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   syscalls    ( 2 )

системные вызовы Linux (Linux system calls)

  Name  |  Synopsis  |    Description    |  Note  |  See also  |

Описание (Description)

The system call is the fundamental interface between an application and the Linux kernel.

System calls and library wrapper functions System calls are generally not invoked directly, but rather via wrapper functions in glibc (or perhaps some other library). For details of direct invocation of a system call, see intro(2). Often, but not always, the name of the wrapper function is the same as the name of the system call that it invokes. For example, glibc contains a function chdir() which invokes the underlying "chdir" system call.

Often the glibc wrapper function is quite thin, doing little work other than copying arguments to the right registers before invoking the system call, and then setting errno appropriately after the system call has returned. (These are the same steps that are performed by syscall(2), which can be used to invoke system calls for which no wrapper function is provided.) Note: system calls indicate a failure by returning a negative error number to the caller on architectures without a separate error register/flag, as noted in syscall(2); when this happens, the wrapper function negates the returned error number (to make it positive), copies it to errno, and returns -1 to the caller of the wrapper.

Sometimes, however, the wrapper function does some extra work before invoking the system call. For example, nowadays there are (for reasons described below) two related system calls, truncate(2) and truncate64(2), and the glibc truncate() wrapper function checks which of those system calls are provided by the kernel and determines which should be employed.

System call list Below is a list of the Linux system calls. In the list, the Kernel column indicates the kernel version for those system calls that were new in Linux 2.2, or have appeared since that kernel version. Note the following points:

* Where no kernel version is indicated, the system call appeared in kernel 1.0 or earlier.

* Where a system call is marked "1.2" this means the system call probably appeared in a 1.1.x kernel version, and first appeared in a stable kernel with 1.2. (Development of the 1.2 kernel was initiated from a branch of kernel 1.0.6 via the 1.1.x unstable kernel series.)

* Where a system call is marked "2.0" this means the system call probably appeared in a 1.3.x kernel version, and first appeared in a stable kernel with 2.0. (Development of the 2.0 kernel was initiated from a branch of kernel 1.2.x, somewhere around 1.2.10, via the 1.3.x unstable kernel series.)

* Where a system call is marked "2.2" this means the system call probably appeared in a 2.1.x kernel version, and first appeared in a stable kernel with 2.2.0. (Development of the 2.2 kernel was initiated from a branch of kernel 2.0.21 via the 2.1.x unstable kernel series.)

* Where a system call is marked "2.4" this means the system call probably appeared in a 2.3.x kernel version, and first appeared in a stable kernel with 2.4.0. (Development of the 2.4 kernel was initiated from a branch of kernel 2.2.8 via the 2.3.x unstable kernel series.)

* Where a system call is marked "2.6" this means the system call probably appeared in a 2.5.x kernel version, and first appeared in a stable kernel with 2.6.0. (Development of kernel 2.6 was initiated from a branch of kernel 2.4.15 via the 2.5.x unstable kernel series.)

* Starting with kernel 2.6.0, the development model changed, and new system calls may appear in each 2.6.x release. In this case, the exact version number where the system call appeared is shown. This convention continues with the 3.x kernel series, which followed on from kernel 2.6.39; and the 4.x kernel series, which followed on from kernel 3.19; and the 5.x kernel series, which followed on from kernel 4.20.

* In some cases, a system call was added to a stable kernel series after it branched from the previous stable kernel series, and then backported into the earlier stable kernel series. For example some system calls that appeared in 2.6.x were also backported into a 2.4.x release after 2.4.15. When this is so, the version where the system call appeared in both of the major kernel series is listed.

The list of system calls that are available as at kernel 5.11 (or in a few cases only on older kernels) is as follows:

System call Kernel Notes ──────────────────────────────────────────────────────────────────────

_llseek(2) 1.2 _newselect(2) 2.0 _sysctl(2) 2.0 Removed in 5.5 accept(2) 2.0 See notes on socketcall(2) accept4(2) 2.6.28 access(2) 1.0 acct(2) 1.0 add_key(2) 2.6.10 adjtimex(2) 1.0 alarm(2) 1.0 alloc_hugepages(2) 2.5.36 Removed in 2.5.44 arc_gettls(2) 3.9 ARC only arc_settls(2) 3.9 ARC only arc_usr_cmpxchg(2) 4.9 ARC only arch_prctl(2) 2.6 x86_64, x86 since 4.12 atomic_barrier(2) 2.6.34 m68k only atomic_cmpxchg_32(2) 2.6.34 m68k only bdflush(2) 1.2 Deprecated (does nothing) since 2.6 bind(2) 2.0 See notes on socketcall(2) bpf(2) 3.18 brk(2) 1.0 breakpoint(2) 2.2 ARM OABI only, defined with __ARM_NR prefix cacheflush(2) 1.2 Not on x86 capget(2) 2.2 capset(2) 2.2

chdir(2) 1.0 chmod(2) 1.0 chown(2) 2.2 See chown(2) for version details chown32(2) 2.4 chroot(2) 1.0 clock_adjtime(2) 2.6.39 clock_getres(2) 2.6 clock_gettime(2) 2.6 clock_nanosleep(2) 2.6 clock_settime(2) 2.6 clone2(2) 2.4 IA-64 only clone(2) 1.0 clone3(2) 5.3 close(2) 1.0 close_range(2) 5.9 connect(2) 2.0 See notes on socketcall(2) copy_file_range(2) 4.5 creat(2) 1.0 create_module(2) 1.0 Removed in 2.6 delete_module(2) 1.0 dup(2) 1.0 dup2(2) 1.0 dup3(2) 2.6.27 epoll_create(2) 2.6 epoll_create1(2) 2.6.27 epoll_ctl(2) 2.6 epoll_pwait(2) 2.6.19 epoll_pwait2(2) 5.11 epoll_wait(2) 2.6 eventfd(2) 2.6.22 eventfd2(2) 2.6.27 execv(2) 2.0 SPARC/SPARC64 only, for compatibility with SunOS execve(2) 1.0 execveat(2) 3.19 exit(2) 1.0 exit_group(2) 2.6 faccessat(2) 2.6.16 faccessat2(2) 5.8 fadvise64(2) 2.6 fadvise64_64(2) 2.6 fallocate(2) 2.6.23 fanotify_init(2) 2.6.37 fanotify_mark(2) 2.6.37 fchdir(2) 1.0 fchmod(2) 1.0 fchmodat(2) 2.6.16 fchown(2) 1.0 fchown32(2) 2.4 fchownat(2) 2.6.16 fcntl(2) 1.0 fcntl64(2) 2.4 fdatasync(2) 2.0 fgetxattr(2) 2.6; 2.4.18 finit_module(2) 3.8 flistxattr(2) 2.6; 2.4.18 flock(2) 2.0 fork(2) 1.0 free_hugepages(2) 2.5.36 Removed in 2.5.44 fremovexattr(2) 2.6; 2.4.18 fsconfig(2) 5.2 fsetxattr(2) 2.6; 2.4.18 fsmount(2) 5.2 fsopen(2) 5.2

fspick(2) 5.2 fstat(2) 1.0 fstat64(2) 2.4 fstatat64(2) 2.6.16 fstatfs(2) 1.0 fstatfs64(2) 2.6 fsync(2) 1.0 ftruncate(2) 1.0 ftruncate64(2) 2.4 futex(2) 2.6 futimesat(2) 2.6.16 get_kernel_syms(2) 1.0 Removed in 2.6 get_mempolicy(2) 2.6.6 get_robust_list(2) 2.6.17 get_thread_area(2) 2.6 get_tls(2) 4.15 ARM OABI only, has __ARM_NR prefix getcpu(2) 2.6.19 getcwd(2) 2.2 getdents(2) 2.0 getdents64(2) 2.4 getdomainname(2) 2.2 SPARC, SPARC64; available as osf_getdomainname(2) on Alpha since Linux 2.0 getdtablesize(2) 2.0 SPARC (removed in 2.6.26), available on Alpha as osf_getdtablesize(2) getegid(2) 1.0 getegid32(2) 2.4 geteuid(2) 1.0 geteuid32(2) 2.4 getgid(2) 1.0 getgid32(2) 2.4 getgroups(2) 1.0 getgroups32(2) 2.4 gethostname(2) 2.0 Alpha, was available on SPARC up to Linux 2.6.26 getitimer(2) 1.0 getpeername(2) 2.0 See notes on socketcall(2) getpagesize(2) 2.0 Not on x86 getpgid(2) 1.0 getpgrp(2) 1.0 getpid(2) 1.0 getppid(2) 1.0 getpriority(2) 1.0 getrandom(2) 3.17 getresgid(2) 2.2 getresgid32(2) 2.4 getresuid(2) 2.2 getresuid32(2) 2.4 getrlimit(2) 1.0 getrusage(2) 1.0 getsid(2) 2.0 getsockname(2) 2.0 See notes on socketcall(2) getsockopt(2) 2.0 See notes on socketcall(2) gettid(2) 2.4.11 gettimeofday(2) 1.0 getuid(2) 1.0 getuid32(2) 2.4 getunwind(2) 2.4.8 IA-64 only; deprecated getxattr(2) 2.6; 2.4.18 getxgid(2) 2.0 Alpha only; see NOTES getxpid(2) 2.0 Alpha only; see NOTES getxuid(2) 2.0 Alpha only; see NOTES init_module(2) 1.0

inotify_add_watch(2) 2.6.13 inotify_init(2) 2.6.13 inotify_init1(2) 2.6.27 inotify_rm_watch(2) 2.6.13 io_cancel(2) 2.6 io_destroy(2) 2.6 io_getevents(2) 2.6 io_pgetevents(2) 4.18 io_setup(2) 2.6 io_submit(2) 2.6 io_uring_enter(2) 5.1 io_uring_register(2) 5.1 io_uring_setup(2) 5.1 ioctl(2) 1.0 ioperm(2) 1.0 iopl(2) 1.0 ioprio_get(2) 2.6.13 ioprio_set(2) 2.6.13 ipc(2) 1.0 kcmp(2) 3.5 kern_features(2) 3.7 SPARC64 only kexec_file_load(2) 3.17 kexec_load(2) 2.6.13 keyctl(2) 2.6.10 kill(2) 1.0 landlock_add_rule(2) 5.13 landlock_create_ruleset(2) 5.13 landlock_restrict_self(2) 5.13 landlock_add_rule(2) 5.13 lchown(2) 1.0 See chown(2) for version details lchown32(2) 2.4 lgetxattr(2) 2.6; 2.4.18 link(2) 1.0 linkat(2) 2.6.16 listen(2) 2.0 See notes on socketcall(2) listxattr(2) 2.6; 2.4.18 llistxattr(2) 2.6; 2.4.18 lookup_dcookie(2) 2.6 lremovexattr(2) 2.6; 2.4.18 lseek(2) 1.0 lsetxattr(2) 2.6; 2.4.18 lstat(2) 1.0 lstat64(2) 2.4 madvise(2) 2.4 mbind(2) 2.6.6 memory_ordering(2) 2.2 SPARC64 only membarrier(2) 3.17 memfd_create(2) 3.17 migrate_pages(2) 2.6.16 mincore(2) 2.4 mkdir(2) 1.0 mkdirat(2) 2.6.16 mknod(2) 1.0 mknodat(2) 2.6.16 mlock(2) 2.0 mlock2(2) 4.4 mlockall(2) 2.0 mmap(2) 1.0 mmap2(2) 2.4 modify_ldt(2) 1.0 mount(2) 1.0 move_mount(2) 5.2 move_pages(2) 2.6.18 mprotect(2) 1.0

mq_getsetattr(2) 2.6.6 mq_notify(2) 2.6.6 mq_open(2) 2.6.6 mq_timedreceive(2) 2.6.6 mq_timedsend(2) 2.6.6 mq_unlink(2) 2.6.6 mremap(2) 2.0 msgctl(2) 2.0 See notes on ipc(2) msgget(2) 2.0 See notes on ipc(2) msgrcv(2) 2.0 See notes on ipc(2) msgsnd(2) 2.0 See notes on ipc(2) msync(2) 2.0 munlock(2) 2.0 munlockall(2) 2.0 munmap(2) 1.0 name_to_handle_at(2) 2.6.39 nanosleep(2) 2.0 newfstatat(2) 2.6.16 See stat(2) nfsservctl(2) 2.2 Removed in 3.1 nice(2) 1.0 old_adjtimex(2) 2.0 Alpha only; see NOTES old_getrlimit(2) 2.4 Old variant of getrlimit(2) that used a different value for RLIM_INFINITY oldfstat(2) 1.0 oldlstat(2) 1.0 oldolduname(2) 1.0 oldstat(2) 1.0 oldumount(2) 2.4.116 Name of the old umount(2) syscall on Alpha olduname(2) 1.0 open(2) 1.0 open_by_handle_at(2) 2.6.39 open_tree(2) 5.2 openat(2) 2.6.16 openat2(2) 5.6 or1k_atomic(2) 3.1 OpenRISC 1000 only pause(2) 1.0 pciconfig_iobase(2) 2.2.15; 2.4 Not on x86 pciconfig_read(2) 2.0.26; 2.2 Not on x86 pciconfig_write(2) 2.0.26; 2.2 Not on x86 perf_event_open(2) 2.6.31 Was perf_counter_open() in 2.6.31; renamed in 2.6.32 personality(2) 1.2 perfctr(2) 2.2 SPARC only; removed in 2.6.34 perfmonctl(2) 2.4 IA-64 only; removed in 5.10 pidfd_getfd(2) 5.6 pidfd_send_signal(2) 5.1 pidfd_open(2) 5.3 pipe(2) 1.0 pipe2(2) 2.6.27 pivot_root(2) 2.4 pkey_alloc(2) 4.8 pkey_free(2) 4.8 pkey_mprotect(2) 4.8 poll(2) 2.0.36; 2.2 ppoll(2) 2.6.16 prctl(2) 2.2 pread64(2) Added as "pread" in 2.2; renamed "pread64" in 2.6 preadv(2) 2.6.30 preadv2(2) 4.6 prlimit64(2) 2.6.36 process_madvise(2) 5.10

process_vm_readv(2) 3.2 process_vm_writev(2) 3.2 pselect6(2) 2.6.16 ptrace(2) 1.0 pwrite64(2) Added as "pwrite" in 2.2; renamed "pwrite64" in 2.6 pwritev(2) 2.6.30 pwritev2(2) 4.6 query_module(2) 2.2 Removed in 2.6 quotactl(2) 1.0 quotactl_fd(2) 5.14 read(2) 1.0 readahead(2) 2.4.13 readdir(2) 1.0 readlink(2) 1.0 readlinkat(2) 2.6.16 readv(2) 2.0 reboot(2) 1.0 recv(2) 2.0 See notes on socketcall(2) recvfrom(2) 2.0 See notes on socketcall(2) recvmsg(2) 2.0 See notes on socketcall(2) recvmmsg(2) 2.6.33 remap_file_pages(2) 2.6 Deprecated since 3.16 removexattr(2) 2.6; 2.4.18 rename(2) 1.0 renameat(2) 2.6.16 renameat2(2) 3.15 request_key(2) 2.6.10 restart_syscall(2) 2.6 riscv_flush_icache(2) 4.15 RISC-V only rmdir(2) 1.0 rseq(2) 4.18 rt_sigaction(2) 2.2 rt_sigpending(2) 2.2 rt_sigprocmask(2) 2.2 rt_sigqueueinfo(2) 2.2 rt_sigreturn(2) 2.2 rt_sigsuspend(2) 2.2 rt_sigtimedwait(2) 2.2 rt_tgsigqueueinfo(2) 2.6.31 rtas(2) 2.6.2 PowerPC/PowerPC64 only s390_runtime_instr(2) 3.7 s390 only s390_pci_mmio_read(2) 3.19 s390 only s390_pci_mmio_write(2) 3.19 s390 only s390_sthyi(2) 4.15 s390 only s390_guarded_storage(2) 4.12 s390 only sched_get_affinity(2) 2.6 Name of sched_getaffinity(2) on SPARC and SPARC64 sched_get_priority_max(2) 2.0 sched_get_priority_min(2) 2.0 sched_getaffinity(2) 2.6 sched_getattr(2) 3.14 sched_getparam(2) 2.0 sched_getscheduler(2) 2.0 sched_rr_get_interval(2) 2.0 sched_set_affinity(2) 2.6 Name of sched_setaffinity(2) on SPARC and SPARC64 sched_setaffinity(2) 2.6 sched_setattr(2) 3.14 sched_setparam(2) 2.0 sched_setscheduler(2) 2.0 sched_yield(2) 2.0 seccomp(2) 3.17

select(2) 1.0 semctl(2) 2.0 See notes on ipc(2) semget(2) 2.0 See notes on ipc(2) semop(2) 2.0 See notes on ipc(2) semtimedop(2) 2.6; 2.4.22 send(2) 2.0 See notes on socketcall(2) sendfile(2) 2.2 sendfile64(2) 2.6; 2.4.19 sendmmsg(2) 3.0 sendmsg(2) 2.0 See notes on socketcall(2) sendto(2) 2.0 See notes on socketcall(2) set_mempolicy(2) 2.6.6 set_robust_list(2) 2.6.17 set_thread_area(2) 2.6 set_tid_address(2) 2.6 set_tls(2) 2.6.11 ARM OABI/EABI only (constant has __ARM_NR prefix) setdomainname(2) 1.0 setfsgid(2) 1.2 setfsgid32(2) 2.4 setfsuid(2) 1.2 setfsuid32(2) 2.4 setgid(2) 1.0 setgid32(2) 2.4 setgroups(2) 1.0 setgroups32(2) 2.4 sethae(2) 2.0 Alpha only; see NOTES sethostname(2) 1.0 setitimer(2) 1.0 setns(2) 3.0 setpgid(2) 1.0 setpgrp(2) 2.0 Alternative name for setpgid(2) on Alpha setpriority(2) 1.0 setregid(2) 1.0 setregid32(2) 2.4 setresgid(2) 2.2 setresgid32(2) 2.4 setresuid(2) 2.2 setresuid32(2) 2.4 setreuid(2) 1.0 setreuid32(2) 2.4 setrlimit(2) 1.0 setsid(2) 1.0 setsockopt(2) 2.0 See notes on socketcall(2) settimeofday(2) 1.0 setuid(2) 1.0 setuid32(2) 2.4 setup(2) 1.0 Removed in 2.2 setxattr(2) 2.6; 2.4.18 sgetmask(2) 1.0 shmat(2) 2.0 See notes on ipc(2) shmctl(2) 2.0 See notes on ipc(2) shmdt(2) 2.0 See notes on ipc(2) shmget(2) 2.0 See notes on ipc(2) shutdown(2) 2.0 See notes on socketcall(2) sigaction(2) 1.0 sigaltstack(2) 2.2 signal(2) 1.0 signalfd(2) 2.6.22 signalfd4(2) 2.6.27 sigpending(2) 1.0 sigprocmask(2) 1.0 sigreturn(2) 1.0

sigsuspend(2) 1.0 socket(2) 2.0 See notes on socketcall(2) socketcall(2) 1.0 socketpair(2) 2.0 See notes on socketcall(2) spill(2) 2.6.13 Xtensa only splice(2) 2.6.17 spu_create(2) 2.6.16 PowerPC/PowerPC64 only spu_run(2) 2.6.16 PowerPC/PowerPC64 only ssetmask(2) 1.0 stat(2) 1.0 stat64(2) 2.4 statfs(2) 1.0 statfs64(2) 2.6 statx(2) 4.11 stime(2) 1.0 subpage_prot(2) 2.6.25 PowerPC/PowerPC64 only swapcontext(2) 2.6.3 PowerPC/PowerPC64 only switch_endian(2) 4.1 PowerPC64 only swapoff(2) 1.0 swapon(2) 1.0 symlink(2) 1.0 symlinkat(2) 2.6.16 sync(2) 1.0 sync_file_range(2) 2.6.17 sync_file_range2(2) 2.6.22 syncfs(2) 2.6.39 sys_debug_setcontext(2) 2.6.11 PowerPC only syscall(2) 1.0 Still available on ARM OABI and MIPS O32 ABI sysfs(2) 1.2 sysinfo(2) 1.0 syslog(2) 1.0 sysmips(2) 2.6.0 MIPS only tee(2) 2.6.17 tgkill(2) 2.6 time(2) 1.0 timer_create(2) 2.6 timer_delete(2) 2.6 timer_getoverrun(2) 2.6 timer_gettime(2) 2.6 timer_settime(2) 2.6 timerfd_create(2) 2.6.25 timerfd_gettime(2) 2.6.25 timerfd_settime(2) 2.6.25 times(2) 1.0 tkill(2) 2.6; 2.4.22 truncate(2) 1.0 truncate64(2) 2.4 ugetrlimit(2) 2.4 umask(2) 1.0 umount(2) 1.0 umount2(2) 2.2 uname(2) 1.0 unlink(2) 1.0 unlinkat(2) 2.6.16 unshare(2) 2.6.16 uselib(2) 1.0 ustat(2) 1.0 userfaultfd(2) 4.3 usr26(2) 2.4.8.1 ARM OABI only usr32(2) 2.4.8.1 ARM OABI only utime(2) 1.0 utimensat(2) 2.6.22 utimes(2) 2.2 utrap_install(2) 2.2 SPARC64 only

vfork(2) 2.2 vhangup(2) 1.0 vm86old(2) 1.0 Was "vm86"; renamed in 2.0.28/2.2 vm86(2) 2.0.28; 2.2 vmsplice(2) 2.6.17 wait4(2) 1.0 waitid(2) 2.6.10 waitpid(2) 1.0 write(2) 1.0 writev(2) 2.0 xtensa(2) 2.6.13 Xtensa only

On many platforms, including x86-32, socket calls are all multiplexed (via glibc wrapper functions) through socketcall(2) and similarly System V IPC calls are multiplexed through ipc(2).

Although slots are reserved for them in the system call table, the following system calls are not implemented in the standard kernel: afs_syscall(2), break(2), ftime(2), getpmsg(2), gtty(2), idle(2), lock(2), madvise1(2), mpx(2), phys(2), prof(2), profil(2), putpmsg(2), security(2), stty(2), tuxcall(2), ulimit(2), and vserver(2) (see also unimplemented(2)). However, ftime(3), profil(3), and ulimit(3) exist as library routines. The slot for phys(2) is in use since kernel 2.1.116 for umount(2); phys(2) will never be implemented. The getpmsg(2) and putpmsg(2) calls are for kernels patched to support STREAMS, and may never be in the standard kernel.

There was briefly set_zone_reclaim(2), added in Linux 2.6.13, and removed in 2.6.16; this system call was never available to user space.

System calls on removed ports Some system calls only ever existed on Linux architectures that have since been removed from the kernel:

AVR32 (port removed in Linux 4.12) * pread(2) * pwrite(2)

Blackfin (port removed in Linux 4.17) * bfin_spinlock(2) (added in Linux 2.6.22) * dma_memcpy(2) (added in Linux 2.6.22) * pread(2) (added in Linux 2.6.22) * pwrite(2) (added in Linux 2.6.22) * sram_alloc(2) (added in Linux 2.6.22) * sram_free(2) (added in Linux 2.6.22)

Metag (port removed in Linux 4.17) * metag_get_tls(2) (add in Linux 3.9) * metag_set_fpu_flags(2) (add in Linux 3.9) * metag_set_tls(2) (add in Linux 3.9) * metag_setglobalbit(2) (add in Linux 3.9)

Tile (port removed in Linux 4.17) * cmpxchg_badaddr(2) (added in Linux 2.6.36)