{"id":2102,"date":"2022-08-30T15:22:04","date_gmt":"2022-08-30T15:22:04","guid":{"rendered":"https:\/\/unknownerror.org\/index.php\/2013\/12\/26\/where-do-npm-background-scripts-go-collection-of-common-programming-errors\/"},"modified":"2022-08-30T15:22:04","modified_gmt":"2022-08-30T15:22:04","slug":"where-do-npm-background-scripts-go-collection-of-common-programming-errors","status":"publish","type":"post","link":"https:\/\/unknownerror.org\/index.php\/2022\/08\/30\/where-do-npm-background-scripts-go-collection-of-common-programming-errors\/","title":{"rendered":"Where do npm background scripts go?-Collection of common programming errors"},"content":{"rendered":"

I have a program which relies on another program being run so I added this build<\/code> command to my package.json<\/code> file<\/p>\n

\"scripts\": {\n    \"start\": \"brunch watch --server\",\n    \"build\": \"coffee server\/modules\/events\/book_server.coffee &\"\n  }\n<\/code><\/pre>\n
so before I run my main script with npm start<\/code> I run npm run-script build<\/code> which makes my main script work, however when I quit my main script and then look for background processes with bg<\/code> I get the message<\/p>\n
> -bash: bg: current: no such job\n<\/code><\/pre>\n
so I decided to run npm run-script build<\/code> again however the previous process must still have been running because I got the error message<\/p>\n
events.js:66\n        throw arguments[1]; \/\/ Unhandled 'error' event\n                       ^\nError: listen EADDRINUSE\n  at errnoException (net.js:776:11)\n  at Server._listen2._connectionKey (net.js:917:26)\n  at process.startup.processNextTick.process._tickCallback (node.js:244:9)\n<\/code><\/pre>\n
and when I tried to run my main program again I got the error<\/p>\n
> TypeError: Cannot read property 'port' of null\n<\/code><\/pre>\n
My question is, where are these background scripts?<\/p>\n
So far I have looked in all the obvious places including package.json<\/code>‘s directory the directory for book_server.coffee<\/code> and in node_modules<\/code> but with no luck.<\/p>\n
    \n
  1. \n
    So the background processes go into the background just running inside the OS but not attached to your shell’s tty. To find them, use jobs -l<\/code> or the ps<\/code> command with something like ps -ef<\/code>. You can use grep<\/code> to filter the output, but what you need to find is the process ID (PID) of your build process so you can stop it with kill<\/code> . You may also want to read up on pgrep<\/code> and pkill<\/code> which are handy for this process.<\/p>\n
    Note that in your example you use bg<\/code> when it’s not appropriate. bg<\/code> is for this sequence: 1. start a job in your shell’s foreground, 2. suspend that job with CTRL-Z, 3. use bg<\/code> to tell the shell “allow this job to continue executing, but detached from my tty in the background”. (again, jobs<\/code> is what you are looking for here).<\/p>\n
    For the bigger picture, there’s no need or benefit of running that coffee<\/code> command in the background as it is just a simple compliation step that should take on the order of a few milliseconds.<\/p>\n
    For an amazingly-detailed “reread every year” level of depth, check out The TTY demystified.<\/p>\n<\/li>\n<\/ol>\n
    Originally posted 2013-12-26 03:15:16. <\/small><\/p>","protected":false},"excerpt":{"rendered":"
    I have a program which relies on another program being run so I added this build command to my package.json file “scripts”: { “start”: “brunch watch –server”, “build”: “coffee server\/modules\/events\/book_server.coffee &” } so before I run my main script with npm start I run npm run-script build which makes my main script work, however when […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-2102","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/2102","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/comments?post=2102"}],"version-history":[{"count":0,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/posts\/2102\/revisions"}],"wp:attachment":[{"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/media?parent=2102"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/categories?post=2102"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/unknownerror.org\/index.php\/wp-json\/wp\/v2\/tags?post=2102"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}