man2/syscalls.2

   1 .\" Copyright (C) 2007 Michael Kerrisk <mtk.manpages@gmail.com>
   2 .\" with some input from Stepan Kasal <kasal@ucw.cz>
   3 .\"
   4 .\" Some content retained from an earlier version of this page:
   5 .\" Copyright (C) 1998 Andries Brouwer (aeb@cwi.nl)
   6 .\" Modifications for 2.2 and 2.4 Copyright (C) 2002 Ian Redfern
   7 .\" <redferni@logica.com>
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  28 .\"
  29 .TH SYSCALLS 2 2012-07-16 "Linux" "Linux Programmer's Manual"
  30 .SH NAME
  31 syscalls \- Linux system calls
  32 .SH SYNOPSIS
  33 Linux system calls.
  34 .SH DESCRIPTION
  35 The system call is the fundamental interface between an application
  36 and the Linux kernel.
  37 .SS System calls and library wrapper functions
  38 System calls are generally not invoked directly,
  39 but rather via wrapper functions in glibc (or perhaps some other library).
  40 For details of direct invocation of a system call, see
  41 .BR intro (2).
  42 Often, but not always, the name of the wrapper function is the same
  43 as the name of the system call that it invokes.
  44 For example, glibc contains a function
  45 .BR truncate ()
  46 which invokes the underlying "truncate" system call.
  47
  48 Often the glibc wrapper function is quite thin, doing little work
  49 other than copying arguments to the right registers
  50 before invoking the system call,
  51 and then setting
  52 .I errno
  53 appropriately after the system call has returned.
  54 (These are the same steps that are performed by
  55 .BR syscall (2),
  56 which can be used to invoke system calls
  57 for which no wrapper function is provided.)
  58 Note: system calls indicate a failure by returning a negative error
  59 number to the caller;
  60 when this happens,
  61 the wrapper function negates the returned error number
  62 (to make it positive), copies it to
  63 .IR errno ,
  64 and returns \-1 to the caller of the wrapper.
  65
  66 Sometimes, however, the wrapper function does some extra work
  67 before invoking the system call.
  68 For example, nowadays there are (for reasons described below) two
  69 related system calls,
  70 .BR truncate (2)
  71 and
  72 .BR truncate64 (2),
  73 and the glibc
  74 .BR truncate ()
  75 wrapper function checks which of those system calls
  76 are provided by the kernel and determines which should be employed.
  77 .SS System call list
  78 Below is a list of those system calls that are common to most platforms.
  79 In the list, the
  80 .I Kernel
  81 column indicates the kernel version
  82 for those system calls that were new in Linux 2.2,
  83 or have appeared since that kernel version.
  84 Note the following points:
  85 .IP * 3
  86 Where no kernel version is indicated,
  87 the system call appeared in kernel 1.0 or earlier.
  88 .IP *
  89 Where a system call is marked "1.2"
  90 this means the system call probably appeared in a 1.1.x kernel version,
  91 and first appeared in a stable kernel with 1.2.
  92 (Development of the 1.2 kernel was initiated from a branch of kernel
  93 1.0.6 via the 1.1.x unstable kernel series.)
  94 .IP *
  95 Where a system call is marked "2.0"
  96 this means the system call probably appeared in a 1.3.x kernel version,
  97 and first appeared in a stable kernel with 2.0.
  98 (Development of the 2.0 kernel was initiated from a branch of kernel
  99 1.2.x, somewhere around 1.2.10,
 100 via the 1.3.x unstable kernel series.)
 101 .\" Was kernel 2.0 started from a branch of 1.2.10?
 102 .\" At least from the timestamps of the tarballs of
 103 .\" of 1.2.10 and 1.3.0, that's how it looks, but in
 104 .\" fact the diff doesn't seem very clear, the
 105 .\" 1.3.0 .tar.bz is much bigger (2.0 MB) than the
 106 .\" 1.2.10 .tar.bz2 (1.8 MB), and AEB points out the
 107 .\" timestamps of some files in 1.3.0 seem to be older
 108 .\" than those in 1.2.10.  All of this suggests
 109 .\" that there might not have been a clean branch point.
 110 .IP *
 111 Where a system call is marked "2.2"
 112 this means the system call probably appeared in a 2.1.x kernel version,
 113 and first appeared in a stable kernel with 2.2.0.
 114 (Development of the 2.2 kernel was initiated from a branch of kernel
 115 2.0.21 via the 2.1.x unstable kernel series.)
 116 .IP *
 117 Where a system call is marked "2.4"
 118 this means the system call probably appeared in a 2.3.x kernel version,
 119 and first appeared in a stable kernel with 2.4.0.
 120 (Development of the 2.4 kernel was initiated from a branch of
 121 kernel 2.2.8 via the 2.3.x unstable kernel series.)
 122 .IP *
 123 Where a system call is marked "2.6"
 124 this means the system call probably appeared in a 2.5.x kernel version,
 125 and first appeared in a stable kernel with 2.6.0.
 126 (Development of kernel 2.6 was initiated from a branch
 127 of kernel 2.4.15 via the 2.5.x unstable kernel series.)
 128 .IP *
 129 Starting with kernel 2.6.0, the development model changed,
 130 and new system calls may appear in each 2.6.x release.
 131 In this case, the exact version number where the system call appeared
 132 is shown.
 133 This convention continues with the 3.x kernel series,
 134 which followed on from kernel 2.6.39.
 135 .IP *
 136 In some cases, a system call was added to a stable kernel
 137 series after it branched from the previous stable kernel
 138 series, and then backported into the earlier stable kernel series.
 139 For example some system calls that appeared in 2.6.x were also backported
 140 into a 2.4.x release after 2.4.15.
 141 When this is so, the version where the system call appeared
 142 in both of the major kernel series is listed.
 143 .PP
 144 The list of system calls that are available as at kernel 3.5
 145 (or in a few cases only on older kernels) is as follows:
 146 .\"
 147 .\" Looking at scripts/checksyscalls.sh in the kernel source is
 148 .\" instructive about i386 specifics.
 149 .\"
 150 .ad l
 151 .TS
 152 l l l
 153 ---
 154 l l l.
 155 \fBSystem call\fP       \fBKernel\fP    \fBNotes\fP
 156
 157 \fB_llseek\fP(2)        1.2
 158 \fB_newselect\fP(2)
 159 \fB_sysctl\fP(2)
 160 \fBaccept\fP(2)
 161 \fBaccept4\fP(2)        2.6.28
 162 \fBaccess\fP(2)
 163 \fBacct\fP(2)
 164 \fBadd_key\fP(2)        2.6.11
 165 \fBadjtimex\fP(2)
 166 \fBalarm\fP(2)
 167 \fBalloc_hugepages\fP(2)        2.5.36  Removed in 2.5.44
 168 \fBbdflush\fP(2)                T{
 169 Deprecated (does nothing) since 2.6
 170 T}
 171 \fBbind\fP(2)
 172 \fBbrk\fP(2)
 173 \fBcacheflush\fP(2)     1.2     Not on i386
 174 \fBcapget\fP(2) 2.2
 175 \fBcapset\fP(2) 2.2
 176 \fBchdir\fP(2)
 177 \fBchmod\fP(2)
 178 \fBchown\fP(2)
 179 \fBchown32\fP(2)        2.4
 180 \fBchroot\fP(2)
 181 \fBclock_adjtime\fP(2)  2.6.39
 182 \fBclock_getres\fP(2)   2.6
 183 \fBclock_gettime\fP(2)  2.6
 184 \fBclock_nanosleep\fP(2)        2.6
 185 \fBclock_settime\fP(2)  2.6
 186 \fBclone\fP(2)
 187 \fBclose\fP(2)
 188 \fBconnect\fP(2)
 189 \fBcreat\fP(2)
 190 \fBcreate_module\fP(2)          Removed in 2.6
 191 \fBdelete_module\fP(2)
 192 \fBdup\fP(2)
 193 \fBdup2\fP(2)
 194 \fBdup3\fP(2)   2.6.27
 195 \fBepoll_create\fP(2)   2.6
 196 \fBepoll_create1\fP(2)  2.6.27
 197 \fBepoll_ctl\fP(2)      2.6
 198 \fBepoll_pwait\fP(2)    2.6.19
 199 \fBepoll_wait\fP(2)     2.6
 200 \fBeventfd\fP(2)        2.6.22
 201 \fBeventfd2\fP(2)       2.6.27
 202 \fBexecve\fP(2)
 203 \fBexit\fP(2)
 204 \fBexit_group\fP(2)     2.6
 205 \fBfaccessat\fP(2)      2.6.16
 206 \fBfadvise64\fP(2)      2.6
 207 .\" Implements \fBposix_fadvise\fP(2)
 208 \fBfadvise64_64\fP(2)   2.6
 209 \fBfallocate\fP(2)      2.6.23
 210 \fBfanotify_init\fP(2)  2.6.37
 211 \fBfanotify_mark\fP(2)  2.6.37
 212 .\" The fanotify calls were added in Linux 2.6.36,
 213 .\" but disabled while the API was finalized.
 214 \fBfchdir\fP(2)
 215 \fBfchmod\fP(2)
 216 \fBfchmodat\fP(2)       2.6.16
 217 \fBfchown\fP(2)
 218 \fBfchown32\fP(2)       2.4
 219 \fBfchownat\fP(2)       2.6.16
 220 \fBfcntl\fP(2)
 221 \fBfcntl64\fP(2)        2.4
 222 \fBfdatasync\fP(2)
 223 \fBfgetxattr\fP(2)      2.6; 2.4.18
 224 \fBflistxattr\fP(2)     2.6; 2.4.18
 225 \fBflock\fP(2)  2.0
 226 \fBfork\fP(2)
 227 \fBfree_hugepages\fP(2) 2.5.36  Removed in 2.5.44
 228 \fBfremovexattr\fP(2)   2.6; 2.4.18
 229 \fBfsetxattr\fP(2)      2.6; 2.4.18
 230 \fBfstat\fP(2)
 231 \fBfstat64\fP(2)        2.4
 232 \fBfstatat64\fP(2)      2.6.16
 233 \fBfstatfs\fP(2)
 234 \fBfstatfs64\fP(2)      2.6
 235 \fBfsync\fP(2)
 236 \fBftruncate\fP(2)
 237 \fBftruncate64\fP(2)    2.4
 238 \fBfutex\fP(2)  2.6
 239 \fBfutimesat\fP(2)      2.6.16
 240 \fBget_kernel_syms\fP(2)                Removed in 2.6
 241 \fBget_mempolicy\fP(2)  2.6.6
 242 \fBget_robust_list\fP(2)        2.6.17
 243 \fBget_thread_area\fP(2)        2.6
 244 \fBgetcpu\fP(2) 2.6.19
 245 \fBgetcwd\fP(2) 2.2
 246 \fBgetdents\fP(2)       2.0
 247 \fBgetdents64\fP(2)     2.4
 248 \fBgetegid\fP(2)
 249 \fBgetegid32\fP(2)      2.4
 250 \fBgeteuid\fP(2)
 251 \fBgeteuid32\fP(2)      2.4
 252 \fBgetgid\fP(2)
 253 \fBgetgid32\fP(2)       2.4
 254 \fBgetgroups\fP(2)
 255 \fBgetgroups32\fP(2)    2.4
 256 \fBgetitimer\fP(2)
 257 \fBgetpeername\fP(2)
 258 \fBgetpagesize\fP(2)    2.0     Not on i386
 259 \fBgetpgid\fP(2)
 260 \fBgetpgrp\fP(2)
 261 \fBgetpid\fP(2)
 262 \fBgetppid\fP(2)
 263 \fBgetpriority\fP(2)
 264 \fBgetresgid\fP(2)      2.2
 265 \fBgetresgid32\fP(2)    2.4
 266 \fBgetresuid\fP(2)      2.2
 267 \fBgetresuid32\fP(2)    2.4
 268 \fBgetrlimit\fP(2)
 269 \fBgetrusage\fP(2)
 270 \fBgetsid\fP(2) 2.0
 271 \fBgetsockname\fP(2)
 272 \fBgetsockopt\fP(2)
 273 \fBgettid\fP(2) 2.4.11
 274 \fBgettimeofday\fP(2)
 275 \fBgetuid\fP(2)
 276 \fBgetuid32\fP(2)       2.4
 277 .\" \fBgetunwind\fP(2)  2.4.8   ia64; DEPRECATED
 278 \fBgetxattr\fP(2)       2.6; 2.4.18
 279 \fBinit_module\fP(2)
 280 \fBinotify_add_watch\fP(2)      2.6.13
 281 \fBinotify_init\fP(2)   2.6.13
 282 \fBinotify_init1\fP(2)  2.6.27
 283 \fBinotify_rm_watch\fP(2)       2.6.13
 284 \fBio_cancel\fP(2)      2.6
 285 \fBio_destroy\fP(2)     2.6
 286 \fBio_getevents\fP(2)   2.6
 287 \fBio_setup\fP(2)       2.6
 288 \fBio_submit\fP(2)      2.6
 289 \fBioctl\fP(2)
 290 \fBioperm\fP(2)
 291 \fBiopl\fP(2)
 292 \fBioprio_get\fP(2)     2.6.13
 293 \fBioprio_set\fP(2)     2.6.13
 294 \fBipc\fP(2)
 295 .\" Implements System V IPC calls
 296 \fBkcmp\fP(2)   3.5
 297 \fBkexec_load\fP(2)     2.6.13
 298 .\" The entry in the syscall table was reserved starting in 2.6.7
 299 .\" Was named sys_kexec_load() from 2.6.7 to 2.6.16
 300 \fBkeyctl\fP(2) 2.6.11
 301 \fBkill\fP(2)
 302 \fBlchown\fP(2) 2.2
 303 \fBlchown32\fP(2)       2.4
 304 \fBlgetxattr\fP(2)      2.6; 2.4.18
 305 \fBlink\fP(2)
 306 \fBlinkat\fP(2) 2.6.16
 307 \fBlisten\fP(2)
 308 \fBlistxattr\fP(2)      2.6; 2.4.18
 309 \fBllistxattr\fP(2)     2.6; 2.4.18
 310 \fBlookup_dcookie\fP(2) 2.6
 311 \fBlremovexattr\fP(2)   2.6; 2.4.18
 312 \fBlseek\fP(2)
 313 \fBlsetxattr\fP(2)      2.6; 2.4.18
 314 \fBlstat\fP(2)
 315 \fBlstat64\fP(2)        2.4
 316 \fBmadvise\fP(2)        2.4
 317 \fBmadvise1\fP(2)       2.4
 318 \fBmbind\fP(2)  2.6.6
 319 .\" \fBmemory_ordering\fP(2)    ???     Sparc64
 320 \fBmigrate_pages\fP(2)  2.6.16
 321 \fBmincore\fP(2)        2.4
 322 \fBmkdir\fP(2)
 323 \fBmkdirat\fP(2)        2.6.16
 324 \fBmknod\fP(2)
 325 \fBmknodat\fP(2)        2.6.16
 326 \fBmlock\fP(2)
 327 \fBmlockall\fP(2)
 328 \fBmmap\fP(2)
 329 \fBmmap2\fP(2)  2.4
 330 \fBmodify_ldt\fP(2)
 331 \fBmount\fP(2)
 332 \fBmove_pages\fP(2)     2.6.18
 333 \fBmprotect\fP(2)
 334 \fBmq_getsetattr\fP(2)  2.6.6
 335 .\" Implements \fBmq_getattr\fP(3) and \fBmq_setattr\fP(3)
 336 \fBmq_notify\fP(2)      2.6.6
 337 \fBmq_open\fP(2)        2.6.6
 338 \fBmq_timedreceive\fP(2)        2.6.6
 339 \fBmq_timedsend\fP(2)   2.6.6
 340 \fBmq_unlink\fP(2)
 341 \fBmremap\fP(2) 2.0
 342 \fBmsgctl\fP(2)
 343 \fBmsgget\fP(2)
 344 \fBmsgrcv\fP(2)
 345 \fBmsgsnd\fP(2)
 346 \fBmsync\fP(2)  2.0
 347 .\" \fBmultiplexer\fP(2)        ??      __NR_multiplexer reserved on
 348 .\"             PowerPC, but unimplemented?
 349 \fBmunlock\fP(2)
 350 \fBmunlockall\fP(2)
 351 \fBmunmap\fP(2)
 352 \fBname_to_handle_at\fP(2)      2.6.39
 353 \fBnanosleep\fP(2)      2.0
 354 \fBnfsservctl\fP(2)     2.2     Removed in 3.1
 355 \fBnice\fP(2)
 356 \fBoldfstat\fP(2)
 357 \fBoldlstat\fP(2)
 358 \fBoldolduname\fP(2)
 359 \fBoldstat\fP(2)
 360 \fBolduname\fP(2)
 361 \fBopen\fP(2)
 362 \fBopen_by_handle_at\fP(2)      2.6.39
 363 \fBopenat\fP(2) 2.6.16
 364 \fBpause\fP(2)
 365 \fBpciconfig_iobase\fP(2)       2.2.15; 2.4     Not on i386
 366 .\" Alpha, PowerPC, ARM; not i386
 367 \fBpciconfig_read\fP(2) 2.0.26; 2.2     Not on i386
 368 .\" , PowerPC, ARM; not i386
 369 \fBpciconfig_write\fP(2)        2.0.26; 2.2     Not on i386
 370 .\" , PowerPC, ARM; not i386
 371 \fBperf_event_open\fP(2)        2.6.31  T{
 372 Was called perf_counter_open() in 2.6.31; renamed in 2.6.32
 373 T}
 374 \fBpersonality\fP(2)    1.2
 375 .\" \fBperfctr\fP(2)    ???     Sparc32, Sparc64
 376 .\" \fBperfmonctl\fP(2) ???     ia64
 377 \fBpipe\fP(2)
 378 \fBpipe2\fP(2)  2.6.27
 379 \fBpivot_root\fP(2)     2.4
 380 \fBpoll\fP(2)   2.2
 381 \fBppoll\fP(2)  2.6.16
 382 \fBprctl\fP(2)  2.2
 383 \fBpread64\fP(2)                T{
 384 Added as "pread" in 2.2; renamed "pread64" in 2.6
 385 T}
 386 \fBpreadv\fP(2) 2.6.30
 387 \fBprlimit\fP(2)        2.6.36
 388 \fBprocess_vm_readv\fP(2)       3.2
 389 \fBprocess_vm_writev\fP(2)      3.2
 390 \fBpselect6\fP(2)       2.6.16
 391 .\" Implements \fBpselect\fP(2)
 392 \fBptrace\fP(2)
 393 \fBpwrite64\fP(2)               T{
 394 Added as "pwrite" in 2.2; renamed "pwrite64" in 2.6
 395 T}
 396 \fBpwritev\fP(2)        2.6.30
 397 \fBquery_module\fP(2)   2.2     Removed in 2.6
 398 \fBquotactl\fP(2)
 399 \fBread\fP(2)
 400 \fBreadahead\fP(2)      2.4.13
 401 \fBreaddir\fP(2)
 402 .\" Supersedes \fBgetdents\fP(2)
 403 \fBreadlink\fP(2)
 404 \fBreadlinkat\fP(2)     2.6.16
 405 \fBreadv\fP(2)  2.0
 406 \fBreboot\fP(2)
 407 \fBrecv\fP(2)
 408 \fBrecvfrom\fP(2)
 409 \fBrecvmsg\fP(2)
 410 \fBrecvmmsg\fP(2)       2.6.33
 411 \fBremap_file_pages\fP(2)       2.6
 412 \fBremovexattr\fP(2)    2.6; 2.4.18
 413 \fBrename\fP(2)
 414 \fBrenameat\fP(2)       2.6.16
 415 \fBrequest_key\fP(2)    2.6.11
 416 \fBrestart_syscall\fP(2)        2.6
 417 \fBrmdir\fP(2)
 418 \fBrt_sigaction\fP(2)   2.2
 419 \fBrt_sigpending\fP(2)  2.2
 420 \fBrt_sigprocmask\fP(2) 2.2
 421 \fBrt_sigqueueinfo\fP(2)        2.2
 422 \fBrt_sigreturn\fP(2)   2.2
 423 \fBrt_sigsuspend\fP(2)  2.2
 424 \fBrt_sigtimedwait\fP(2)        2.2
 425 \fBrt_tgsigqueueinfo\fP(2)      2.6.31
 426 \fBsched_get_priority_max\fP(2) 2.0
 427 \fBsched_get_priority_min\fP(2) 2.0
 428 \fBsched_getaffinity\fP(2)      2.6
 429 \fBsched_getparam\fP(2) 2.0
 430 \fBsched_getscheduler\fP(2)     2.0
 431 \fBsched_rr_get_interval\fP(2)  2.0
 432 \fBsched_setaffinity\fP(2)      2.6
 433 \fBsched_setparam\fP(2) 2.0
 434 \fBsched_setscheduler\fP(2)     2.0
 435 \fBsched_yield\fP(2)    2.0
 436 \fBselect\fP(2)
 437 \fBsemctl\fP(2)
 438 \fBsemget\fP(2)
 439 \fBsemop\fP(2)
 440 \fBsemtimedop\fP(2)     2.6; 2.4.22
 441 \fBsend\fP(2)
 442 \fBsendfile\fP(2)       2.2
 443 \fBsendfile64\fP(2)     2.6; 2.4.19
 444 \fBsendmmsg\fP(2)       3.0
 445 \fBsendmsg\fP(2)
 446 \fBsendto\fP(2)
 447 \fBset_mempolicy\fP(2)  2.6.6
 448 \fBset_robust_list\fP(2)        2.6.17
 449 \fBset_thread_area\fP(2)        2.6
 450 \fBset_tid_address\fP(2)        2.6
 451 .\" See http://lkml.org/lkml/2005/8/1/83
 452 .\" "[PATCH] remove sys_set_zone_reclaim()"
 453 \fBsetdomainname\fP(2)
 454 \fBsetfsgid\fP(2)       1.2
 455 \fBsetfsgid32\fP(2)     2.4
 456 \fBsetfsuid\fP(2)       1.2
 457 \fBsetfsuid32\fP(2)     2.4
 458 \fBsetgid\fP(2)
 459 \fBsetgid32\fP(2)       2.4
 460 \fBsetgroups\fP(2)
 461 \fBsetgroups32\fP(2)    2.4
 462 \fBsethostname\fP(2)
 463 \fBsetitimer\fP(2)
 464 \fBsetns\fP(2)  3.0
 465 \fBsetpgid\fP(2)
 466 \fBsetpriority\fP(2)
 467 \fBsetregid\fP(2)
 468 \fBsetregid32\fP(2)     2.4
 469 \fBsetresgid\fP(2)      2.2
 470 \fBsetresgid32\fP(2)    2.4
 471 \fBsetresuid\fP(2)      2.2
 472 \fBsetresuid32\fP(2)    2.4
 473 \fBsetreuid\fP(2)
 474 \fBsetreuid32\fP(2)     2.4
 475 \fBsetrlimit\fP(2)
 476 \fBsetsid\fP(2)
 477 \fBsetsockopt\fP(2)
 478 \fBsettimeofday\fP(2)
 479 \fBsetuid\fP(2)
 480 \fBsetuid32\fP(2)       2.4
 481 \fBsetup\fP(2)          Removed in 2.2
 482 \fBsetxattr\fP(2)       2.6; 2.4.18
 483 \fBsgetmask\fP(2)
 484 \fBshmat\fP(2)
 485 \fBshmctl\fP(2)
 486 \fBshmdt\fP(2)
 487 \fBshmget\fP(2)
 488 \fBshutdown\fP(2)
 489 \fBsigaction\fP(2)
 490 \fBsigaltstack\fP(2)    2.2
 491 \fBsignal\fP(2)
 492 \fBsignalfd\fP(2)       2.6.22
 493 \fBsignalfd4\fP(2)      2.6.27
 494 \fBsigpending\fP(2)
 495 \fBsigprocmask\fP(2)
 496 \fBsigreturn\fP(2)
 497 \fBsigsuspend\fP(2)
 498 \fBsocket\fP(2)
 499 \fBsocketcall\fP(2)
 500 .\" Implements BSD socket calls
 501 \fBsocketpair\fP(2)
 502 \fBsplice\fP(2) 2.6.17
 503 \fBspu_create\fP(2)     2.6.16  PowerPC only
 504 \fBspu_run\fP(2)        2.6.16  PowerPC only
 505 \fBssetmask\fP(2)
 506 \fBstat\fP(2)
 507 \fBstat64\fP(2) 2.4
 508 \fBstatfs\fP(2)
 509 \fBstatfs64\fP(2)       2.6
 510 \fBstime\fP(2)
 511 \fBsubpage_prot\fP(2)   2.6.25  PowerPC if
 512                 CONFIG_PPC_64K_PAGES
 513 \fBswapoff\fP(2)
 514 \fBswapon\fP(2)
 515 \fBsymlink\fP(2)
 516 \fBsymlinkat\fP(2)      2.6.16
 517 \fBsync\fP(2)
 518 \fBsync_file_range\fP(2)        2.6.17
 519 \fBsync_file_range2\fP(2)       2.6.22  T{
 520 Architecture-specific variant of \fBsync_file_range\fP(2)
 521 T}
 522 .\" PowerPC, ARM, tile
 523 .\" First appeared on ARM, as arm_sync_file_range(), but later renamed
 524 .\" \fBsys_debug_setcontext\fP(2)       ???     PowerPC if CONFIG_PPC32
 525 \fBsyncfs\fP(2) 2.6.39
 526 \fBsysfs\fP(2)  1.2
 527 \fBsysinfo\fP(2)
 528 \fBsyslog\fP(2)
 529 .\" glibc interface is \fBklogctl\fP(3)
 530 \fBtee\fP(2)    2.6.17
 531 \fBtgkill\fP(2) 2.6
 532 \fBtime\fP(2)
 533 \fBtimer_create\fP(2)   2.6
 534 \fBtimer_delete\fP(2)   2.6
 535 \fBtimer_getoverrun\fP(2)       2.6
 536 \fBtimer_gettime\fP(2)  2.6
 537 \fBtimer_settime\fP(2)  2.6
 538 \fBtimerfd_create\fP(2) 2.6.25
 539 \fBtimerfd_gettime\fP(2)        2.6.25
 540 \fBtimerfd_settime\fP(2)        2.6.25
 541 \fBtimes\fP(2)
 542 \fBtkill\fP(2)  2.6; 2.4.22
 543 \fBtruncate\fP(2)
 544 \fBtruncate64\fP(2)     2.4
 545 \fBugetrlimit\fP(2)     2.4
 546 \fBumask\fP(2)
 547 \fBumount\fP(2)
 548 .\" sys_oldumount() -- __NR_umount
 549 \fBumount2\fP(2)        2.2
 550 .\" sys_umount() -- __NR_umount2
 551 \fBuname\fP(2)
 552 \fBunlink\fP(2)
 553 \fBunlinkat\fP(2)       2.6.16
 554 \fBunshare\fP(2)        2.6.16
 555 \fBuselib\fP(2)
 556 \fBustat\fP(2)
 557 \fButime\fP(2)
 558 \fButimensat\fP(2)      2.6.22
 559 \fButimes\fP(2) 2.2
 560 \fBvfork\fP(2)
 561 \fBvhangup\fP(2)
 562 \fBvm86old\fP(2)
 563 .\" Superseded by \fBvm86\fP(2)
 564 \fBvmsplice\fP(2)       2.6.17
 565 \fBwait4\fP(2)
 566 \fBwaitid\fP(2) 2.6.10
 567 \fBwaitpid\fP(2)
 568 \fBwrite\fP(2)
 569 \fBwritev\fP(2) 2.0
 570 .TE
 571 .ad
 572 .PP
 573 On many platforms, including i386, socket calls are all multiplexed
 574 (via glibc wrapper functions) through
 575 .BR socketcall (2)
 576 and similarly System V IPC calls are multiplexed through
 577 .BR ipc (2).
 578
 579 Although slots are reserved for them in the system call table,
 580 the following system calls are not implemented in the standard kernel:
 581 .BR afs_syscall (2), \" __NR_afs_syscall is 53 on Linux 2.6.22/i386
 582 .BR break (2),       \" __NR_break is 17 on Linux 2.6.22/i386
 583 .BR ftime (2),       \" __NR_ftime is 35 on Linux 2.6.22/i386
 584 .BR getpmsg (2),     \" __NR_getpmsg is 188 on Linux 2.6.22/i386
 585 .BR gtty (2),        \" __NR_gtty is 32 on Linux 2.6.22/i386
 586 .BR idle (2),        \" __NR_idle is 112 on Linux 2.6.22/i386
 587 .BR lock (2),        \" __NR_lock is 53 on Linux 2.6.22/i386
 588 .BR madvise1 (2),    \" __NR_madvise1 is 219 on Linux 2.6.22/i386
 589 .BR mpx (2),         \" __NR_mpx is 66 on Linux 2.6.22/i386
 590 .BR phys (2),        \" Slot has been reused
 591 .BR prof (2),        \" __NR_prof is 44 on Linux 2.6.22/i386
 592 .BR profil (2),      \" __NR_profil is 98 on Linux 2.6.22/i386
 593 .BR putpmsg (2),     \" __NR_putpmsg is 189 on Linux 2.6.22/i386
 594 .\" __NR_security is 223 on Linux 2.4/i386; absent on 2.6/i386, present
 595 .\" on a couple of 2.6 architectures
 596 .BR security (2),    \" __NR_security is 223 on Linux 2.4/i386
 597 .\" The security call is for future use.
 598 .BR stty (2),        \" __NR_stty is 31 on Linux 2.6.22/i386
 599 .BR tuxcall (2),     \" __NR_tuxcall is 184 on x86_64, also on PPC and alpha
 600 .BR ulimit (2),      \" __NR_ulimit is 58 on Linux 2.6.22/i386
 601 and
 602 .BR vserver (2)      \" __NR_vserver is 273 on Linux 2.6.22/i386
 603 (see also
 604 .BR unimplemented (2)).
 605 However,
 606 .BR ftime (3),
 607 .BR profil (3)
 608 and
 609 .BR ulimit (3)
 610 exist as library routines.
 611 The slot for
 612 .BR phys (2)
 613 is in use since kernel 2.1.116 for
 614 .BR umount (2);
 615 .BR phys (2)
 616 will never be implemented.
 617 The
 618 .BR getpmsg (2)
 619 and
 620 .BR putpmsg (2)
 621 calls are for kernels patched to support STREAMS,
 622 and may never be in the standard kernel.
 623
 624 There was briefly
 625 .BR set_zone_reclaim (2),
 626 added in Linux 2.6.13, and removed in 2.6.16;
 627 this system call was never available to user space.
 628 .SH NOTES
 629 .PP
 630 Roughly speaking, the code belonging to the system call
 631 with number __NR_xxx defined in
 632 .I /usr/include/asm/unistd.h
 633 can be found in the Linux kernel source in the routine
 634 .IR sys_xxx ().
 635 (The dispatch table for i386 can be found in
 636 .IR /usr/src/linux/arch/i386/kernel/entry.S .)
 637 There are many exceptions, however, mostly because
 638 older system calls were superseded by newer ones,
 639 and this has been treated somewhat unsystematically.
 640 On platforms with
 641 proprietary operating-system emulation,
 642 such as parisc, sparc, sparc64 and alpha,
 643 there are many additional system calls; mips64 also contains a full
 644 set of 32-bit system calls.
 645
 646 Over time, changes to the interfaces of some system calls have been
 647 necessary.
 648 One reason for such changes was the need to increase the size of
 649 structures or scalar values passed to the system call.
 650 Because of these changes, there are now various groups
 651 of related system calls
 652 (e.g.,
 653 .BR truncate (2)
 654 and
 655 .BR truncate64 (2))
 656 which perform similar tasks, but which vary in
 657 details such as the size of their arguments.
 658 (As noted earlier, applications are generally unaware of this:
 659 the glibc wrapper functions do some work to ensure that the right
 660 system call is invoked, and that ABI compatibility is
 661 preserved for old binaries.)
 662 Examples of systems calls that exist in multiple versions are
 663 the following:
 664 .IP * 3
 665 By now there are three different versions of
 666 .BR stat (2):
 667 .IR sys_stat ()
 668 (slot
 669 .IR __NR_oldstat ),
 670 .IR sys_newstat ()
 671 (slot
 672 .IR __NR_stat ),
 673 and
 674 .IR sys_stat64 ()
 675 (slot
 676 .IR __NR_stat64 ),
 677 with the last being the most current.
 678 .\" e.g., on 2.6.22/i386: __NR_oldstat 18, __NR_stat 106, __NR_stat64 195
 679 .\" The stat system calls deal with three different data structures,
 680 .\" defined in include/asm-i386/stat.h: __old_kernel_stat, stat, stat64
 681 A similar story applies for
 682 .BR lstat (2)
 683 and
 684 .BR fstat (2).
 685 .IP *
 686 Similarly, the defines
 687 .IR __NR_oldolduname ,
 688 .IR __NR_olduname ,
 689 and
 690 .I __NR_uname
 691 refer to the routines
 692 .IR sys_olduname (),
 693 .IR sys_uname ()
 694 and
 695 .IR sys_newuname ().
 696 .IP *
 697 In Linux 2.0, a new version of
 698 .BR vm86 (2)
 699 appeared, with the old and the new kernel routines being named
 700 .IR sys_vm86old ()
 701 and
 702 .IR sys_vm86 ().
 703 .IP *
 704 In Linux 2.4, a new version of
 705 .BR getrlimit (2)
 706 appeared, with the old and the new kernel routines being named
 707 .IR sys_old_getrlimit ()
 708 (slot
 709 .IR __NR_getrlimit )
 710 and
 711 .IR sys_getrlimit ()
 712 (slot
 713 .IR __NR_ugetrlimit ).
 714 .IP *
 715 Linux 2.4 increased the size of user and group IDs from 16 to 32 bits.
 716 .\" 64-bit off_t changes: ftruncate64, *stat64,
 717 .\" fcntl64 (because of the flock structure), getdents64, *statfs64
 718 To support this change, a range of system calls were added
 719 (e.g.,
 720 .BR chown32 (2),
 721 .BR getuid32 (2),
 722 .BR getgroups32 (2),
 723 .BR setresuid32 (2)),
 724 superseding earlier calls of the same name without the
 725 "32" suffix.
 726 .IP *
 727 Linux 2.4 added support for applications on 32-bit architectures
 728 to access large files (i.e., files for which the sizes and
 729 file offsets can't be represented in 32 bits.)
 730 To support this change, replacements were required for system calls
 731 that deal with file offsets and sizes.
 732 Thus the following system calls were added:
 733 .BR fcntl64 (2),
 734 .BR ftruncate64 (2),
 735 .BR getdents64 (2),
 736 .BR stat64 (2),
 737 .BR statfs64 (2),
 738 and their analogs that work with file descriptors or
 739 symbolic links.
 740 These system calls supersede the older system calls
 741 which, except in the case of the "stat" calls,
 742 have the same name without the "64" suffix.
 743
 744 On newer platforms that only have 64-bit file access and 32-bit uids
 745 (e.g., alpha, ia64, s390x) there are no *64 or *32 calls.
 746 Where the *64 and *32 calls exist, the other versions are obsolete.
 747 .IP *
 748 The
 749 .I rt_sig*
 750 calls were added in kernel 2.2 to support the addition
 751 of real-time signals (see
 752 .BR signal (7)).
 753 These system calls supersede the older system calls of the same
 754 name without the "rt_" prefix.
 755 .IP *
 756 The
 757 .BR select (2)
 758 and
 759 .BR mmap (2)
 760 system calls use five or more arguments,
 761 which caused problems the way
 762 argument passing on the i386 used to be set up.
 763 Thus, while other architectures have
 764 .IR sys_select ()
 765 and
 766 .IR sys_mmap ()
 767 corresponding to
 768 .I __NR_select
 769 and
 770 .IR __NR_mmap ,
 771 on i386 one finds
 772 .IR old_select ()
 773 and
 774 .IR old_mmap ()
 775 (routines that use a pointer to a
 776 argument block) instead.
 777 These days passing five arguments
 778 is not a problem any more, and there is a
 779 .I __NR__newselect
 780 .\" (used by libc 6)
 781 that corresponds directly to
 782 .IR sys_select ()
 783 and similarly
 784 .IR __NR_mmap2 .
 785 .\" .PP
 786 .\" Two system call numbers,
 787 .\" .IR __NR__llseek
 788 .\" and
 789 .\" .IR __NR__sysctl
 790 .\" have an additional underscore absent in
 791 .\" .IR sys_llseek ()
 792 .\" and
 793 .\" .IR sys_sysctl ().
 794 .\"
 795 .\" In kernel 2.1.81,
 796 .\" .BR lchown (2)
 797 .\" and
 798 .\" .BR chown (2)
 799 .\" were swapped; that is,
 800 .\" .BR lchown (2)
 801 .\" was added with the semantics that were then current for
 802 .\" .BR chown (2),
 803 .\" and the semantics of the latter call were changed to what
 804 .\" they are today.
 805 .SH SEE ALSO
 806 .BR syscall (2),
 807 .BR unimplemented (2),
 808 .BR libc (7)