Doing a cleanup action just before Node js exits

Question

I want to tell Node js to always do something just before it exits  for whatever reason     Ctrl C  an exception  or any other reason   I tried this   process on  exit   function         console log  Goodbye           I started the process  killed it  and nothing happened  I started it again  pressed Ctrl C  and still nothing happened

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Just wanted to mention death package here  https   github com jprichardson node-death  Example   var ON DEATH   require  death    uncaughtException  true      this is intentionally ugly  ON DEATH function signal  err        clean up code here

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This catches every exit event I can find that can be handled   Seems quite reliable and clean so far     exit    SIGINT    SIGUSR1    SIGUSR2    uncaughtException    SIGTERM   forEach  eventType    gt      process on eventType  cleanUpServer bind null  eventType

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In the case where the process was spawned by another node process  like   var child   spawn  gulp     watch          stdio   inherit         And you try to kill it later  via   child kill      This is how you handle the event  on the child    process on  SIGTERM   function         console log  Goodbye

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Here s a nice hack for windows  process on  exit   async      gt        require  fs   writeFileSync    tmp js    crash    utf-8

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async-exit-hook seems to be the most up-to-date solution for handling this problem  It s a forked re-written version of exit-hook that supports async code before exiting

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exit  is an event that gets triggered when node finish it s event loop internally  it s not triggered when you terminate the process externally   What you re looking for is executing something on a SIGINT   The docs at http   nodejs org api process html process signal events give an example   Example of listening for SIGINT      Start reading from stdin so we don t exit  process stdin resume     process on  SIGINT   function        console log  Got SIGINT   Press Control-D to exit           Note  this seems to interrupt the sigint and you would need to call process exit   when you finish with your code

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The script below allows having a single handler for all exit conditions  It uses an app specific callback function to perform custom cleanup code   cleanup js     Object to capture process exits and call app specific cleanup function  function noOp        exports Cleanup   function Cleanup callback          attach user callback to the process event emitter      if no callback  it will still exit gracefully on Ctrl-C   callback   callback    noOp    process on  cleanup  callback         do app specific cleaning before exiting   process on  exit   function          process emit  cleanup                catch ctrl c event and exit normally   process on  SIGINT   function          console log  Ctrl-C           process exit 2              catch uncaught exceptions  trace  then exit normally   process on  uncaughtException   function e        console log  Uncaught Exception           console log e stack       process exit 99              This code intercepts uncaught exceptions  Ctrl C and normal exit events  It then calls a single optional user cleanup callback function before exiting  handling all exit conditions with a single object   The module simply extends the process object instead of defining another event emitter  Without an app specific callback the cleanup defaults to a no op function  This was sufficient for my use where child processes were left running when exiting by Ctrl C   You can easily add other exit events such as SIGHUP as desired  Note  per NodeJS manual  SIGKILL cannot have a listener  The test code below demonstrates various ways of using cleanup js     test cleanup js on version 0 10 21     loads module and registers app specific cleanup callback    var cleanup   require    cleanup   Cleanup myCleanup     var cleanup   require    cleanup   Cleanup       will call noOp     defines app specific callback    function myCleanup       console log  App specific cleanup code              All of the following code is only needed for test demo     Prevents the program from closing instantly process stdin resume        Emits an uncaught exception when called because module does not exist function error       console log  error      var x   require             Try each of the following one at a time      Uncomment the next line to test exiting on an uncaught exception   setTimeout error 2000       Uncomment the next line to test exiting normally   setTimeout function   process exit 3    2000       Type Ctrl-C to test forced exit

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After playing around with other answer  here is my solution for this task  Implementing this way helps me centralize cleanup in one place  preventing double handling the cleanup    I would like to route all other exiting codes to  exit  code    const others     SIGINT    SIGUSR1    SIGUSR2    uncaughtException    SIGTERM   others forEach  eventType    gt        process on eventType  exitRouter bind null    exit  true            What the exitRouter does is calling process exit     function exitRouter options  exitCode       if  exitCode    exitCode     0  console log  ExitCode   exitCode        if  options exit  process exit         On  exit   handle the clean up with a new function   function exitHandler exitCode      console log  ExitCode   exitCode       console log  Exiting finally         process on  exit   exitHandler    For the demo purpose  this is link to my gist  In the file  i add a setTimeout to fake the process running   If you run node node-exit-demo js and do nothing  then after 2 seconds  you see the log   The service is finish after a while  ExitCode 0 Exiting finally      Else if before the service finish  you terminate by ctrl C  you ll see    CExitCode SIGINT ExitCode 0 Exiting finally      What happened is the Node process exited initially with code SIGINT  then it routes to process exit   and finally exited with exit code 0

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UPDATE   You can register a handler for process on  exit   and in any other case SIGINT or unhandled exception  to call process exit    process stdin resume     so the program will not close instantly  function exitHandler options  exitCode        if  options cleanup  console log  clean        if  exitCode    exitCode     0  console log exitCode       if  options exit  process exit         do something when app is closing process on  exit   exitHandler bind null  cleanup true        catches ctrl c event process on  SIGINT   exitHandler bind null   exit true         catches  kill pid   for example  nodemon restart  process on  SIGUSR1   exitHandler bind null   exit true     process on  SIGUSR2   exitHandler bind null   exit true        catches uncaught exceptions process on  uncaughtException   exitHandler bind null   exit true

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function fnAsyncTest callback        require  fs   writeFile  async txt    bye    callback      function fnSyncTest         for  var i   0  i  lt  10  i          function killProcess          if  process exitTimeoutId            return             process exitTimeoutId   setTimeout      gt  process exit  5000       console log  process will exit in 5 seconds         fnAsyncTest function             console log  async op  done   arguments                if   fnSyncTest              console log  sync op  done                https   nodejs org api process html process signal events process on  SIGTERM   killProcess   process on  SIGINT   killProcess    process on  uncaughtException   function e         console log   uncaughtException  app will be terminated     e stack        killProcess                    https   nodejs org api process html process event uncaughtexception                  uncaughtException  should be used to perform synchronous cleanup before shutting down the process          It is not safe to resume normal operation after  uncaughtException           If you do use it  restart your application after every unhandled exception                 You have been warned               console log  App is running       console log  Try to press CTRL C or SIGNAL the process with PID     process pid    process stdin resume       just for testing

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io js has an exit and a beforeExit event  which do what you want

[node.js] Doing a cleanup action just before Node.js exits

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