Is it yaml or yml

Question

According to yaml org  the official file extension is  yaml    Quote       Is there an official extension for YAML files       Please use   yaml  when possible    However there seems to be a disagreement on the internet on which extension to use  If you look up examples on the web  many of them use the unsanctioned  yml extension    Searching Google returns nearly 3 times as many results for the shorter one      49 100     15 400    So which am I supposed to use  The proper 4 letter extension suggested by the creator  or the 3 letter extension found in the wild west of the internet

User · Answer

yaml is apparently the official extension  because some applications fail when using  yml  On the other hand I am not familiar with any applications which use YAML code  but fail with a  yaml extension    I just stumbled across this  as I was used to writing  yml in Ansible and Docker Compose  Out of habit I used  yml when writing Netplan files which failed silently  I finally figured out my mistake  The author of a popular Ansible Galaxy role for Netplan makes the same assumption in his code   - name  Capturing Existing Configurations   find      paths   etc netplan     patterns     yml   yaml    register   netplan configs   Yet any files with a  yml extension get ignored by Netplan in the same way as files with a  bak extension  As Netplan is very quiet  and gives no feedback whatsoever on success  even with netplan apply --debug  a config such as 01-netcfg yml will fail silently without any meaningful feedback

User · Answer

After reading a bunch of people s comments online about this  my first reaction was that this is basically one of those really unimportant debates   However  my initial interest was to find out the right format so I could be consistent with my file naming practice     Long story short  the creator of YAML are saying  yaml  but personally I keep doing  yml   That just makes more sense to me   So I went on the journey to find affirmation and soon enough  I realise that docker uses  yml everywhere   I ve been writing docker-compose yml files all this time  while you keep seeing in kubernetes  docs  kubectl apply -f   yaml     So  in conclusion  both formats are obviously accepted and if you are on the other end   ie  writing systems that receive a YAML file as input  you should allow for both   That seems like another snake case versus camel case thingy

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EDIT      So which am I supposed to use  The proper 4 letter extension suggested by the creator  or the 3 letter extension found in the wild west of the internet    This question could be    A request for advice  or A natural expression of that particular emotion which is experienced  while one is observing that some official recommendation is being disregarded   prominently  or even predominantly    People differ in their predilection for following    Official advice  or The preponderance of practice    Of course  I am unlikely to influence you  regarding which of these two paths you prefer to take   In what follows  and  in the spirit of science   I merely make an hypothesis  about what  merely as a matter of fact  led the majority of people to use the 3-letter extension  And  I focus on efficient causes   By this  I do not intend moral exhortation  As you may recall  the fact that something is  does not imply that it should be   Whatever your personal inclination  be it to follow one path or the other  I do not object    End of edit    The suggestion  that this preference  in real life usage  was caused by a 8 3 character DOS-ish limitation  IMO is a red herring  erroneous and misleading    As of August  2016  the Google search counts for YML and YAML were approximately 6 000 000 and 4 100 000  to two digits of precision   Furthermore  the  YAML  count was unfairly high because it included mention of the language by name  beyond its use as an extension   As of July  2018  the Google s search counts for YML and YAML were approximately 8 100 000 and 4 100 000  again  to two digits of precision   So  in the last two years  YML has essentially doubled in popularity  but YAML has stayed the same   Another cultural measure is websites which attempt to explain file extensions  For example  on the FilExt website  as of July  2018   the page for YAML results in   Ooops  The FILEXT com database does not have any information on file extension  YAML    Whereas  it has an entry for YML  which gives   YAML   uses a text file and organizes it into a format which is Human-readable   database yml  is a typical example when YAML is used by Ruby on Rails to connect to a database    As of November  2014  Wikipedia s article on extension YML still stated that   yml  is  the file extension for the YAML file format   emphasis added   Its YAML article lists both extensions  without expressing a preference   The extension   yml  is sufficiently clear  is more brief  thus easier to type and recognize   and is much more common   Of course  both of these extensions could be viewed as abbreviations of a long  possible extension    yamlaintmarkuplanguage   But programmers  and users  don t want to type all of that   Instead  we programmers  and users  want to type as little as possible  and still yet be unambiguous and clear  And we want to see what kind of file it is  as quickly as possible  without reading a longer word  Typing just how many characters accomplishes both of these goals  Isn t the answer three  3   In other words  YML   Wikipedia s Category Filename extensions page lists entries for  a   o and  Z  Somehow  it missed  c and  h  used by the C language   These example single-letter extensions help us to see that extensions should be as long as necessary  but no longer  to half-quote Albert Einstein    Instead  notice that  in general  few extensions start with  Y   Commonly  on the other hand  the letter X is used for a great variety of meanings including  cross    extensible    extreme    variable   etc   e g  in XML   So starting with  Y  already conveys much information  in terms of information theory   whereas starting with  X  does not   Linguistically speaking  therefore  the acronym  XML  has  in a way  only two informative letters   M  and  L     YML   instead  has three informative letters   M    L  and  Y    Indeed  the existing set of acronyms beginning with Y seems extremely small  By implication  this is why a four letter YAML file extension feels greatly overspecified   Perhaps this is why we see in practice that the  linguistic  pressure  in natural use  to lengthen the abbreviation in question to four  4  characters is weak  and the  linguistic  pressure to shorten this abbreviation to three  3  characters is strong   Purely as a result  probably  of these factors  and not as an official endorsement   I would note that the YAML org website s latest news item  from November  2011  is all about a project written in JavaScript  JS-YAML  which  itself  internally prefers to use the extension   yml    The above-mentioned factors may have been the main ones  nevertheless  all the factors  known or unknown  have resulted in the abbreviated  three  3  character extension becoming the one in predominant use for YAML   despite the inventors  preference     YML  seems to be the de facto standard  Yet the same inventors were perceptive and correct  about the world s need for a human-readable data language  And we should thank them for providing it

User · Answer

The nature and even existence of file extensions is platform-dependent  some obscure platforms don t even have them  remember  -- in other systems they re only conventional  UNIX and its ilk   while in still others they have definite semantics and in some cases specific limits on length or character content  Windows  etc     Since the maintainers have asked that you use   yaml   that s as close to an  official  ruling as you can get  but the habit of 8 3 is hard to get out of  and  appallingly  still occasionally relevant in 2013

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