[[quoteright:350:[[WebAnimation/HomestarRunner http://static.tvtropes.org/pmwiki/pub/images/flask.jpg]]]]
[[caption-width-right:350:"And there's no precious graphics to help, either."]]

->''"Dammit! So let's recap: there are four directions that I can move in and none of them work. What the fuck am I supposed to do?"''
-->-- '''[[http://www.sydlexia.com/mysteryhouse.htm SydLexia]]''', reviewing ''[[http://en.wikipedia.org/wiki/Mystery_House Mystery House]]''

An annoying aspect of old-school TextParser-based {{Adventure Game}}s, especially InteractiveFiction, was a limited ability to recognize command inputs. These games would frequently not only refuse to do what you wanted them to do, but also not give you any hint as to what you were ''supposed'' to do. For example, let's say the command to look at a monster was "look monster". If you typed in "look at monster", the game might say something like, "I don't know how to do that" or "I don't see an 'at' here". It was enough to make you
want to [[ComputerEqualsMonitor put your fist through the screen]].

The TropeNamer is ''WebAnimation/HomestarRunner'', specifically the ''WebAnimation/StrongBadEmail'' "[[http://www.homestarrunner.com/sbemail94.html video games]]", where Strong Bad imagines himself as a character in a text-based adventure game and envisions this problem occurring:

-->'''Strong Bad:''' And you'd be all like, "get ye flask", and it'd say "[[YeOldeButcheredeEnglishe You can't get ye flask]]", and you'd just have to sit there and imagine ''why on Earth'' you can't get ye flask! Because the game's certainly not going to tell you.

This phenomenon, alternatively known as "Guess the Verb" or "Guess the Syntax", is a defining trope of InteractiveFiction; although parsers have improved over time, the problem has never gone away completely, and probably won't for as long as developers amuse themselves with text parsers that [[DevelopersForesight try to predict a player's off-the-wall inputs]] and create suitably off-the-wall responses. Fans of the genre insist the problem was never as bad as people claim and [[NeverLiveItDown lament it being the genre's defining characteristic]], but it remains a sign of shoddy programming.

Different games have developed different ways to avoid the problem over time. Some games will tell you up-front all of the verbs and nouns it will accept; Chris Crawford's ''Storytron'' engine gives you a drop-down list for each part of the sentence which will only offer you valid combinations. Another way is to anticipate archaic or unusual synonyms for certain words (''e.g.'' calling a bathtub plug a "stopper"); some games even allowed you to define a word in terms of the game's established vocabulary, effectively giving you a custom command.

Some companies had better parsers than others; Creator/{{Infocom}} and Creator/{{Legend|Entertainment}} tended to have good, responsive parsers, whereas Creator/{{Sierra}} games were infamous for this problem.

Compare PixelHunt, the equivalent trope for PointAndClick games. Contrast DevelopersForesight and UnexpectedlyRealisticGameplay, which in text-based games generally means that even commands you ''wouldn't'' expect to work will do something. Has nothing to do with YouCannotGraspTheTrueForm.


* ''VideoGame/Deathmaze5000'', for the UsefulNotes/TRS80 and UsefulNotes/AppleII, contained ([[http://www.platypuscomix.net/applepalooza/deathmaze.html among other things]]) several problems of this type:
** In the first level, there's a pit containing an item you need to complete the game. Once you stepped on it, you were stuck in one place, and your only clue was "[[Literature/TheBible To everything there is a season]]," and, to hammer the point home, after a few minutes it would also shout, "To everything, [[Music/TheByrds TURN TURN TURN]]." Typing in "Turn" did nothing. Physically turning using the move keys did nothing. None of the items on that level were "turnable". The only way to know what to do was to [[GuideDangIt buy the hint sheet from the software company]].
** At another point in the game, you had to fart to get out of trouble. You had to guess that you had to type "fart" to do this. There were no hints that this was a valid command, and even if you used it before, there was no indication that it did anything useful (although it did propel you down the hallway [[FartsOnFire on a jet of your own exhaust]]).
* 8-bit adventure ''VideoGame/HeroesOfKarn'' required you to extinguish some smouldering ashes with the water you were carrying. None of [[AC:PUT WATER ON, DROP WATER ON, POUR WATER ON, USE WATER WITH, QUENCH, DOUSE, EXTINGUISH, COOL, DAMPEN, MOISTEN, SOAK, DRENCH, FLOOD, WET]] or [[AC:IMMERSE ASHES]] would work. It would only accept "[[AC:WATER ASHES]]". Figuring this out was by far the hardest part of the game.
* Parodied in ''VideoGame/HugosHouseOfHorrors'':
-->-> open bolt
-->Please say "undo bolt".
* ''VideoGame/LauraBow'' had issues with the generic "{{use|Item}}" command, which adventure gamers had been conditioned to use as a catch-all verb to use an item. Here, you had to guess the correct verb; typing "Use crank", for instance, would give you "How do you want to use the crank, Laura?"
* Pretty much the entire point of ''VideoGame/PickUpThePhoneBoothAndAisle'' is trying different verbs to see what ending you get.
* Creator/{{Sierra}} was infamous for this sort of problem, as its parser never evolved beyond simple "<verb> <noun>" phrases, even after a decade:
** Sierra's very first game, ''VideoGame/MysteryHouse'', infamously accepted "[[AC:PRESS BUTTON]]" but not "[[AC:PUSH BUTTON]]".
** ''VideoGame/LeisureSuitLarry 2'' had an infamous sequence at the end where the player has to make a bomb using an airsick bag as the wick. The problem is that "bag" is not considered a synonym for "airsick bag", despite there being no other bag in a five-mile radius. Lead programmer Al Lowe [[http://www.allowe.com/Larry/cluescheats.htm#Larry2 explained]] that this was the result of an unrelated bug which another programmer fixed by turning "bag" into a verb, which Lowe never noticed and escaped all testing. [[UrbanLegendOfZelda Longtime scuttlebutt]] suggested that the correct command was a full but grammatically incorrect sentence with the word "the" repeated several times.
** ''VideoGame/KingsQuest'' games mostly allowed you to unlock doors with a variety of phrases, such as "open door with key", "put key in hole", or "use key to open door" -- but the magical door in ''VideoGame/KingsQuestIIRomancingTheThrone'' could only be opened with the command "unlock door".
** ''VideoGame/KingsQuestIIIToHeirIsHuman'':
*** As part of its copy protection, the game included several spells the player needed to cast. Rather than an easily-copied phrase, each spell consisted of several steps requiring advance preparation. Unfortunately, several of those steps required a specific verb or the entire process would fail.
*** A key item is located on top of a wardrobe. Unfortunately, while "look on wardrobe" is accepted, it only gives the player a description of the wardrobe itself. This can cause the player to then walk off assuming that they have already tried looking on top of the wardrobe. "Look ''above'' wardrobe" is the command actually needed.
** In the first ''VideoGame/SpaceQuest'' game, you have to "insert" the keycard. No synonym or rephrasing of that unusual and unnecessarily technical term will be accepted.
** Parodied at one point in ''VideoGame/QuestForGloryII'', where the player has to use a lamp to catch a fire elemental. While "[[UseItem Use lamp]]" is the "correct" input, the game will not only accept synonyms but even has funny messages tied to them; "put down lamp" has the player verbally abuse the lamp, while "drop lamp" has the player break up with it.
*** Likewise, later in the game the player has to steal a "[[Film/TheMalteseFalcon Blackbird statue]]" for a local thief. When he asks you to hand it over, the command "give Ferrari the bird" not only works but produces [[FlippingTheBird the expected result]].
* Among the many frustrating puzzles in ''VideoGame/StarshipTitanic'' is obtaining a broken eye from Titania, the ship's AI. It's one of four similar looking globes (the others are light bulbs). You can poke it, and the game will tell you what it is. But you can't just grab it yourself; you have to summon the Bellbot, hold your cursor over the correct globe, and type, "Get the broken eye". "Get the eye", "Hand me the eye", "Give me Titania's eye", and "Give the eye to me" will not work; bizarrely, "Get the broken bulb" will.
* A Spanish-language video game adaptation of ''ComicBook/ZipiYZape'' had a sequence where you had to [[ThumbtackOnTheChair drop a nail on the ground]] so that your father sits on it [[ItMakesSenseInContext and drops a patch]]. It took players ''seventeen years'' to find the correct command, "throw nail under tree" -- and that only through hacking the game files. People had been trying all sorts of variations of "drop nail" or "put nail near father", with no success. More detail in Spanish [[http://lineadura.wordpress.com/2006/03/01/derribando-el-mito-%c2%bfquien-mato-a-la-aventura-conversacional here]].
* ''VideoGame/HeroinesQuest'' references the TropeNamer; if you try to take certain flasks from the herbalist's shop, it will straight-up tell you that "you can't get ye flask".

* Creator/ScottAdams' 1978 ''VideoGame/{{Adventureland}}'' required the player to enter the unintuitive [[AC:UNLIGHT LAMP]] in order to prevent a lamp from using up its fuel; it would not recognize the verb [[AC:EXTINGUISH]] (and certainly not the phrases [[AC:PUT OUT]] or [[AC:TURN OFF]]).
* WebVideo/TheAngryVideoGameNerd encountered this problem trying to play ''The Count'' on the UsefulNotes/VIC20, resulting in this exchange where he can't even find his way out of a room:
-->"Okay, so I went north? What'd that do?"\\
[[AC:> go east]]\\
[[AC:OK. What shall I do now?]]\\
[[AC:> go east again]]\\
[[AC:Use 1 or 2 words only!]]\\
"Oh, okay, I'll give you two words!"\\
[[AC:> fuck you]]\\
[[AC:Don't know how to "FUCK" something.]]
* ''VideoGame/{{Bureaucracy}}'' uses this as a game mechanic; you get penalized for inputting an incorrect command, by an increase in "blood pressure". If blood pressure becomes dangerously high, your character dies.
* ''VideoGame/{{Curses}}'' by Graham Nelson had a section where you had to cram a voice-operated robot mouse into a mouse hole and then give it instructions -- only the standard commanding language explained in the instructions ("mouse, go north") didn't work. Trying every verb on every object randomly might bring you to the correct solution: you have to address the hole, not the mouse ("hole, go north").
* The ''Literature/{{Fahrenheit 451}}'' text adventure, already [[NintendoHard fiendishly difficult]], exacerbated the problem with parser issues. Sometimes different commands worked in different situations; you might need "talk to man" in one instance, but "ask man" in another, and there was no indication of which one to use. Worse, you advanced the plot by contacting members of [[LaResistance the Underground]], using literary quotations as pass-phrases -- but if you typed them in incorrectly, even the punctuation, the game would boot you out of the building and force you to make your way all the way back inside.
* ''Guess the Verb'' is an InteractiveFiction game that satirizes the concept; each scenario can only be resolved by guessing an uncommon verb.
* The text adventure adaptation of ''VideoGame/TheHitchhikersGuideToTheGalaxy'' seemed to use bad parsing and senseless commands almost deliberately; one PC magazine described the game as "toying with various ways of saying [[AC:PUT BABEL FISH UP ZAPHOD'S JACKSIE]]." Specifically:
** An early puzzle on the Vogon ship required you to remember a particular word from the Vogon poetry and type it in while you were in the airlock. But you need to include quotation marks -- and [[UnwinnableByMistake not all ports of the game supported them]].
** At one point in the game, you're ''expected'' to type in an invalid command; it's designed to spontaneously enter a wormhole, be interpreted as [[InMyLanguageThatSoundsLike a grave insult]], and instigate a bloody war between two alien races, but you couldn't have guessed that. If you could, though, you do get extra kudos for inputting the actual line from [[Literature/TheHitchhikersGuideToTheGalaxy the book]] that serves this purpose: [[spoiler:"I seem to be having tremendous difficulty with my lifestyle"]].
** You have to obtain a cup of tea, but the game will reject the command [[AC:GET TEA]]. That's because it's ''not'' actually tea, but rather an "Advanced Tea Substitute" (or "ATS" -- almost, but not quite, entirely unlike tea). You had to type [[AC:GET CUP]] or [[AC:GET ATS]]. It's important to know this distinction because later in the game, [[spoiler:you obtain real tea, and you have to demonstrate your philosophical depth by carrying tea and no tea at the same time]].
* The ''[[VideoGame/TheSpellcastingSeries Spellcasting 101]]'' series tried to avert this trope by showing a complete list of all the verbs the game would accept in a sidebar; you could play the entire game with just a mouse.
* Infocom's text adventure adaptation of James Clavell's ''Literature/{{Shogun}}'' has the protagonist trying to communicate with the Japanese by searching or a common language. Some players tried inputs in actual foreign languages, which wouldn't work. But if you typed something like "Say 'where am I' in Spanish", you'd crash the parser.
* ''Murder in the Museum'' on the ''Big Blue Disk'' deliberately and cruelly {{invoked|trope}} this trope and forced the player to guess obscure nouns -- ''e.g.'' you must type "femur" for what was described as a "leg bone" or "Derringer" for what was described as "small gun". It also gave you a time limit, which limited the number of guesses you could make.
* The original ''ADVENT'', ''a.k.a.'' ''VideoGame/ColossalCave'', had a sequence that looked like a [[DevelopersForesight snappy comeback to a stupid input]], but was actually required to progress, as it was the only way to kill the dragon:
--> [[AC:> kill dragon]]\\
With what? Your bare hands?\\
[[AC:> [[BluntYes yes]]]]\\
Congratulations, you have [[ViolationOfCommonSense killed the dragon with your bare hands!]] (Unbelievable, isn't it?)
* The EdutainmentGame ''VideoGame/VoicesOfSpoonRiver'' several times explicitly tells the player to "place" something on something else -- but the verb "place" isn't implemented. It's not too hard to figure out that you have to "put" instead, but it's still weird.
* ''VideoGame/AdVerbum'' makes an art of this -- for instance, one room is described entirely in words beginning with S, and will only accept commands beginning with S (of note: the only exit is to the north). On the plus side, the parser is willing to accept a large number of words that wouldn't appear in a normal game.
* In ''VideoGame/TheSixFootTallManEatingChicken'' asks you at one point to plug a hole in a bucket with a cork. The words "plug" and "use" don't work; you have to [[spoiler:write "put", which is not otherwise used]].
* Infocom's ''VideoGame/{{Enchanter}}'' at one point places an essential scroll (essential as in "the game cannot be successfully completed without it") inside a mouse hole. Retrieving the scroll is complicated in that "get scroll" doesn't work, and neither does "get all from hole," or any permutation thereof. The only command that will work is "reach into hole," which wouldn't have been so aggravating if "reach" was used anywhere else in the game.
* This sort of problem, among others, is heavily parodied in the Adrift games featuring Clueless Bob Newbie, text adventure "author" and legend in his own mind.
* Apple II adventure game ''[[http://en.wikipedia.org/wiki/The_Mask_of_the_Sun Mask of the Sun]]'' featured a battle against a skeleton which could only be defeated by using a magic amulet picked up earlier in the game. Unfortunately, the only phrase which would allow you to successfully battle the skeleton was the non-intuitive "[[AC:FIGHT AMULET]]". Computer game developer Dan Spitzley described the anguish this generated within his family on IGN's [[https://web.archive.org/web/20051230085426/http://rpgvaultarchive.ign.com/archive/19990822.shtml RPG Vault]] in 1999.
* One puzzle in the UsefulNotes/ZXSpectrum game ''Danger! Adventurer at Work!'' is to [[Franchise/{{Frankenstein}} animate a monster using electricity]]. The only commands which will do this are "[[AC:ATTACH ELECTRODES]]" followed by "[[AC:THROW SWITCH]]". Reasonable alternatives such as "[[AC:CONNECT WIRES]]" or "[[AC:TURN ON POWER]]" don't work.

* Parodied in the screenshots of [[http://paragonwiki.com/wiki/April_Fools%27_Day#2009 this]] ''VideoGame/CityOfHeroes'' AprilFoolsDay announcement, which illustrates a text-based version of the game.
* ''VideoGame/{{Everquest}}'' suffers from a form of this trope. When talking to {{NPC}}s, you will find certain words in [brackets], indicating that they have more to say on that subject; you need to type those words into the chat log to continue down that line of conversation. But it's not always as simple as just repeating the words; sometimes, you have to put it in the form of a question, and just as often you just added the word "what" before the bracketed text without regard for syntax. Other times, [[TrollingCreator the developers are clearly messing with you]], like when you ask Bootstrutter about "jboots" only for him to say, "What nonsense is this about jboots? Speak to me of Journeyman's Boots!"
* In one storyline mission in ''VideoGame/ForumWarz'', you have to complete a text adventure game and tell the character who gave you the mission how you did it. In the mission ending conversation, you tell him you have to enter the command "push button", not "press button". But while playing the text adventure itself, you can complete that section with the command "use button".
* The Leaflet Quest section of ''VideoGame/KingdomOfLoathing'' that is a ShoutOut to the ''VideoGame/{{Zork}}'' games. Since it's not too large, a ''lot'' of detail was put into putting smart-aleck responses to random commands not facilitated by the usual Creator/{{Infocom}} queue. But it also had its Ye Flask moments; typing "enter house" makes you go inside the house, but "leave house" and "exit house" won't work; you have to "(go) west" to get back outside. This is especially confusing for text-quest newbies, as the house is right next to the starting point and they may not even realize that "go [direction]" commands exist.
* To this day, LPMUD still can't parse ''look <object>'' without admonishing the player to "Look AT or IN something." Even some DikuMUDS still hold to this convention. Even though ''examine <object>'' can be abbreviated to ''x <object>'', ''look'' won't be accepted without a preposition. Creator/{{Infocom}} and Creator/{{Legend|entertainment}} games likewise do not accept "look <object>" or "use <object>" on grounds that they aren't meaningful sentences.

[[AC: RolePlayingGames]]
* Oddly enough, this was a reason the answer puzzles were so reviled in ''VideoGame/TalesOfRebirth'', despite coming out in 2004 when such problems should have been long fixed. Instead of having a list of choices to input, one had to write out their answer to the puzzle -- and it was very fussy about the specific wordings it would accept, taking almost no synonyms. No other ''VideoGame/TalesSeries'' game uses this system, instead offering several dialogue options. Several of these puzzles were dropped in the remake, and this may have contributed to the game [[NoExportForYou not being translated]].
* ''VideoGame/{{Elona}}'' occasionally lets you [[MakeAWish type in an item's name and have it granted to you]]. However, the text parser is wonky and sometimes grants you something different from what you wanted.

* ''[[VideoGame/OperatorsSide LifeLine]]'' on the [=PS2=] plays similarly to a text adventure, albeit one controlled by the player's voice than with a keyboard. Aside from the [[FakeDifficulty joys of iffy voice recognition]] causing much frustration and the genre standard "Guess the Noun" portions, there are several instances in which very specific phrases must be used to get the proper effect. [[CollectionSidequest One chip]] is particularly difficult to acquire, just because it was located behind a bag of some sort, and telling Rio to "check behind bag" didn't work for some reason.

!!Non-video game examples:

* WebVideo/{{Phelous}} points out that the website in ''Film/FearDotCom'' seems to run on this sort of interface.
* ''Film/IRobot'' shows Detective Spooner speaking with Dr. Lanning's hologram several times, and is frequently frustrated at the rather shallow pool of questions that it has been programmed to answer.

[[AC: LiveActionTV]]
* Parodied in [[https://www.youtube.com/watch?v=TancpHm4f4A an episode]] of the ''Series/LimmysShow'' sketch "Adventure Call" (part adventure game, part premium-rate phone-in game show), when a contestant encounters a troll. He attempts both "Get troll" and "Put troll in {{bag|OfHolding}}" to no avail, before attempting "Get troll" again, learning that Falconhoof doesn't understand how to "get" the troll. But then...
-->'''Caller:''' What is a troll?\\
'''Falconhoof:''' A troll is a creature. Remember, you have a spear!\\
'''Caller:''' Get creature.\\
'''Falconhoof:''' ''({{beat}})'' [[ScrewThisImOuttaHere Game over. Game over, you have been killed!]]

[[AC: TabletopGames]]
* This can occasionally happen in TabletopGames, even though there's a real person at the other end who can presumably understand you. It usually happens when the PC and the GM have completely different ideas about what the player is trying to do. This can lead to hysterical and/or catastrophic results.

* ''WebAnimation/HomestarRunner'' is the TropeNamer, and that reference (seen in the trope description) has become [[MemeticMutation so famous]] that it's become a RunningGag in ''Homestar Runner'' media -- especially its video games. For instance:
** In ''VideoGame/ThyDungeonman'', you have to guess the correct command [[LoadBearingBoss as the dungeon caves in on you]].
** In ''Thy Dungeonman 2'', the game explicitly tells you in certain rooms that cardinal directions like "east" and "west" won't work, and instead you have to use commands like "eastward" and "roughly westish".
** Several games explicitly reference "ye flask"; ''Thy Dungeonman 3'' makes getting ye flask the object of the game, and ''VideoGame/StrongBadsCoolGameForAttractivePeople'' has an extended rant about leaving "ye flasks" around without letting others get them. We even get to see Strong Bad struggling mightily and failing to reach it onscreen, just to make it even more ridiculous when we can plainly see he shouldn't have trouble getting it.

* ''Webcomic/DinosaurComics'' references the phenomenon, along with other early AdventureGame tropes, especially their tendency to be NintendoHard. [[http://www.qwantz.com/index.php?comic=778 One strip]] sees T-Rex wondering what life would be like as a text-based adventure; Utahraptor points out that no one would ever be able to get out of bed until they found the right command:
-->[[AC:> get up]]\\
[[AC:I don't see "up" here]]
* At one point, the cast of ''Webcomic/OkashinaOkashi'' gets trapped in an alternate dimension based on these games. It was a dark void where the girls had to shout out commands based on the old text adventure games. This led to jokes about bad parsing, shouting "''Why'' can't I get ye flask!", and crying.
%% * Taken UpToEleven with ''Webcomic/ProblemSleuth'' and ''Webcomic/{{Homestuck}}''.
%% ** [[Webcomic/{{Jailbreak}} What]] [[RunningGag pumpkin?]]
%% ** However, you can get ye flask. In a published edition, WordOfGod says that he didn't know the reference at the time.
%% * [[http://www.thenoobcomic.com/index.php?pos=199 This]] page of Webcomic/TheNoob. [[Apparently not, because the linked comic doesn't appear to reference the trope]].
* [[{{Pun}} uni.xkcd.com]] ([[http://uni.xkcd.com/ viewable here]]), a UNIX interface based on ''Webcomic/{{XKCD}}'', is all about this sort of thing:
-->$ where am i
-->Unrecognized command. Type "help" for assistance.
-->$ help
-->That would be cheating!
** Command Spoiler [[https://github.com/chromakode/xkcdfools/wiki/commands here]], or [[https://github.com/chromakode/xkcdfools/blob/master/src/xkcd_cli.js in the source]]
* During a 'dream-sequence' in ''Webcomic/{{SSDD}}'', Tess finds herself beset by a text-parser and - with her habitual lack of patience for AI's - quickly pissed off by it. This eventually results in a strip which is actually a fully-functional text-adventure, complete with low-def images in brilliant TANDY colors. Playable [[http://poisonedminds.com/d/20170429.html here]].

[[AC: WebOriginal]]
* The ''Website/{{Cracked}}'' page "[[http://www.cracked.com/blog/revisiting-old-school-text-adventures-as-a-jaded-modern-gamer/ Revisiting Old School Text Adventures as a Jaded Modern Gamer]]" describes the AI reacting with shocked horror to the insane player's sadistic commands and eventually feeding him to a swarm of monsters out of spite.
* ''Wiki/SCPFoundation'': [[http://www.scp-wiki.net/scp-603 SCP-603-44]] is an InteractiveFiction game in which almost all commands players have tried to input have resulted in messages saying that there is no such object here or that "you cannot [do X]." "Die" is the only command known to have an effect, and it affects the actual player.
* Parodied in ''WebAnimation/ZeroPunctuation's'' review of ''VideoGame/SuperMarioGalaxy2'':
-->'''[[AC:You are a greasy Italian spaz standing on a platform unsupported in the middle of the yawning void of space.]]'''
-->'''[[AC:What Now?]]'''
-->'''[[AC:[[BatmanCanBreatheInSpace You can't do that [somehow].]]]]'''
* In the ''LetsPlay/MarioPartyTV'' series, after several incidents where correctly guessing a certain fruit during Mic Mini-games was treated as a mistake, the guys realized that they were saying ''grape'', not ''grapes''.
* Parodied in the famous "[[http://www.oldmanmurray.com/features/77.html Death of Adventure Games]]" article of Website/OldManMurray.
-->'''[[AC:You are on a pirate ship!]]'''
-->[[AC:> Go north!]]
-->'''[[AC:You can't go north!]]'''
-->[[AC:> Examine ship!]]
-->'''[[AC:I don't see a ship here!]]'''

[[AC: RealLife]]
* Many text parsers are modelled off UNIX command lines. UsefulNotes/{{UNIX}} in general is precise, arbitrary, and ''case-sensitive''. "/Home" would be interpreted as a different directory than "/home". It doubles as a DamnYouMuscleMemory if you're used to another command-line interface like DOS (used in Windows Command Prompt) -- all command lines have a tendency to do this (which is why they're not used so much today). Fortunately, the command ''man [command]'' will print an extensive [[AllThereInTheManual manual page]] for whatever command "[command]" is; unfortunately, you basically have to be fluent in Linux jargon anyway to decipher half of it. Among the parser issues:
** A simple arithmetic operation like "2+2" will, in many shells, result in "Command Not Found". You have to type ''echo $((2+2))''. And shell scripts are considered one of the easier programming languages.
** UNIX doesn't quite know how to cope with spaces in filenames, so you can't save a file as "Some File.jpg". To fix the problem, you have to enter ''mv "Some File.jpg" Some_File.jpg'', essentially forcing UNIX to read the filename as a single string.
** The command to print the contents of a file to your terminal is not ''read file1'', ''print file1'', or even ''echo file1'', but '''''cat''' file1''. "cat" stands for "'''cat'''enate", a somewhat esoteric term referring to the program's ability for sequential linkage and printing to stdout of multiple files -- even though it's used much more often to print the contents of just a single file. Its touted sequential linkage functionality is useful for shell scripts, however.
** If you try to close a Python session by typing ''exit'', it will not work. However, the parser will understand what you wanted to do and helpfully inform you that you should type ''exit()'' instead. [[SarcasmMode Gee, thanks.]]
*** The parser actually still sees ''exit'' as a regular variable name, which just happens to be a function with a particularly unusual string representation.
* The UserNotes/XboxOne's voice recognition can feel like this sometimes, due to the unintuitive nature of some of the commands and the fact that a list of commands is not included with the console (though one can be found on the official Xbox support forums). For instance, if you want to start playing a game, you can't say, "Xbox, play [game]", or "Xbox, start [game]", or "Xbox, launch [game]"; you have to say "Xbox, ''go to'' [game]." And while you can say "Xbox on" to power the Xbox up, saying "Xbox off" doesn't turn it off; you have to say "Xbox, ''turn'' off."