options on the commandline so we'll just say okay if that'sthe case then we'll call the thefunction line numfind them from using standard in as theinput and standard out is the outputand then we can be done with thatotherwise we'll just say else uh we'regoing to do a for Loop of I equals oneand then as long as I is less than theARG countthen we're going to increment I aftereach iteration of the loopand now we're going to open the file sowe're going to save the pointer to thefile using F open and ARG v i oops Iand we're going to read that fileand then if we so we'll say if the Ppointed to the file is no that means wecouldn't open itand so I'm going to do F printf to oopsto standard error and say cannot openfileand then we'll just name the fileso argbotherwiseotherwise now we've got an active filepointer it's correct and so I should beable to call line num my function that Ihave written yet using reading from Pfile and then printing the standard outand once I've done that I shouldprobably close I've closed the pointerto the file and that allows me to go onto the nextentry in the file right and the commandline and so that should be the end of myfor Loopandthat should also be the end of my elseblock and then the program can happilyreturn back the operating system sowe'll say return zeroall right so let's save that before weget lost now I need to write a functionthat will do line num and let's let'sput that before our main function solet's just look at what we've got hereone through five we'll number thoselines so I want to insert after line oneuh we'll do appendand so I'm going to put in a blank lineand then we'll write our function so thefunction is a void function doesn'treturn anything and we call it line numand we have a file input and a fileoutputand how do I need to read this I need tobe able to read thisas uh I need to be able to read it thereare different ways I could write thisthis function I could I could actuallydo it a very efficient way uh in termsof file i o where I'm I'm just readingin things to a bufferum I could do it another way I guess sowhere I could read it line at a time uhhere I'm going to do the very simplenaive way uh just because I'm I'm notdoing an algorithm video here this isjust a video to demonstrate how to useuh old uh Unix and so uh Ed is reallythe The Shining Point here so let's justdo a very simple function that readscharacters one at a time from the fileand then after every uh new line itprints uh a line number on the next lineso that will tell us uh which line we'reon and after every 66 lines because nRoth shouldgenerate 66 lines at a time because ifyou watch the other video you know thatuh you know nroth generates 66 linesbecause a printed page was 80 columnswide by 66 lines tall after every 66we'll have to reset the number back tooneso we need to have room for a characterthat we're going to read in and we'regoing to do a line number we'll justcall it line which we can initialize tooneall right so I guess we should probablystartuh by doing a printfon uh well spaces went out to two of theline number and then we'll do a colonand then we'll immediately print out therest of the line so that's the line andwe'll increment that after we're doneprinting itand then I think I can go ahead and loopthe uh the uh the uh the file now sowe'll do a doumand uh what we'll do is then I'll readCH using F get Cuh from the inputnow what that will do is that willreturn a character unless it's the endof the file in which case we'll returneof so we need to double checkif the the character is not eof now wecan actually do something with itand so what we're going to do is we'regoing to we should print it out firstbecause if it's a new line we'll want toprint after that so we'll do F put C andthat should be the character we want toput out and then where it is going to goand then we'll ask ifthe character is a new linethen we're on it we're on a new line sowe should print out the new line numberand so we'll just repeat we have upabove so printfand then percent to D and then line plusplusand that is thatand we'll do the 66 back to one in alittle bit just want to make sure thisworks and then that should be that andthen I have my do Loop which I'm endingas while CH is not the end of fileand that should be it and so I can nowsave thatand I should be able to just write thatback to disk let's let's compile thatlet's check it uh so let's do a uhCCof uh save the output of line num ofline num.cand that looks rightand so if I were to actually process[Music]we're going to do an N Roth using memacrosof uh about dot meand then put that into line numand then view that through morethen there's my line numbersandthey didn't set it so that it wouldre-set it back to 1 after 66 so 67 isactually the first line of page twoand there we are so now we're up to 100and so that should that looks like it'sworking so I'm going to quit that andnow if I uh go back into the line numprogramlet's go in and find that that Loop andso uh where it was it was sort oftowards the it was in that function soit was somewhere after line 10 and we'llgo up to lineuh go up to line 30.and we'll uh we'll print those lines outokay so there it is the uh so I'm goingto say uh let's do line 15 to line 20and we'll number those outand so that looks right and so after Iprint it outumLet's uh let's let's Nest itinside so we're going to do an 18 appendlet's do 18 print so I can see where itisbecause I want to make sure my indentingis right so we're going to do 18 we'regoing to pend after thatand I'm going to put in a blank line andthen we'll sayif now that we're done incrementing linetwo by one does it happen in line 18. ifline is greater than 66 thenline should get reset back to oneand that should be the edit so periodwill stop my append we'll write thatback to disk we'll end it and we'll dothe compile of sending it to the outputof line num of line num.c and that looksright so now I can do n Roth with the memacros of about.me I will pass thatthrough line num which is in the currentdirectoryand then we'll pass it into more so wecan see the outputand so there's my blank lines on the topthere's my title page which is threeinches downand then there's the rest of page oneand you can see that now on page two itstarts with line number onethere's my page header now I didn't douh you know page offset to create a leftand right margin that's easy enough todo but you since I've gone back to linespacing one you can see that myequations are showing up right so that'sgoodandit should be all the way down to 66lines for page two before it is now donewith uh with the file because nowremember it ended with every time ithits a new line it now uh prints in lineto run the next line we can go back andfix that if we wanted to if we reallywant to get rid of that trailing onecolon I don't really feel strong enoughto do that so we're not going to do thatbut what we just done here is we've nowcreateduh a Fortran programand we wrote a document about it usingthe about dot me using the the me macrosand enroth and we wrote A C program avery simple C program just to put someline numbers on there so you can see theoutput and so that is you know a typicaluse of how you would use uh Unix 50years ago and we use the add editorthroughout using these very simplecommands so what did you think of thisvideo you'd like to see other videoslike that let me know in the commentsbelow visit our website at freedos.orgjoin us on Facebook follow us onMastodon and consider supporting me onpatreonthank you