Section 2: system calls
NAME setfsuid – set user identity used for filesystem checks SYNOPSIS #include <sys/fsuid.h> int setfsuid(uid_t fsuid); DESCRIPTION On Linux, a process has both a filesystem user ID and an effective user ID. The (Linux-specific) filesystem user ID is used for permissions checking when accessing filesystem objects, while the effective user ID is used for various…
NAME setfsuid – set user identity used for filesystem checks SYNOPSIS #include <sys/fsuid.h> int setfsuid(uid_t fsuid); DESCRIPTION On Linux, a process has both a filesystem user ID and an effective user ID. The (Linux-specific) filesystem user ID is used for permissions checking when accessing filesystem objects, while the effective user ID is used for various…
NAME setfsgid – set group identity used for filesystem checks SYNOPSIS #include <sys/fsuid.h> int setfsgid(uid_t fsgid); DESCRIPTION On Linux, a process has both a filesystem group ID and an effective group ID. The (Linux-specific) filesystem group ID is used for permissions checking when accessing filesystem objects, while the effective group ID is used for some…
NAME setfsgid – set group identity used for filesystem checks SYNOPSIS #include <sys/fsuid.h> int setfsgid(uid_t fsgid); DESCRIPTION On Linux, a process has both a filesystem group ID and an effective group ID. The (Linux-specific) filesystem group ID is used for permissions checking when accessing filesystem objects, while the effective group ID is used for some…
NAME seteuid, setegid – set effective user or group ID SYNOPSIS #include <sys/types.h> #include <unistd.h> int seteuid(uid_t euid); int setegid(gid_t egid); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): seteuid(), setegid(): _POSIX_C_SOURCE >= 200112L || /* Glibc versions <= 2.19: */ _BSD_SOURCE DESCRIPTION seteuid() sets the effective user ID of the calling process. Unprivileged processes may only set the effective user ID to…
NAME seteuid, setegid – set effective user or group ID SYNOPSIS #include <sys/types.h> #include <unistd.h> int seteuid(uid_t euid); int setegid(gid_t egid); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): seteuid(), setegid(): _POSIX_C_SOURCE >= 200112L || /* Glibc versions <= 2.19: */ _BSD_SOURCE DESCRIPTION seteuid() sets the effective user ID of the calling process. Unprivileged processes may only set the effective user ID to…
NAME getdomainname, setdomainname – get/set NIS domain name SYNOPSIS #include <unistd.h> int getdomainname(char *name, size_t len); int setdomainname(const char *name, size_t len); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): getdomainname(), setdomainname(): Since glibc 2.21 : _DEFAULT_SOURCE In glibc 2.19 and 2.20 : _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE & nbsp; < 500) Up to…
NAME getcontext, setcontext – get or set the user context SYNOPSIS #include <ucontext.h> int getcontext(ucontext_t *ucp); int setcontext(const ucontext_t *ucp); DESCRIPTION In a System V-like environment, one has the two types mcontext_t and ucontext_t defined in <ucontext.h> and the four functions getcontext(), setcontext(), makecontext(3), and swapcontext(3) that allow user-level context switching between multiple threads of…
NAME set_tid_address – set pointer to thread ID SYNOPSIS #include <linux/unistd.h> pid_t set_tid_address(int *tidptr); Note: There is no glibc wrapper for this system call; see NOTES. DESCRIPTION For each thread, the kernel maintains two attributes (addresses) called set_child_tid and clear_child_tid. These two attributes contain the value NULL by default. set_child_tid If a thread is started…
NAME get_thread_area, set_thread_area – manipulate thread-local storage information SYNOPSIS #include <linux/unistd.h> #if defined __i386__ || defined __x86_64__ #include <asm/ldt.h> int get_thread_area(struct user_desc *u_info); int set_thread_area(struct user_desc *u_info); #elif defined __m68k__ int get_thread_area(void); int set_thread_area(unsigned long tp); #elif defined __mips__ int set_thread_area(unsigned long addr); #endif Note: There are no glibc wrappers for these system calls; see…
NAME get_robust_list, set_robust_list – get/set list of robust futexes SYNOPSIS #include <linux/futex.h> #include <sys/types.h> #include <syscall.h> long get_robust_list(int pid, struct robust_list_head **head_ptr, size_t *len_ptr); long set_robust_list(struct robust_list_head *head, size_t len); Note: There are no glibc wrappers for these system calls; see NOTES. DESCRIPTION These system calls deal with per-thread robust futex lists. These lists are…
NAME set_mempolicy – set default NUMA memory policy for a thread and its children SYNOPSIS #include <numaif.h> long set_mempolicy(int mode, const unsigned long *nodemask, unsigned long maxnode); Link with – lnuma. DESCRIPTION set_mempolicy() sets the NUMA memory policy of the calling thread, which consists of a policy mode and zero or more nodes, to the…
NAME send, sendto, sendmsg – send a message on a socket SYNOPSIS #include <sys/socket.h> #include <sys/types.h> ssize_t send(int sockfd, const void *buf, size_t len, int flags); ssize_t sendto(int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *dest_addr, socklen_t addrlen); ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags); DESCRIPTION The system calls…
NAME send, sendto, sendmsg – send a message on a socket SYNOPSIS #include <sys/socket.h> #include <sys/types.h> ssize_t send(int sockfd, const void *buf, size_t len, int flags); ssize_t sendto(int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *dest_addr, socklen_t addrlen); ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags); DESCRIPTION The system calls…
NAME sendmmsg – send multiple messages on a socket SYNOPSIS #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <sys/socket.h> int sendmmsg(int sockfd, struct mmsghdr *msgvec, unsigned int vlen, int flags); DESCRIPTION The sendmmsg() system call is an extension of sendmsg(2) that allows the caller to transmit multiple messages on a socket using a single system call….
NAME sendfile – transfer data between file descriptors SYNOPSIS #include <sys/sendfile.h> ssize_t sendfile(int out_fd, int in_fd, off_t *offset, size_t count); DESCRIPTION sendfile() copies data between one file descriptor and another. Because this copying is done within the kernel, sendfile() is more efficient than the combination of read(2) and write(2), which would require transferring data to…
NAME sendfile – transfer data between file descriptors SYNOPSIS #include <sys/sendfile.h> ssize_t sendfile(int out_fd, int in_fd, off_t *offset, size_t count); DESCRIPTION sendfile() copies data between one file descriptor and another. Because this copying is done within the kernel, sendfile() is more efficient than the combination of read(2) and write(2), which would require transferring data to…
NAME send, sendto, sendmsg – send a message on a socket SYNOPSIS #include <sys/socket.h> #include <sys/types.h> ssize_t send(int sockfd, const void *buf, size_t len, int flags); ssize_t sendto(int sockfd, const void *buf, size_t len, int flags, const struct sockaddr *dest_addr, socklen_t addrlen); ssize_t sendmsg(int sockfd, const struct msghdr *msg, int flags); DESCRIPTION The system calls…
NAME semop, semtimedop – System V semaphore operations SYNOPSIS #include <sys/ipc.h> #include <sys/sem.h> #include <sys/types.h> int semop(int semid, struct sembuf *sops, size_t nsops); int semtimedop(int semid, struct sembuf *sops, size_t nsops, const struct timespec *timeout); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): semtimedop(): _GNU_SOURCE DESCRIPTION Each semaphore in a System V semaphore set has…
NAME semop, semtimedop – System V semaphore operations SYNOPSIS #include <sys/ipc.h> #include <sys/sem.h> #include <sys/types.h> int semop(int semid, struct sembuf *sops, size_t nsops); int semtimedop(int semid, struct sembuf *sops, size_t nsops, const struct timespec *timeout); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): semtimedop(): _GNU_SOURCE DESCRIPTION Each semaphore in a System V semaphore set has…