Section 2: system calls
mknod, mknodat – create a special or ordinary file Synopsis#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <unistd.h> int mknod(const char *pathname, mode_t mode, dev_t dev); #include <fcntl.h> /* Definition of AT_* constants */ #include <sys/stat.h> int mknodat(int dirfd, const char *pathname, mode_t mode, dev_t dev);Feature Test Macro Requirements for glibc (see feature_test_macros(7)): mknod(): _XOPEN_SOURCE >= 500 || /* Since…
mkdir, mkdirat – create a directory Synopsis#include <sys/stat.h> #include <sys/types.h> int mkdir(const char *pathname, mode_t mode); #include <fcntl.h> /* Definition of AT_* constants */ #include <sys/stat.h> int mkdirat(int dirfd, const char *pathname, mode_t mode);Feature Test Macro Requirements for glibc (see feature_test_macros(7)): mkdirat(): Since glibc 2.10: _POSIX_C_SOURCE >= 200809L Before glibc 2.10: _ATFILE_SOURCEDescriptionmkdir() attempts to create a directory…
mkdir, mkdirat – create a directory Synopsis#include <sys/stat.h> #include <sys/types.h> int mkdir(const char *pathname, mode_t mode); #include <fcntl.h> /* Definition of AT_* constants */ #include <sys/stat.h> int mkdirat(int dirfd, const char *pathname, mode_t mode);Feature Test Macro Requirements for glibc (see feature_test_macros(7)): mkdirat(): Since glibc 2.10: _POSIX_C_SOURCE >= 200809L Before glibc 2.10: _ATFILE_SOURCEDescriptionmkdir() attempts to create a directory…
mincore – determine whether pages are resident in memory Synopsis#include <unistd.h> #include <sys/mman.h> int mincore(void *addr, size_t length, unsigned char *vec); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): mincore(): Since glibc 2.19: _DEFAULT_SOURCE Glibc 2.19 and earlier: _BSD_SOURCE || _SVID_SOURCE Descriptionmincore() returns a vector that indicates whether pages of the calling process’s virtual memory are…
migrate_pages – move all pages in a process to another set of nodes Synopsis#include <numaif.h> long migrate_pages(int pid, unsigned long maxnode, const unsigned long *old_nodes, const unsigned long *new_nodes);Link with -lnuma. Descriptionmigrate_pages() attempts to move all pages of the process pid that are in memory nodes old_nodes to the memory nodes in new_nodes. Pages not…
memfd_create – create an anonymous file Synopsis#define _GNU_SOURCE /* See feature_test_macros(7) */ #include <sys/mman.h> int memfd_create(const char *name, unsigned int flags);Descriptionmemfd_create() creates an anonymous file and returns a file descriptor that refers to it. The file behaves like a regular file, and so can be modified, truncated, memory-mapped, and so on. However, unlike a regular…
membarrier – issue memory barriers on a set of threads Synopsis#include <linux/membarrier.h> int membarrier(int cmd, unsigned int flags, int cpu_id);Note: There is no glibc wrapper for this system call; see NOTES. DescriptionThe membarrier() system call helps reducing the overhead of the memory barrier instructions required to order memory accesses on multi-core systems. However, this system…
mbind – set memory policy for a memory range Synopsis#include <numaif.h> long mbind(void *addr, unsigned long len, int mode, const unsigned long *nodemask, unsigned long maxnode, unsigned flags); Link with -lnuma.Descriptionmbind() sets the NUMA memory policy, which consists of a policy mode and zero or more nodes, for the memory range starting with addr and…
afs_syscall, break, fattach, fdetach, ftime, getmsg, getpmsg, gtty, isastream, lock, madvise1, mpx, prof, profil, putmsg, putpmsg, security, stty, tuxcall, ulimit, vserver – unimplemented system calls SynopsisUnimplemented system calls. DescriptionThese system calls are not implemented in the Linux kernel. Return ValueThese system calls always return -1 and set errno to ENOSYS. NotesNote that ftime(3), profil(3), and…
madvise – give advice about use of memory Synopsis#include <sys/mman.h> int madvise(void *addr, size_t length, int advice); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): madvise(): Since glibc 2.19: _DEFAULT_SOURCE Up to and including glibc 2.19: _BSD_SOURCEDescriptionThe madvise() system call is used to give advice or directions to the kernel about the address range beginning…
stat, fstat, lstat, fstatat – get file status Synopsis#include <sys/types.h> #include <sys/stat.h> #include <unistd.h> int stat(const char *pathname, struct stat *statbuf); int fstat(int fd, struct stat *statbuf); int lstat(const char *pathname, struct stat *statbuf); #include <fcntl.h> /* Definition of AT_* constants */ #include <sys/stat.h> int fstatat(int dirfd, const char *pathname, struct stat *statbuf, int flags);Feature…
stat, fstat, lstat, fstatat – get file status Synopsis#include <sys/types.h> #include <sys/stat.h> #include <unistd.h> int stat(const char *pathname, struct stat *statbuf); int fstat(int fd, struct stat *statbuf); int lstat(const char *pathname, struct stat *statbuf); #include <fcntl.h> /* Definition of AT_* constants */ #include <sys/stat.h> int fstatat(int dirfd, const char *pathname, struct stat *statbuf, int flags);Feature…
setxattr, lsetxattr, fsetxattr – set an extended attribute value Synopsis#include <sys/types.h> #include <sys/xattr.h> int setxattr(const char *path, const char *name, const void *value, size_t size, int flags); int lsetxattr(const char *path, const char *name, const void *value, size_t size, int flags); int fsetxattr(int fd, const char *name, const void *value, size_t size, int flags);DescriptionExtended attributes are name:value pairs associated with inodes (files, directories,…
lseek – reposition read/write file offset Synopsis#include <sys/types.h> #include <unistd.h> off_t lseek(int fd, off_t offset, int whence); Descriptionlseek() repositions the file offset of the open file description associated with the file descriptor fd to the argument offset according to the directive whence as follows: SEEK_SET The file offset is set to offset bytes. SEEK_CUR The…
removexattr, lremovexattr, fremovexattr – remove an extended attribute Synopsis#include <sys/types.h> #include <sys/xattr.h> int removexattr(const char *path, const char *name); int lremovexattr(const char *path, const char *name); int fremovexattr(int fd, const char *name);DescriptionExtended attributes are name:value pairs associated with inodes (files, directories, symbolic links, etc.). They are extensions to the normal attributes which are associated with all inodes in the system…
lookup_dcookie – return a directory entry’s path Synopsisint lookup_dcookie(u64 cookie, char *buffer, size_t len); DescriptionLook up the full path of the directory entry specified by the value cookie. The cookie is an opaque identifier uniquely identifying a particular directory entry. The buffer given is filled in with the full path of the directory entry. For…
afs_syscall, break, fattach, fdetach, ftime, getmsg, getpmsg, gtty, isastream, lock, madvise1, mpx, prof, profil, putmsg, putpmsg, security, stty, tuxcall, ulimit, vserver – unimplemented system calls SynopsisUnimplemented system calls. DescriptionThese system calls are not implemented in the Linux kernel. Return ValueThese system calls always return -1 and set errno to ENOSYS. NotesNote that ftime(3), profil(3), and…
_llseek – reposition read/write file offset Synopsis#include <sys/types.h> #include <unistd.h> int _llseek(unsigned int fd, unsigned long offset_high, unsigned long offset_low, loff_t *result, unsigned int whence);Note: There is no glibc wrapper for this system call; see NOTES. DescriptionNote: for information about the llseek(3) library function, see lseek64(3). The _llseek() system call repositions the offset of the…
listxattr, llistxattr, flistxattr – list extended attribute names Synopsis#include <sys/types.h> #include <sys/xattr.h> ssize_t listxattr(const char *path, char *list, size_t size); ssize_t llistxattr(const char *path, char *list, size_t size); ssize_t flistxattr(int fd, char *list, size_t size);DescriptionExtended attributes are name:value pairs associated with inodes (files, directories, symbolic links, etc.). They are extensions to the normal attributes which are associated with all inodes…
listxattr, llistxattr, flistxattr – list extended attribute names Synopsis#include <sys/types.h> #include <sys/xattr.h> ssize_t listxattr(const char *path, char *list, size_t size); ssize_t llistxattr(const char *path, char *list, size_t size); ssize_t flistxattr(int fd, char *list, size_t size);DescriptionExtended attributes are name:value pairs associated with inodes (files, directories, symbolic links, etc.). They are extensions to the normal attributes which are associated with all inodes…