pread, pwrite – read from or write to a file descriptor at a given offset Synopsis#include <unistd.h> ssize_t pread(int fd, void *buf, size_t count, off_t offset); ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): pread(), pwrite(): _XOPEN_SOURCE >= 500 || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809LDescriptionpread() reads…
pread, pwrite – read from or write to a file descriptor at a given offset Synopsis#include <unistd.h> ssize_t pread(int fd, void *buf, size_t count, off_t offset); ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): pread(), pwrite(): _XOPEN_SOURCE >= 500 || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809LDescriptionpread() reads…
prctl – operations on a process or thread Synopsis#include <sys/prctl.h> int prctl(int option, unsigned long arg2, unsigned long arg3, unsigned long arg4, unsigned long arg5);Descriptionprctl() manipulates various aspects of the behavior of the calling thread or process. Note that careless use of some prctl() operations can confuse the user-space run-time environment, so these operations should…
poll, ppoll – wait for some event on a file descriptor Synopsis#include <poll.h> int poll(struct pollfd *fds, nfds_t nfds, int timeout); #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <signal.h> #include <poll.h> int ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *tmo_p, const sigset_t *sigmask);Descriptionpoll() performs a similar task to select(2): it waits for one of…
posix_fadvise – predeclare an access pattern for file data Synopsis#include <fcntl.h> int posix_fadvise(int fd, off_t offset, off_t len, int advice);Feature Test Macro Requirements for glibc (see feature_test_macros(7)): posix_fadvise(): _POSIX_C_SOURCE >= 200112LDescriptionPrograms can use posix_fadvise() to announce an intention to access file data in a specific pattern in the future, thus allowing the kernel to perform appropriate optimizations….
poll, ppoll – wait for some event on a file descriptor Synopsis#include <poll.h> int poll(struct pollfd *fds, nfds_t nfds, int timeout); #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <signal.h> #include <poll.h> int ppoll(struct pollfd *fds, nfds_t nfds, const struct timespec *tmo_p, const sigset_t *sigmask);Descriptionpoll() performs a similar task to select(2): it waits for one of…
mprotect, pkey_mprotect – set protection on a region of memory Synopsis#include <sys/mman.h> int mprotect(void *addr, size_t len, int prot); #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <sys/mman.h> int pkey_mprotect(void *addr, size_t len, int prot, int pkey);Descriptionmprotect() changes the access protections for the calling process’s memory pages containing any part of the address range in the…
pkey_alloc, pkey_free – allocate or free a protection key Synopsis#define _GNU_SOURCE /* See feature_test_macros(7) */ #include <sys/mman.h> int pkey_alloc(unsigned int flags, unsigned int access_rights); int pkey_free(int pkey);Descriptionpkey_alloc() allocates a protection key (pkey) and allows it to be passed to pkey_mprotect(2). The pkey_alloc() flags is reserved for future use and currently must always be specified as…
pkey_alloc, pkey_free – allocate or free a protection key Synopsis#define _GNU_SOURCE /* See feature_test_macros(7) */ #include <sys/mman.h> int pkey_alloc(unsigned int flags, unsigned int access_rights); int pkey_free(int pkey);Descriptionpkey_alloc() allocates a protection key (pkey) and allows it to be passed to pkey_mprotect(2). The pkey_alloc() flags is reserved for future use and currently must always be specified as…
pivot_root – change the root mount Synopsisint pivot_root(const char *new_root, const char *put_old); Note: There is no glibc wrapper for this system call; see NOTES. Descriptionpivot_root() changes the root mount in the mount namespace of the calling process. More precisely, it moves the root mount to the directory put_old and makes new_root the new root…
pipe, pipe2 – create pipe Synopsis#include <unistd.h> /* On Alpha, IA-64, MIPS, SuperH, and SPARC/SPARC64; see NOTES */ struct fd_pair { long fd[2]; }; struct fd_pair pipe(); /* On all other architectures */ int pipe(int pipefd[2]); #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <fcntl.h> /* Obtain O_* constant definitions */ #include <unistd.h> int pipe2(int pipefd[2],…
pidfd_send_signal – send a signal to a process specified by a file descriptor Synopsis#include <signal.h> int pidfd_send_signal(int pidfd, int sig, siginfo_t *info, unsigned int flags);DescriptionThe pidfd_send_signal() system call sends the signal sig to the target process referred to by pidfd, a PID file descriptor that refers to a process. If the info argument points to…
pidfd_open – obtain a file descriptor that refers to a process Synopsis#include <sys/types.h> int pidfd_open(pid_t pid, unsigned int flags);DescriptionThe pidfd_open() system call creates a file descriptor that refers to the process whose PID is specified in pid. The file descriptor is returned as the function result; the close-on-exec flag is set on the file descriptor….
pidfd_getfd – obtain a duplicate of another process’s file descriptor Synopsisint pidfd_getfd(int pidfd, int targetfd, unsigned int flags);DescriptionThe pidfd_getfd() system call allocates a new file descriptor in the calling process. This new file descriptor is a duplicate of an existing file descriptor, targetfd, in the process referred to by the PID file descriptor pidfd. The…
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…
personality – set the process execution domain Synopsis#include <sys/personality.h> int personality(unsigned long persona); DescriptionLinux supports different execution domains, or personalities, for each process. Among other things, execution domains tell Linux how to map signal numbers into signal actions. The execution domain system allows Linux to provide limited support for binaries compiled under other UNIX-like operating…
perfmonctl – interface to IA-64 performance monitoring unit Synopsis#include <syscall.h> #include <perfmon.h> long perfmonctl(int fd, int cmd, void *arg, int narg);Note: There is no glibc wrapper for this system call; see NOTES. DescriptionThe IA-64-specific perfmonctl() system call provides an interface to the PMU (performance monitoring unit). The PMU consists of PMD (performance monitoring data) registers…
perf_event_open – set up performance monitoring Synopsis#include <linux/perf_event.h> #include <linux/hw_breakpoint.h> int perf_event_open(struct perf_event_attr *attr, pid_t pid, int cpu, int group_fd, unsigned long flags);Note: There is no glibc wrapper for this system call; see NOTES. DescriptionGiven a list of parameters, perf_event_open() returns a file descriptor, for use in subsequent system calls (read(2), mmap(2), prctl(2), fcntl(2), etc.)….
pciconfig_read, pciconfig_write, pciconfig_iobase – pci device information handling Synopsis#include <pci.h> int pciconfig_read(unsigned long bus, unsigned long dfn, unsigned long off, unsigned long len, void *buf); int pciconfig_write(unsigned long bus, unsigned long dfn, unsigned long off, unsigned long len, void *buf); int pciconfig_iobase(long which, unsigned long bus, unsigned long devfn);DescriptionMost of the interaction with PCI devices…
pciconfig_read, pciconfig_write, pciconfig_iobase – pci device information handling Synopsis#include <pci.h> int pciconfig_read(unsigned long bus, unsigned long dfn, unsigned long off, unsigned long len, void *buf); int pciconfig_write(unsigned long bus, unsigned long dfn, unsigned long off, unsigned long len, void *buf); int pciconfig_iobase(long which, unsigned long bus, unsigned long devfn);DescriptionMost of the interaction with PCI devices…