1# OS 2 3<!--introduced_in=v0.10.0--> 4 5> Stability: 2 - Stable 6 7<!-- source_link=lib/os.js --> 8 9The `os` module provides operating system-related utility methods and 10properties. It can be accessed using: 11 12```js 13const os = require('os'); 14``` 15 16## `os.EOL` 17<!-- YAML 18added: v0.7.8 19--> 20 21* {string} 22 23The operating system-specific end-of-line marker. 24 25* `\n` on POSIX 26* `\r\n` on Windows 27 28## `os.arch()` 29<!-- YAML 30added: v0.5.0 31--> 32 33* Returns: {string} 34 35Returns the operating system CPU architecture for which the Node.js binary was 36compiled. Possible values are `'arm'`, `'arm64'`, `'ia32'`, `'mips'`, 37`'mipsel'`, `'ppc'`, `'ppc64'`, `'s390'`, `'s390x'`, `'x32'`, and `'x64'`. 38 39The return value is equivalent to [`process.arch`][]. 40 41## `os.constants` 42<!-- YAML 43added: v6.3.0 44--> 45 46* {Object} 47 48Contains commonly used operating system-specific constants for error codes, 49process signals, and so on. The specific constants defined are described in 50[OS constants](#os_os_constants_1). 51 52## `os.cpus()` 53<!-- YAML 54added: v0.3.3 55--> 56 57* Returns: {Object[]} 58 59Returns an array of objects containing information about each logical CPU core. 60 61The properties included on each object include: 62 63* `model` {string} 64* `speed` {number} (in MHz) 65* `times` {Object} 66 * `user` {number} The number of milliseconds the CPU has spent in user mode. 67 * `nice` {number} The number of milliseconds the CPU has spent in nice mode. 68 * `sys` {number} The number of milliseconds the CPU has spent in sys mode. 69 * `idle` {number} The number of milliseconds the CPU has spent in idle mode. 70 * `irq` {number} The number of milliseconds the CPU has spent in irq mode. 71 72<!-- eslint-disable semi --> 73```js 74[ 75 { 76 model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz', 77 speed: 2926, 78 times: { 79 user: 252020, 80 nice: 0, 81 sys: 30340, 82 idle: 1070356870, 83 irq: 0 84 } 85 }, 86 { 87 model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz', 88 speed: 2926, 89 times: { 90 user: 306960, 91 nice: 0, 92 sys: 26980, 93 idle: 1071569080, 94 irq: 0 95 } 96 }, 97 { 98 model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz', 99 speed: 2926, 100 times: { 101 user: 248450, 102 nice: 0, 103 sys: 21750, 104 idle: 1070919370, 105 irq: 0 106 } 107 }, 108 { 109 model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz', 110 speed: 2926, 111 times: { 112 user: 256880, 113 nice: 0, 114 sys: 19430, 115 idle: 1070905480, 116 irq: 20 117 } 118 } 119] 120``` 121 122`nice` values are POSIX-only. On Windows, the `nice` values of all processors 123are always 0. 124 125## `os.endianness()` 126<!-- YAML 127added: v0.9.4 128--> 129 130* Returns: {string} 131 132Returns a string identifying the endianness of the CPU for which the Node.js 133binary was compiled. 134 135Possible values are `'BE'` for big endian and `'LE'` for little endian. 136 137## `os.freemem()` 138<!-- YAML 139added: v0.3.3 140--> 141 142* Returns: {integer} 143 144Returns the amount of free system memory in bytes as an integer. 145 146## `os.getPriority([pid])` 147<!-- YAML 148added: v10.10.0 149--> 150 151* `pid` {integer} The process ID to retrieve scheduling priority for. 152 **Default** `0`. 153* Returns: {integer} 154 155Returns the scheduling priority for the process specified by `pid`. If `pid` is 156not provided or is `0`, the priority of the current process is returned. 157 158## `os.homedir()` 159<!-- YAML 160added: v2.3.0 161--> 162 163* Returns: {string} 164 165Returns the string path of the current user's home directory. 166 167On POSIX, it uses the `$HOME` environment variable if defined. Otherwise it 168uses the [effective UID][EUID] to look up the user's home directory. 169 170On Windows, it uses the `USERPROFILE` environment variable if defined. 171Otherwise it uses the path to the profile directory of the current user. 172 173## `os.hostname()` 174<!-- YAML 175added: v0.3.3 176--> 177 178* Returns: {string} 179 180Returns the host name of the operating system as a string. 181 182## `os.loadavg()` 183<!-- YAML 184added: v0.3.3 185--> 186 187* Returns: {number[]} 188 189Returns an array containing the 1, 5, and 15 minute load averages. 190 191The load average is a measure of system activity calculated by the operating 192system and expressed as a fractional number. 193 194The load average is a Unix-specific concept. On Windows, the return value is 195always `[0, 0, 0]`. 196 197## `os.networkInterfaces()` 198<!-- YAML 199added: v0.6.0 200--> 201 202* Returns: {Object} 203 204Returns an object containing network interfaces that have been assigned a 205network address. 206 207Each key on the returned object identifies a network interface. The associated 208value is an array of objects that each describe an assigned network address. 209 210The properties available on the assigned network address object include: 211 212* `address` {string} The assigned IPv4 or IPv6 address 213* `netmask` {string} The IPv4 or IPv6 network mask 214* `family` {string} Either `IPv4` or `IPv6` 215* `mac` {string} The MAC address of the network interface 216* `internal` {boolean} `true` if the network interface is a loopback or 217 similar interface that is not remotely accessible; otherwise `false` 218* `scopeid` {number} The numeric IPv6 scope ID (only specified when `family` 219 is `IPv6`) 220* `cidr` {string} The assigned IPv4 or IPv6 address with the routing prefix 221 in CIDR notation. If the `netmask` is invalid, this property is set 222 to `null`. 223 224<!-- eslint-skip --> 225```js 226{ 227 lo: [ 228 { 229 address: '127.0.0.1', 230 netmask: '255.0.0.0', 231 family: 'IPv4', 232 mac: '00:00:00:00:00:00', 233 internal: true, 234 cidr: '127.0.0.1/8' 235 }, 236 { 237 address: '::1', 238 netmask: 'ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff', 239 family: 'IPv6', 240 mac: '00:00:00:00:00:00', 241 scopeid: 0, 242 internal: true, 243 cidr: '::1/128' 244 } 245 ], 246 eth0: [ 247 { 248 address: '192.168.1.108', 249 netmask: '255.255.255.0', 250 family: 'IPv4', 251 mac: '01:02:03:0a:0b:0c', 252 internal: false, 253 cidr: '192.168.1.108/24' 254 }, 255 { 256 address: 'fe80::a00:27ff:fe4e:66a1', 257 netmask: 'ffff:ffff:ffff:ffff::', 258 family: 'IPv6', 259 mac: '01:02:03:0a:0b:0c', 260 scopeid: 1, 261 internal: false, 262 cidr: 'fe80::a00:27ff:fe4e:66a1/64' 263 } 264 ] 265} 266``` 267 268## `os.platform()` 269<!-- YAML 270added: v0.5.0 271--> 272 273* Returns: {string} 274 275Returns a string identifying the operating system platform. The value is set 276at compile time. Possible values are `'aix'`, `'darwin'`, `'freebsd'`, 277`'linux'`, `'openbsd'`, `'sunos'`, and `'win32'`. 278 279The return value is equivalent to [`process.platform`][]. 280 281The value `'android'` may also be returned if Node.js is built on the Android 282operating system. [Android support is experimental][Android building]. 283 284## `os.release()` 285<!-- YAML 286added: v0.3.3 287--> 288 289* Returns: {string} 290 291Returns the operating system as a string. 292 293On POSIX systems, the operating system release is determined by calling 294[`uname(3)`][]. On Windows, `GetVersionExW()` is used. See 295<https://en.wikipedia.org/wiki/Uname#Examples> for more information. 296 297## `os.setPriority([pid, ]priority)` 298<!-- YAML 299added: v10.10.0 300--> 301 302* `pid` {integer} The process ID to set scheduling priority for. 303 **Default** `0`. 304* `priority` {integer} The scheduling priority to assign to the process. 305 306Attempts to set the scheduling priority for the process specified by `pid`. If 307`pid` is not provided or is `0`, the process ID of the current process is used. 308 309The `priority` input must be an integer between `-20` (high priority) and `19` 310(low priority). Due to differences between Unix priority levels and Windows 311priority classes, `priority` is mapped to one of six priority constants in 312`os.constants.priority`. When retrieving a process priority level, this range 313mapping may cause the return value to be slightly different on Windows. To avoid 314confusion, set `priority` to one of the priority constants. 315 316On Windows, setting priority to `PRIORITY_HIGHEST` requires elevated user 317privileges. Otherwise the set priority will be silently reduced to 318`PRIORITY_HIGH`. 319 320## `os.tmpdir()` 321<!-- YAML 322added: v0.9.9 323changes: 324 - version: v2.0.0 325 pr-url: https://github.com/nodejs/node/pull/747 326 description: This function is now cross-platform consistent and no longer 327 returns a path with a trailing slash on any platform 328--> 329 330* Returns: {string} 331 332Returns the operating system's default directory for temporary files as a 333string. 334 335## `os.totalmem()` 336<!-- YAML 337added: v0.3.3 338--> 339 340* Returns: {integer} 341 342Returns the total amount of system memory in bytes as an integer. 343 344## `os.type()` 345<!-- YAML 346added: v0.3.3 347--> 348 349* Returns: {string} 350 351Returns the operating system name as returned by [`uname(3)`][]. For example, it 352returns `'Linux'` on Linux, `'Darwin'` on macOS, and `'Windows_NT'` on Windows. 353 354See <https://en.wikipedia.org/wiki/Uname#Examples> for additional information 355about the output of running [`uname(3)`][] on various operating systems. 356 357## `os.uptime()` 358<!-- YAML 359added: v0.3.3 360changes: 361 - version: v10.0.0 362 pr-url: https://github.com/nodejs/node/pull/20129 363 description: The result of this function no longer contains a fraction 364 component on Windows. 365--> 366 367* Returns: {integer} 368 369Returns the system uptime in number of seconds. 370 371## `os.userInfo([options])` 372<!-- YAML 373added: v6.0.0 374--> 375 376* `options` {Object} 377 * `encoding` {string} Character encoding used to interpret resulting strings. 378 If `encoding` is set to `'buffer'`, the `username`, `shell`, and `homedir` 379 values will be `Buffer` instances. **Default:** `'utf8'`. 380* Returns: {Object} 381 382Returns information about the currently effective user. On POSIX platforms, 383this is typically a subset of the password file. The returned object includes 384the `username`, `uid`, `gid`, `shell`, and `homedir`. On Windows, the `uid` and 385`gid` fields are `-1`, and `shell` is `null`. 386 387The value of `homedir` returned by `os.userInfo()` is provided by the operating 388system. This differs from the result of `os.homedir()`, which queries 389environment variables for the home directory before falling back to the 390operating system response. 391 392Throws a [`SystemError`][] if a user has no `username` or `homedir`. 393 394## `os.version()` 395<!-- YAML 396added: v12.17.0 397--> 398 399* Returns {string} 400 401Returns a string identifying the kernel version. 402 403On POSIX systems, the operating system release is determined by calling 404[`uname(3)`][]. On Windows, `RtlGetVersion()` is used, and if it is not 405available, `GetVersionExW()` will be used. See 406<https://en.wikipedia.org/wiki/Uname#Examples> for more information. 407 408## OS constants 409 410The following constants are exported by `os.constants`. 411 412Not all constants will be available on every operating system. 413 414### Signal constants 415<!-- YAML 416changes: 417 - version: v5.11.0 418 pr-url: https://github.com/nodejs/node/pull/6093 419 description: Added support for `SIGINFO`. 420--> 421 422The following signal constants are exported by `os.constants.signals`. 423 424<table> 425 <tr> 426 <th>Constant</th> 427 <th>Description</th> 428 </tr> 429 <tr> 430 <td><code>SIGHUP</code></td> 431 <td>Sent to indicate when a controlling terminal is closed or a parent 432 process exits.</td> 433 </tr> 434 <tr> 435 <td><code>SIGINT</code></td> 436 <td>Sent to indicate when a user wishes to interrupt a process 437 (<code>(Ctrl+C)</code>).</td> 438 </tr> 439 <tr> 440 <td><code>SIGQUIT</code></td> 441 <td>Sent to indicate when a user wishes to terminate a process and perform a 442 core dump.</td> 443 </tr> 444 <tr> 445 <td><code>SIGILL</code></td> 446 <td>Sent to a process to notify that it has attempted to perform an illegal, 447 malformed, unknown, or privileged instruction.</td> 448 </tr> 449 <tr> 450 <td><code>SIGTRAP</code></td> 451 <td>Sent to a process when an exception has occurred.</td> 452 </tr> 453 <tr> 454 <td><code>SIGABRT</code></td> 455 <td>Sent to a process to request that it abort.</td> 456 </tr> 457 <tr> 458 <td><code>SIGIOT</code></td> 459 <td>Synonym for <code>SIGABRT</code></td> 460 </tr> 461 <tr> 462 <td><code>SIGBUS</code></td> 463 <td>Sent to a process to notify that it has caused a bus error.</td> 464 </tr> 465 <tr> 466 <td><code>SIGFPE</code></td> 467 <td>Sent to a process to notify that it has performed an illegal arithmetic 468 operation.</td> 469 </tr> 470 <tr> 471 <td><code>SIGKILL</code></td> 472 <td>Sent to a process to terminate it immediately.</td> 473 </tr> 474 <tr> 475 <td><code>SIGUSR1</code> <code>SIGUSR2</code></td> 476 <td>Sent to a process to identify user-defined conditions.</td> 477 </tr> 478 <tr> 479 <td><code>SIGSEGV</code></td> 480 <td>Sent to a process to notify of a segmentation fault.</td> 481 </tr> 482 <tr> 483 <td><code>SIGPIPE</code></td> 484 <td>Sent to a process when it has attempted to write to a disconnected 485 pipe.</td> 486 </tr> 487 <tr> 488 <td><code>SIGALRM</code></td> 489 <td>Sent to a process when a system timer elapses.</td> 490 </tr> 491 <tr> 492 <td><code>SIGTERM</code></td> 493 <td>Sent to a process to request termination.</td> 494 </tr> 495 <tr> 496 <td><code>SIGCHLD</code></td> 497 <td>Sent to a process when a child process terminates.</td> 498 </tr> 499 <tr> 500 <td><code>SIGSTKFLT</code></td> 501 <td>Sent to a process to indicate a stack fault on a coprocessor.</td> 502 </tr> 503 <tr> 504 <td><code>SIGCONT</code></td> 505 <td>Sent to instruct the operating system to continue a paused process.</td> 506 </tr> 507 <tr> 508 <td><code>SIGSTOP</code></td> 509 <td>Sent to instruct the operating system to halt a process.</td> 510 </tr> 511 <tr> 512 <td><code>SIGTSTP</code></td> 513 <td>Sent to a process to request it to stop.</td> 514 </tr> 515 <tr> 516 <td><code>SIGBREAK</code></td> 517 <td>Sent to indicate when a user wishes to interrupt a process.</td> 518 </tr> 519 <tr> 520 <td><code>SIGTTIN</code></td> 521 <td>Sent to a process when it reads from the TTY while in the 522 background.</td> 523 </tr> 524 <tr> 525 <td><code>SIGTTOU</code></td> 526 <td>Sent to a process when it writes to the TTY while in the 527 background.</td> 528 </tr> 529 <tr> 530 <td><code>SIGURG</code></td> 531 <td>Sent to a process when a socket has urgent data to read.</td> 532 </tr> 533 <tr> 534 <td><code>SIGXCPU</code></td> 535 <td>Sent to a process when it has exceeded its limit on CPU usage.</td> 536 </tr> 537 <tr> 538 <td><code>SIGXFSZ</code></td> 539 <td>Sent to a process when it grows a file larger than the maximum 540 allowed.</td> 541 </tr> 542 <tr> 543 <td><code>SIGVTALRM</code></td> 544 <td>Sent to a process when a virtual timer has elapsed.</td> 545 </tr> 546 <tr> 547 <td><code>SIGPROF</code></td> 548 <td>Sent to a process when a system timer has elapsed.</td> 549 </tr> 550 <tr> 551 <td><code>SIGWINCH</code></td> 552 <td>Sent to a process when the controlling terminal has changed its 553 size.</td> 554 </tr> 555 <tr> 556 <td><code>SIGIO</code></td> 557 <td>Sent to a process when I/O is available.</td> 558 </tr> 559 <tr> 560 <td><code>SIGPOLL</code></td> 561 <td>Synonym for <code>SIGIO</code></td> 562 </tr> 563 <tr> 564 <td><code>SIGLOST</code></td> 565 <td>Sent to a process when a file lock has been lost.</td> 566 </tr> 567 <tr> 568 <td><code>SIGPWR</code></td> 569 <td>Sent to a process to notify of a power failure.</td> 570 </tr> 571 <tr> 572 <td><code>SIGINFO</code></td> 573 <td>Synonym for <code>SIGPWR</code></td> 574 </tr> 575 <tr> 576 <td><code>SIGSYS</code></td> 577 <td>Sent to a process to notify of a bad argument.</td> 578 </tr> 579 <tr> 580 <td><code>SIGUNUSED</code></td> 581 <td>Synonym for <code>SIGSYS</code></td> 582 </tr> 583</table> 584 585### Error constants 586 587The following error constants are exported by `os.constants.errno`. 588 589#### POSIX error constants 590 591<table> 592 <tr> 593 <th>Constant</th> 594 <th>Description</th> 595 </tr> 596 <tr> 597 <td><code>E2BIG</code></td> 598 <td>Indicates that the list of arguments is longer than expected.</td> 599 </tr> 600 <tr> 601 <td><code>EACCES</code></td> 602 <td>Indicates that the operation did not have sufficient permissions.</td> 603 </tr> 604 <tr> 605 <td><code>EADDRINUSE</code></td> 606 <td>Indicates that the network address is already in use.</td> 607 </tr> 608 <tr> 609 <td><code>EADDRNOTAVAIL</code></td> 610 <td>Indicates that the network address is currently unavailable for 611 use.</td> 612 </tr> 613 <tr> 614 <td><code>EAFNOSUPPORT</code></td> 615 <td>Indicates that the network address family is not supported.</td> 616 </tr> 617 <tr> 618 <td><code>EAGAIN</code></td> 619 <td>Indicates that there is no data available and to try the 620 operation again later.</td> 621 </tr> 622 <tr> 623 <td><code>EALREADY</code></td> 624 <td>Indicates that the socket already has a pending connection in 625 progress.</td> 626 </tr> 627 <tr> 628 <td><code>EBADF</code></td> 629 <td>Indicates that a file descriptor is not valid.</td> 630 </tr> 631 <tr> 632 <td><code>EBADMSG</code></td> 633 <td>Indicates an invalid data message.</td> 634 </tr> 635 <tr> 636 <td><code>EBUSY</code></td> 637 <td>Indicates that a device or resource is busy.</td> 638 </tr> 639 <tr> 640 <td><code>ECANCELED</code></td> 641 <td>Indicates that an operation was canceled.</td> 642 </tr> 643 <tr> 644 <td><code>ECHILD</code></td> 645 <td>Indicates that there are no child processes.</td> 646 </tr> 647 <tr> 648 <td><code>ECONNABORTED</code></td> 649 <td>Indicates that the network connection has been aborted.</td> 650 </tr> 651 <tr> 652 <td><code>ECONNREFUSED</code></td> 653 <td>Indicates that the network connection has been refused.</td> 654 </tr> 655 <tr> 656 <td><code>ECONNRESET</code></td> 657 <td>Indicates that the network connection has been reset.</td> 658 </tr> 659 <tr> 660 <td><code>EDEADLK</code></td> 661 <td>Indicates that a resource deadlock has been avoided.</td> 662 </tr> 663 <tr> 664 <td><code>EDESTADDRREQ</code></td> 665 <td>Indicates that a destination address is required.</td> 666 </tr> 667 <tr> 668 <td><code>EDOM</code></td> 669 <td>Indicates that an argument is out of the domain of the function.</td> 670 </tr> 671 <tr> 672 <td><code>EDQUOT</code></td> 673 <td>Indicates that the disk quota has been exceeded.</td> 674 </tr> 675 <tr> 676 <td><code>EEXIST</code></td> 677 <td>Indicates that the file already exists.</td> 678 </tr> 679 <tr> 680 <td><code>EFAULT</code></td> 681 <td>Indicates an invalid pointer address.</td> 682 </tr> 683 <tr> 684 <td><code>EFBIG</code></td> 685 <td>Indicates that the file is too large.</td> 686 </tr> 687 <tr> 688 <td><code>EHOSTUNREACH</code></td> 689 <td>Indicates that the host is unreachable.</td> 690 </tr> 691 <tr> 692 <td><code>EIDRM</code></td> 693 <td>Indicates that the identifier has been removed.</td> 694 </tr> 695 <tr> 696 <td><code>EILSEQ</code></td> 697 <td>Indicates an illegal byte sequence.</td> 698 </tr> 699 <tr> 700 <td><code>EINPROGRESS</code></td> 701 <td>Indicates that an operation is already in progress.</td> 702 </tr> 703 <tr> 704 <td><code>EINTR</code></td> 705 <td>Indicates that a function call was interrupted.</td> 706 </tr> 707 <tr> 708 <td><code>EINVAL</code></td> 709 <td>Indicates that an invalid argument was provided.</td> 710 </tr> 711 <tr> 712 <td><code>EIO</code></td> 713 <td>Indicates an otherwise unspecified I/O error.</td> 714 </tr> 715 <tr> 716 <td><code>EISCONN</code></td> 717 <td>Indicates that the socket is connected.</td> 718 </tr> 719 <tr> 720 <td><code>EISDIR</code></td> 721 <td>Indicates that the path is a directory.</td> 722 </tr> 723 <tr> 724 <td><code>ELOOP</code></td> 725 <td>Indicates too many levels of symbolic links in a path.</td> 726 </tr> 727 <tr> 728 <td><code>EMFILE</code></td> 729 <td>Indicates that there are too many open files.</td> 730 </tr> 731 <tr> 732 <td><code>EMLINK</code></td> 733 <td>Indicates that there are too many hard links to a file.</td> 734 </tr> 735 <tr> 736 <td><code>EMSGSIZE</code></td> 737 <td>Indicates that the provided message is too long.</td> 738 </tr> 739 <tr> 740 <td><code>EMULTIHOP</code></td> 741 <td>Indicates that a multihop was attempted.</td> 742 </tr> 743 <tr> 744 <td><code>ENAMETOOLONG</code></td> 745 <td>Indicates that the filename is too long.</td> 746 </tr> 747 <tr> 748 <td><code>ENETDOWN</code></td> 749 <td>Indicates that the network is down.</td> 750 </tr> 751 <tr> 752 <td><code>ENETRESET</code></td> 753 <td>Indicates that the connection has been aborted by the network.</td> 754 </tr> 755 <tr> 756 <td><code>ENETUNREACH</code></td> 757 <td>Indicates that the network is unreachable.</td> 758 </tr> 759 <tr> 760 <td><code>ENFILE</code></td> 761 <td>Indicates too many open files in the system.</td> 762 </tr> 763 <tr> 764 <td><code>ENOBUFS</code></td> 765 <td>Indicates that no buffer space is available.</td> 766 </tr> 767 <tr> 768 <td><code>ENODATA</code></td> 769 <td>Indicates that no message is available on the stream head read 770 queue.</td> 771 </tr> 772 <tr> 773 <td><code>ENODEV</code></td> 774 <td>Indicates that there is no such device.</td> 775 </tr> 776 <tr> 777 <td><code>ENOENT</code></td> 778 <td>Indicates that there is no such file or directory.</td> 779 </tr> 780 <tr> 781 <td><code>ENOEXEC</code></td> 782 <td>Indicates an exec format error.</td> 783 </tr> 784 <tr> 785 <td><code>ENOLCK</code></td> 786 <td>Indicates that there are no locks available.</td> 787 </tr> 788 <tr> 789 <td><code>ENOLINK</code></td> 790 <td>Indications that a link has been severed.</td> 791 </tr> 792 <tr> 793 <td><code>ENOMEM</code></td> 794 <td>Indicates that there is not enough space.</td> 795 </tr> 796 <tr> 797 <td><code>ENOMSG</code></td> 798 <td>Indicates that there is no message of the desired type.</td> 799 </tr> 800 <tr> 801 <td><code>ENOPROTOOPT</code></td> 802 <td>Indicates that a given protocol is not available.</td> 803 </tr> 804 <tr> 805 <td><code>ENOSPC</code></td> 806 <td>Indicates that there is no space available on the device.</td> 807 </tr> 808 <tr> 809 <td><code>ENOSR</code></td> 810 <td>Indicates that there are no stream resources available.</td> 811 </tr> 812 <tr> 813 <td><code>ENOSTR</code></td> 814 <td>Indicates that a given resource is not a stream.</td> 815 </tr> 816 <tr> 817 <td><code>ENOSYS</code></td> 818 <td>Indicates that a function has not been implemented.</td> 819 </tr> 820 <tr> 821 <td><code>ENOTCONN</code></td> 822 <td>Indicates that the socket is not connected.</td> 823 </tr> 824 <tr> 825 <td><code>ENOTDIR</code></td> 826 <td>Indicates that the path is not a directory.</td> 827 </tr> 828 <tr> 829 <td><code>ENOTEMPTY</code></td> 830 <td>Indicates that the directory is not empty.</td> 831 </tr> 832 <tr> 833 <td><code>ENOTSOCK</code></td> 834 <td>Indicates that the given item is not a socket.</td> 835 </tr> 836 <tr> 837 <td><code>ENOTSUP</code></td> 838 <td>Indicates that a given operation is not supported.</td> 839 </tr> 840 <tr> 841 <td><code>ENOTTY</code></td> 842 <td>Indicates an inappropriate I/O control operation.</td> 843 </tr> 844 <tr> 845 <td><code>ENXIO</code></td> 846 <td>Indicates no such device or address.</td> 847 </tr> 848 <tr> 849 <td><code>EOPNOTSUPP</code></td> 850 <td>Indicates that an operation is not supported on the socket. Although 851 <code>ENOTSUP</code> and <code>EOPNOTSUPP</code> have the same value 852 on Linux, according to POSIX.1 these error values should be distinct.)</td> 853 </tr> 854 <tr> 855 <td><code>EOVERFLOW</code></td> 856 <td>Indicates that a value is too large to be stored in a given data 857 type.</td> 858 </tr> 859 <tr> 860 <td><code>EPERM</code></td> 861 <td>Indicates that the operation is not permitted.</td> 862 </tr> 863 <tr> 864 <td><code>EPIPE</code></td> 865 <td>Indicates a broken pipe.</td> 866 </tr> 867 <tr> 868 <td><code>EPROTO</code></td> 869 <td>Indicates a protocol error.</td> 870 </tr> 871 <tr> 872 <td><code>EPROTONOSUPPORT</code></td> 873 <td>Indicates that a protocol is not supported.</td> 874 </tr> 875 <tr> 876 <td><code>EPROTOTYPE</code></td> 877 <td>Indicates the wrong type of protocol for a socket.</td> 878 </tr> 879 <tr> 880 <td><code>ERANGE</code></td> 881 <td>Indicates that the results are too large.</td> 882 </tr> 883 <tr> 884 <td><code>EROFS</code></td> 885 <td>Indicates that the file system is read only.</td> 886 </tr> 887 <tr> 888 <td><code>ESPIPE</code></td> 889 <td>Indicates an invalid seek operation.</td> 890 </tr> 891 <tr> 892 <td><code>ESRCH</code></td> 893 <td>Indicates that there is no such process.</td> 894 </tr> 895 <tr> 896 <td><code>ESTALE</code></td> 897 <td>Indicates that the file handle is stale.</td> 898 </tr> 899 <tr> 900 <td><code>ETIME</code></td> 901 <td>Indicates an expired timer.</td> 902 </tr> 903 <tr> 904 <td><code>ETIMEDOUT</code></td> 905 <td>Indicates that the connection timed out.</td> 906 </tr> 907 <tr> 908 <td><code>ETXTBSY</code></td> 909 <td>Indicates that a text file is busy.</td> 910 </tr> 911 <tr> 912 <td><code>EWOULDBLOCK</code></td> 913 <td>Indicates that the operation would block.</td> 914 </tr> 915 <tr> 916 <td><code>EXDEV</code></td> 917 <td>Indicates an improper link. 918 </tr> 919</table> 920 921#### Windows-specific error constants 922 923The following error codes are specific to the Windows operating system. 924 925<table> 926 <tr> 927 <th>Constant</th> 928 <th>Description</th> 929 </tr> 930 <tr> 931 <td><code>WSAEINTR</code></td> 932 <td>Indicates an interrupted function call.</td> 933 </tr> 934 <tr> 935 <td><code>WSAEBADF</code></td> 936 <td>Indicates an invalid file handle.</td> 937 </tr> 938 <tr> 939 <td><code>WSAEACCES</code></td> 940 <td>Indicates insufficient permissions to complete the operation.</td> 941 </tr> 942 <tr> 943 <td><code>WSAEFAULT</code></td> 944 <td>Indicates an invalid pointer address.</td> 945 </tr> 946 <tr> 947 <td><code>WSAEINVAL</code></td> 948 <td>Indicates that an invalid argument was passed.</td> 949 </tr> 950 <tr> 951 <td><code>WSAEMFILE</code></td> 952 <td>Indicates that there are too many open files.</td> 953 </tr> 954 <tr> 955 <td><code>WSAEWOULDBLOCK</code></td> 956 <td>Indicates that a resource is temporarily unavailable.</td> 957 </tr> 958 <tr> 959 <td><code>WSAEINPROGRESS</code></td> 960 <td>Indicates that an operation is currently in progress.</td> 961 </tr> 962 <tr> 963 <td><code>WSAEALREADY</code></td> 964 <td>Indicates that an operation is already in progress.</td> 965 </tr> 966 <tr> 967 <td><code>WSAENOTSOCK</code></td> 968 <td>Indicates that the resource is not a socket.</td> 969 </tr> 970 <tr> 971 <td><code>WSAEDESTADDRREQ</code></td> 972 <td>Indicates that a destination address is required.</td> 973 </tr> 974 <tr> 975 <td><code>WSAEMSGSIZE</code></td> 976 <td>Indicates that the message size is too long.</td> 977 </tr> 978 <tr> 979 <td><code>WSAEPROTOTYPE</code></td> 980 <td>Indicates the wrong protocol type for the socket.</td> 981 </tr> 982 <tr> 983 <td><code>WSAENOPROTOOPT</code></td> 984 <td>Indicates a bad protocol option.</td> 985 </tr> 986 <tr> 987 <td><code>WSAEPROTONOSUPPORT</code></td> 988 <td>Indicates that the protocol is not supported.</td> 989 </tr> 990 <tr> 991 <td><code>WSAESOCKTNOSUPPORT</code></td> 992 <td>Indicates that the socket type is not supported.</td> 993 </tr> 994 <tr> 995 <td><code>WSAEOPNOTSUPP</code></td> 996 <td>Indicates that the operation is not supported.</td> 997 </tr> 998 <tr> 999 <td><code>WSAEPFNOSUPPORT</code></td> 1000 <td>Indicates that the protocol family is not supported.</td> 1001 </tr> 1002 <tr> 1003 <td><code>WSAEAFNOSUPPORT</code></td> 1004 <td>Indicates that the address family is not supported.</td> 1005 </tr> 1006 <tr> 1007 <td><code>WSAEADDRINUSE</code></td> 1008 <td>Indicates that the network address is already in use.</td> 1009 </tr> 1010 <tr> 1011 <td><code>WSAEADDRNOTAVAIL</code></td> 1012 <td>Indicates that the network address is not available.</td> 1013 </tr> 1014 <tr> 1015 <td><code>WSAENETDOWN</code></td> 1016 <td>Indicates that the network is down.</td> 1017 </tr> 1018 <tr> 1019 <td><code>WSAENETUNREACH</code></td> 1020 <td>Indicates that the network is unreachable.</td> 1021 </tr> 1022 <tr> 1023 <td><code>WSAENETRESET</code></td> 1024 <td>Indicates that the network connection has been reset.</td> 1025 </tr> 1026 <tr> 1027 <td><code>WSAECONNABORTED</code></td> 1028 <td>Indicates that the connection has been aborted.</td> 1029 </tr> 1030 <tr> 1031 <td><code>WSAECONNRESET</code></td> 1032 <td>Indicates that the connection has been reset by the peer.</td> 1033 </tr> 1034 <tr> 1035 <td><code>WSAENOBUFS</code></td> 1036 <td>Indicates that there is no buffer space available.</td> 1037 </tr> 1038 <tr> 1039 <td><code>WSAEISCONN</code></td> 1040 <td>Indicates that the socket is already connected.</td> 1041 </tr> 1042 <tr> 1043 <td><code>WSAENOTCONN</code></td> 1044 <td>Indicates that the socket is not connected.</td> 1045 </tr> 1046 <tr> 1047 <td><code>WSAESHUTDOWN</code></td> 1048 <td>Indicates that data cannot be sent after the socket has been 1049 shutdown.</td> 1050 </tr> 1051 <tr> 1052 <td><code>WSAETOOMANYREFS</code></td> 1053 <td>Indicates that there are too many references.</td> 1054 </tr> 1055 <tr> 1056 <td><code>WSAETIMEDOUT</code></td> 1057 <td>Indicates that the connection has timed out.</td> 1058 </tr> 1059 <tr> 1060 <td><code>WSAECONNREFUSED</code></td> 1061 <td>Indicates that the connection has been refused.</td> 1062 </tr> 1063 <tr> 1064 <td><code>WSAELOOP</code></td> 1065 <td>Indicates that a name cannot be translated.</td> 1066 </tr> 1067 <tr> 1068 <td><code>WSAENAMETOOLONG</code></td> 1069 <td>Indicates that a name was too long.</td> 1070 </tr> 1071 <tr> 1072 <td><code>WSAEHOSTDOWN</code></td> 1073 <td>Indicates that a network host is down.</td> 1074 </tr> 1075 <tr> 1076 <td><code>WSAEHOSTUNREACH</code></td> 1077 <td>Indicates that there is no route to a network host.</td> 1078 </tr> 1079 <tr> 1080 <td><code>WSAENOTEMPTY</code></td> 1081 <td>Indicates that the directory is not empty.</td> 1082 </tr> 1083 <tr> 1084 <td><code>WSAEPROCLIM</code></td> 1085 <td>Indicates that there are too many processes.</td> 1086 </tr> 1087 <tr> 1088 <td><code>WSAEUSERS</code></td> 1089 <td>Indicates that the user quota has been exceeded.</td> 1090 </tr> 1091 <tr> 1092 <td><code>WSAEDQUOT</code></td> 1093 <td>Indicates that the disk quota has been exceeded.</td> 1094 </tr> 1095 <tr> 1096 <td><code>WSAESTALE</code></td> 1097 <td>Indicates a stale file handle reference.</td> 1098 </tr> 1099 <tr> 1100 <td><code>WSAEREMOTE</code></td> 1101 <td>Indicates that the item is remote.</td> 1102 </tr> 1103 <tr> 1104 <td><code>WSASYSNOTREADY</code></td> 1105 <td>Indicates that the network subsystem is not ready.</td> 1106 </tr> 1107 <tr> 1108 <td><code>WSAVERNOTSUPPORTED</code></td> 1109 <td>Indicates that the <code>winsock.dll</code> version is out of 1110 range.</td> 1111 </tr> 1112 <tr> 1113 <td><code>WSANOTINITIALISED</code></td> 1114 <td>Indicates that successful WSAStartup has not yet been performed.</td> 1115 </tr> 1116 <tr> 1117 <td><code>WSAEDISCON</code></td> 1118 <td>Indicates that a graceful shutdown is in progress.</td> 1119 </tr> 1120 <tr> 1121 <td><code>WSAENOMORE</code></td> 1122 <td>Indicates that there are no more results.</td> 1123 </tr> 1124 <tr> 1125 <td><code>WSAECANCELLED</code></td> 1126 <td>Indicates that an operation has been canceled.</td> 1127 </tr> 1128 <tr> 1129 <td><code>WSAEINVALIDPROCTABLE</code></td> 1130 <td>Indicates that the procedure call table is invalid.</td> 1131 </tr> 1132 <tr> 1133 <td><code>WSAEINVALIDPROVIDER</code></td> 1134 <td>Indicates an invalid service provider.</td> 1135 </tr> 1136 <tr> 1137 <td><code>WSAEPROVIDERFAILEDINIT</code></td> 1138 <td>Indicates that the service provider failed to initialized.</td> 1139 </tr> 1140 <tr> 1141 <td><code>WSASYSCALLFAILURE</code></td> 1142 <td>Indicates a system call failure.</td> 1143 </tr> 1144 <tr> 1145 <td><code>WSASERVICE_NOT_FOUND</code></td> 1146 <td>Indicates that a service was not found.</td> 1147 </tr> 1148 <tr> 1149 <td><code>WSATYPE_NOT_FOUND</code></td> 1150 <td>Indicates that a class type was not found.</td> 1151 </tr> 1152 <tr> 1153 <td><code>WSA_E_NO_MORE</code></td> 1154 <td>Indicates that there are no more results.</td> 1155 </tr> 1156 <tr> 1157 <td><code>WSA_E_CANCELLED</code></td> 1158 <td>Indicates that the call was canceled.</td> 1159 </tr> 1160 <tr> 1161 <td><code>WSAEREFUSED</code></td> 1162 <td>Indicates that a database query was refused.</td> 1163 </tr> 1164</table> 1165 1166### dlopen constants 1167 1168If available on the operating system, the following constants 1169are exported in `os.constants.dlopen`. See dlopen(3) for detailed 1170information. 1171 1172<table> 1173 <tr> 1174 <th>Constant</th> 1175 <th>Description</th> 1176 </tr> 1177 <tr> 1178 <td><code>RTLD_LAZY</code></td> 1179 <td>Perform lazy binding. Node.js sets this flag by default.</td> 1180 </tr> 1181 <tr> 1182 <td><code>RTLD_NOW</code></td> 1183 <td>Resolve all undefined symbols in the library before dlopen(3) 1184 returns.</td> 1185 </tr> 1186 <tr> 1187 <td><code>RTLD_GLOBAL</code></td> 1188 <td>Symbols defined by the library will be made available for symbol 1189 resolution of subsequently loaded libraries.</td> 1190 </tr> 1191 <tr> 1192 <td><code>RTLD_LOCAL</code></td> 1193 <td>The converse of <code>RTLD_GLOBAL</code>. This is the default behavior 1194 if neither flag is specified.</td> 1195 </tr> 1196 <tr> 1197 <td><code>RTLD_DEEPBIND</code></td> 1198 <td>Make a self-contained library use its own symbols in preference to 1199 symbols from previously loaded libraries.</td> 1200 </tr> 1201</table> 1202 1203### Priority constants 1204<!-- YAML 1205added: v10.10.0 1206--> 1207 1208The following process scheduling constants are exported by 1209`os.constants.priority`. 1210 1211<table> 1212 <tr> 1213 <th>Constant</th> 1214 <th>Description</th> 1215 </tr> 1216 <tr> 1217 <td><code>PRIORITY_LOW</code></td> 1218 <td>The lowest process scheduling priority. This corresponds to 1219 <code>IDLE_PRIORITY_CLASS</code> on Windows, and a nice value of 1220 <code>19</code> on all other platforms.</td> 1221 </tr> 1222 <tr> 1223 <td><code>PRIORITY_BELOW_NORMAL</code></td> 1224 <td>The process scheduling priority above <code>PRIORITY_LOW</code> and 1225 below <code>PRIORITY_NORMAL</code>. This corresponds to 1226 <code>BELOW_NORMAL_PRIORITY_CLASS</code> on Windows, and a nice value of 1227 <code>10</code> on all other platforms.</td> 1228 </tr> 1229 <tr> 1230 <td><code>PRIORITY_NORMAL</code></td> 1231 <td>The default process scheduling priority. This corresponds to 1232 <code>NORMAL_PRIORITY_CLASS</code> on Windows, and a nice value of 1233 <code>0</code> on all other platforms.</td> 1234 </tr> 1235 <tr> 1236 <td><code>PRIORITY_ABOVE_NORMAL</code></td> 1237 <td>The process scheduling priority above <code>PRIORITY_NORMAL</code> and 1238 below <code>PRIORITY_HIGH</code>. This corresponds to 1239 <code>ABOVE_NORMAL_PRIORITY_CLASS</code> on Windows, and a nice value of 1240 <code>-7</code> on all other platforms.</td> 1241 </tr> 1242 <tr> 1243 <td><code>PRIORITY_HIGH</code></td> 1244 <td>The process scheduling priority above <code>PRIORITY_ABOVE_NORMAL</code> 1245 and below <code>PRIORITY_HIGHEST</code>. This corresponds to 1246 <code>HIGH_PRIORITY_CLASS</code> on Windows, and a nice value of 1247 <code>-14</code> on all other platforms.</td> 1248 </tr> 1249 <tr> 1250 <td><code>PRIORITY_HIGHEST</code></td> 1251 <td>The highest process scheduling priority. This corresponds to 1252 <code>REALTIME_PRIORITY_CLASS</code> on Windows, and a nice value of 1253 <code>-20</code> on all other platforms.</td> 1254 </tr> 1255</table> 1256 1257### libuv constants 1258 1259<table> 1260 <tr> 1261 <th>Constant</th> 1262 <th>Description</th> 1263 </tr> 1264 <tr> 1265 <td><code>UV_UDP_REUSEADDR</code></td> 1266 <td></td> 1267 </tr> 1268</table> 1269 1270[`SystemError`]: errors.html#errors_class_systemerror 1271[`process.arch`]: process.html#process_process_arch 1272[`process.platform`]: process.html#process_process_platform 1273[`uname(3)`]: https://linux.die.net/man/3/uname 1274[Android building]: https://github.com/nodejs/node/blob/master/BUILDING.md#androidandroid-based-devices-eg-firefox-os 1275[EUID]: https://en.wikipedia.org/wiki/User_identifier#Effective_user_ID 1276