The Linux Manuals (man pages) document is an important part of Linux documents. Linux Manuals are organized as several sections. Each section has a group of commands for a specific area in Linux usage, administration or development.
NAME idle – make process 0 idle SYNOPSIS #include <unistd.h> int idle(void); DESCRIPTION idle() is an internal system call used during bootstrap. It marks the process’s pages as swappable, lowers its priority, and enters the main scheduling loop. idle() never returns. Only process 0 may call idle(). Any user process, even a process with superuser…
NAME 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 SYNOPSIS Unimplemented system calls. DESCRIPTION These system calls are not implemented in the Linux kernel. RETURN VALUE These system calls always return -1 and set errno to ENOSYS. NOTES…
NAME 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);…
NAME getunwind – copy the unwind data to caller’s buffer SYNOPSIS #include <linux/unwind.h> #include <syscall.h> long getunwind(void *buf, size_t buf_size); Note: There is no glibc wrapper for this system call; see NOTES. DESCRIPTION Note: this function is obsolete. The IA-64-specific getunwind() system call copies the kernel’s call frame unwind data into the buffer pointed to…
NAME getuid, geteuid – get user identity SYNOPSIS #include <unistd.h> #include <sys/types.h> uid_t getuid(void); uid_t geteuid(void); DESCRIPTION getuid() returns the real user ID of the calling process. geteuid() returns the effective user ID of the calling process. ERRORS These functions are always successful. CONFORMING TO POSIX.1-2001, POSIX.1-2008, 4.3BSD. NOTES History In UNIX V6 the getuid()…
NAME getuid, geteuid – get user identity SYNOPSIS #include <unistd.h> #include <sys/types.h> uid_t getuid(void); uid_t geteuid(void); DESCRIPTION getuid() returns the real user ID of the calling process. geteuid() returns the effective user ID of the calling process. ERRORS These functions are always successful. CONFORMING TO POSIX.1-2001, POSIX.1-2008, 4.3BSD. NOTES History In UNIX V6 the getuid()…
NAME gettimeofday, settimeofday – get / set time SYNOPSIS #include <sys/time.h> int gettimeofday(struct timeval *tv, struct timezone *tz); int settimeofday(const struct timeval *tv, const struct timezone *tz); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): settimeofday(): Since glibc 2.19: _DEFAULT_SOURCE Glibc 2.19 and earlier: _BSD_SOURCE DESCRIPTION The functions gettimeofday() and settimeofday() can get and set…
NAME gettid – get thread identification SYNOPSIS #define _GNU_SOURCE #include <sys/types.h> #include <unistd.h> pid_t gettid(void); DESCRIPTION gettid() returns the caller’s thread ID (TID). In a single-threaded process, the thread ID is equal to the process ID (PID, as returned by getpid(2)). In a multithreaded process, all threads have the same PID, but each one has…
NAME getsockopt, setsockopt – get and set options on sockets SYNOPSIS #include <sys/socket.h> #include <sys/types.h> /* See NOTES */ int getsockopt(int sockfd, int level, int optname, void *optval, socklen_t *optlen); int setsockopt(int sockfd, int level, int optname, const void *optval, socklen_t optlen); DESCRIPTION getsockopt() and setsockopt() manipulate options for the socket referred to by the…
NAME getsockname – get socket name SYNOPSIS #include <sys/socket.h> int getsockname(int sockfd, struct sockaddr *addr, socklen_t *addrlen); DESCRIPTION getsockname() returns the current address to which the socket sockfd is bound, in the buffer pointed to by addr. The addrlen argument should be initialized to indicate the amount of space (in bytes) pointed to by addr….
NAME getsid – get session ID SYNOPSIS #include <sys/types.h> #include <unistd.h> pid_t getsid(pid_t pid); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): getsid(): _XOPEN_SOURCE >= 500 || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L DESCRIPTION getsid(0) returns the session ID of the calling process. getsid() returns the session ID of the process with process ID pid. If pid is 0, getsid() returns…
NAME getrusage – get resource usage SYNOPSIS #include <sys/time.h> #include <sys/resource.h> int getrusage(int who, struct rusage *usage); DESCRIPTION getrusage() returns resource usage measures for who, which can be one of the following: RUSAGE_SELF Return resource usage statistics for the calling process, which is the sum of resources used by all threads in the process. RUSAGE_CHILDREN…
NAME getrlimit, setrlimit, prlimit – get/set resource limits SYNOPSIS #include <sys/time.h> #include <sys/resource.h> int getrlimit(int resource, struct rlimit *rlim); int setrlimit(int resource, const struct rlimit *rlim); int prlimit(pid_t pid, int resource, const struct rlimit *new_limit, struct rlimit *old_limit); Feature Test Macro Requirements for glibc (see feature_test_macros(7)): prlimit(): _GNU_SOURCE DESCRIPTION The getrlimit() and setrlimit() system calls…
NAME getresuid, getresgid – get real, effective and saved user/group IDs SYNOPSIS #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <unistd.h> int getresuid(uid_t *ruid, uid_t *euid, uid_t *suid); int getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid); DESCRIPTION getresuid() returns the real UID, the effective UID, and the saved set-user-ID of the calling process, in the arguments ruid,…
NAME getresuid, getresgid – get real, effective and saved user/group IDs SYNOPSIS #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <unistd.h> int getresuid(uid_t *ruid, uid_t *euid, uid_t *suid); int getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid); DESCRIPTION getresuid() returns the real UID, the effective UID, and the saved set-user-ID of the calling process, in the arguments ruid,…
NAME getresuid, getresgid – get real, effective and saved user/group IDs SYNOPSIS #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <unistd.h> int getresuid(uid_t *ruid, uid_t *euid, uid_t *suid); int getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid); DESCRIPTION getresuid() returns the real UID, the effective UID, and the saved set-user-ID of the calling process, in the arguments ruid,…
NAME getresuid, getresgid – get real, effective and saved user/group IDs SYNOPSIS #define _GNU_SOURCE /* See feature_test_macros(7) */ #include <unistd.h> int getresuid(uid_t *ruid, uid_t *euid, uid_t *suid); int getresgid(gid_t *rgid, gid_t *egid, gid_t *sgid); DESCRIPTION getresuid() returns the real UID, the effective UID, and the saved set-user-ID of the calling process, in the arguments ruid,…
NAME getrandom – obtain a series of random bytes SYNOPSIS #include <sys/random.h> ssize_t getrandom(void *buf, size_t buflen, unsigned int flags); DESCRIPTION The getrandom() system call fills the buffer pointed to by buf with up to buflen random bytes. These bytes can be used to seed user-space random number generators or for cryptographic purposes. By default,…
NAME getpriority, setpriority – get/set program scheduling priority SYNOPSIS #include <sys/time.h> #include <sys/resource.h> int getpriority(int which, id_t who); int setpriority(int which, id_t who, int prio); DESCRIPTION The scheduling priority of the process, process group, or user, as indicated by which and who is obtained with the getpriority() call and set with the setpriority() call. The…
NAME getpid, getppid – get process identification SYNOPSIS #include <sys/types.h> #include <unistd.h> pid_t getpid(void); pid_t getppid(void); DESCRIPTION getpid() returns the process ID (PID) of the calling process. (This is often used by routines that generate unique temporary filenames.) getppid() returns the process ID of the parent of the calling process. This will be either the…