Linux Manuals session 2

truncate, ftruncate – truncate a file to a specified length Synopsis#include <unistd.h> #include <sys/types.h> int truncate(const char *path, off_t length); int ftruncate(int fd, off_t length); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): truncate(): _XOPEN_SOURCE >= 500     || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L     || /* Glibc versions <= 2.19: */ _BSD_SOURCE ftruncate(): _XOPEN_SOURCE >= 500     || /* Since glibc 2.3.5: */ _POSIX_C_SOURCE >= 200112L     || /* Glibc versions <= 2.19: */ _BSD_SOURCEDescriptionThe truncate() and ftruncate() functions cause the regular file…

truncate, ftruncate – truncate a file to a specified length Synopsis#include <unistd.h> #include <sys/types.h> int truncate(const char *path, off_t length); int ftruncate(int fd, off_t length); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): truncate(): _XOPEN_SOURCE >= 500     || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L     || /* Glibc versions <= 2.19: */ _BSD_SOURCE ftruncate(): _XOPEN_SOURCE >= 500     || /* Since glibc 2.3.5: */ _POSIX_C_SOURCE >= 200112L     || /* Glibc versions <= 2.19: */ _BSD_SOURCEDescriptionThe truncate() and ftruncate() functions cause the regular file…

fsync, fdatasync – synchronize a file’s in-core state with storage device Synopsis#include <unistd.h> int fsync(int fd); int fdatasync(int fd); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): fsync():     Glibc 2.16 and later:         No feature test macros need be defined     Glibc up to and including 2.15:         _BSD_SOURCE || _XOPEN_SOURCE             || /* since glibc 2.8: */ _POSIX_C_SOURCE >= 200112L fdatasync():     _POSIX_C_SOURCE >= 199309L || _XOPEN_SOURCE >= 500 Descriptionfsync() transfers…

statvfs, fstatvfs – get filesystem statistics Synopsis#include <sys/statvfs.h> int statvfs(const char *path, struct statvfs *buf); int fstatvfs(int fd, struct statvfs *buf); DescriptionThe function statvfs() returns information about a mounted filesystem. path is the pathname of any file within the mounted filesystem. buf is a pointer to a statvfs structure defined approximately as follows: struct statvfs…

statfs, fstatfs – get filesystem statistics Synopsis#include <sys/vfs.h> /* or <sys/statfs.h> */ int statfs(const char *path, struct statfs *buf); int fstatfs(int fd, struct statfs *buf); DescriptionThe statfs() system call returns information about a mounted filesystem. path is the pathname of any file within the mounted filesystem. buf is a pointer to a statfs structure defined…

statfs, fstatfs – get filesystem statistics Synopsis#include <sys/vfs.h> /* or <sys/statfs.h> */ int statfs(const char *path, struct statfs *buf); int fstatfs(int fd, struct statfs *buf); DescriptionThe statfs() system call returns information about a mounted filesystem. path is the pathname of any file within the mounted filesystem. buf is a pointer to a statfs structure defined…

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…

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,…

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…

alloc_hugepages, free_hugepages – allocate or free huge pages Synopsisvoid *alloc_hugepages(int key, void *addr, size_t len, int prot, int flag); int free_hugepages(void *addr);DescriptionThe system calls alloc_hugepages() and free_hugepages() were introduced in Linux 2.5.36 and removed again in 2.5.54. They existed only on i386 and ia64 (when built with CONFIG_HUGETLB_PAGE). In Linux 2.4.20, the syscall numbers exist,…

flock – apply or remove an advisory lock on an open file Synopsis#include <sys/file.h> int flock(int fd, int operation); DescriptionApply or remove an advisory lock on the open file specified by fd. The argument operation is one of the following: LOCK_SH Place a shared lock. More than one process may hold a shared lock for…

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…

init_module, finit_module – load a kernel module Synopsisint init_module(void *module_image, unsigned long len, const char *param_values); int finit_module(int fd, const char *param_values, int flags);Note: glibc provides no header file declaration of init_module() and no wrapper function for finit_module(); see NOTES. Descriptioninit_module() loads an ELF image into kernel space, performs any necessary symbol relocations, initializes module…

getxattr, lgetxattr, fgetxattr – retrieve an extended attribute value Synopsis#include <sys/types.h> #include <sys/xattr.h> ssize_t getxattr(const char *path, const char *name, void *value, size_t size); ssize_t lgetxattr(const char *path, const char *name, void *value, size_t size); ssize_t fgetxattr(int fd, const char *name, void *value, size_t size);DescriptionExtended attributes are name:value pairs associated with inodes (files, directories, symbolic links, etc.). They are extensions to the normal…

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…

fsync, fdatasync – synchronize a file’s in-core state with storage device Synopsis#include <unistd.h> int fsync(int fd); int fdatasync(int fd); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): fsync():     Glibc 2.16 and later:         No feature test macros need be defined     Glibc up to and including 2.15:         _BSD_SOURCE || _XOPEN_SOURCE             || /* since glibc 2.8: */ _POSIX_C_SOURCE >= 200112L fdatasync():     _POSIX_C_SOURCE >= 199309L || _XOPEN_SOURCE >= 500 Descriptionfsync() transfers…

fcntl – manipulate file descriptor Synopsis#include <unistd.h> #include <fcntl.h> int fcntl(int fd, int cmd, … /* arg */ );Descriptionfcntl() performs one of the operations described below on the open file descriptor fd. The operation is determined by cmd. fcntl() can take an optional third argument. Whether or not this argument is required is determined by…