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accept(2) -- accept a connection on a socket
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The accept function is used with connection-based socket types (SOCK_STREAM, SOCK_SEQPACKET and SOCK_RDM). It extracts the first connection request on the queue of pending connections, creates a new c... |
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access(2) -- check user's permissions for a file
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access checks whether the process would be allowed to read, write or test for existence of the file (or other file system object) whose name is pathname. If pathname is a symbolic link permissions of ... |
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acct(2) -- switch process accounting on or off
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When called with the name of an existing file as argument, accounting is turned on, records for each terminating process are appended to filename as it terminates. An argument of NULL causes accountin... |
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adjtimex(2) -- tune kernel clock
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Linux uses David L. Mills' clock adjustment algorithm (see RFC 1305). The system call adjtimex reads and optionally sets adjustment parameters for this algorithm. It takes a pointer to a timex struct... |
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alarm(2) -- set an alarm clock for delivery of a signal
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alarm arranges for a SIGALRM signal to be delivered to the process in seconds seconds. If seconds is zero, no new alarm is scheduled. In any event any previously set alarm is cancelled. |
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bdflush(2) -- start, flush, or tune buffer-dirty-flush daemon
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bdflush starts, flushes, or tunes the buffer-dirty-flush daemon. Only the super-user may call bdflush. If func is negative or 0, and no daemon has been started, then bdflush enters the daemon code and... |
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bind(2) -- bind a name to a socket
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bind gives the socket sockfd the local address my_addr. my_addr is addrlen bytes long. Traditionally, this is called "assigning a name to a socket." When a socket is created with socket(2), it exist... |
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brk(2) -- change data segment size
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brk sets the end of the data segment to the value specified by end_data_segment, when that value is reasonable, the system does have enough memory and the process does not exceed its max data size (se... |
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cacheflush(2) -- flush contents of instruction and/or data cache
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cacheflush flushes contents of indicated cache(s) for user addresses in the range addr to (addr+nbytes-1). Cache may be one of: ICACHE Flush the instruction cache. DCACHE Write back to memory and inva... |
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capget(2) -- set/get process capabilities
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As of Linux 2.2, the power of the superuser (root) has been partitioned into a set of discrete capabilities. Every process has a set of effective capabilities identifying which capabilities (if any) i... |
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chdir(2) -- change working directory
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chdir changes the current directory to that specified in path. fchdir is identical to chdir, only that the directory is given as an open file descriptor. |
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chmod(2) -- change permissions of a file
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The mode of the file given by path or referenced by fildes is changed. Modes are specified by or'ing the following: S_ISUID 04000 set user ID on execution S_ISGID 02000 set group ID on execution S_IS... |
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chown(2) -- change ownership of a file
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The owner of the file specified by path or by fd is changed. Only the super-user may change the owner of a file. The owner of a file may change the group of the file to any group of which that owner i... |
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chroot(2) -- change root directory
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chroot changes the root directory to that specified in path. This directory will be used for path names beginning with /. The root directory is inherited by all children of the current process. Only t... |
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clone(2) -- create a child process
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clone creates a new process, just like fork(2). clone is a library function layered on top of the underlying clone system call, hereinafter referred to as sys_clone. A description of sys_clone is give... |
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close(2) -- close a file descriptor
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close closes a file descriptor, so that it no longer refers to any file and may be reused. Any locks held on the file it was associated with, and owned by the process, are removed (regardless of the f... |
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connect(2) -- initiate a connection on a socket
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The file descriptor sockfd must refer to a socket. If the socket is of type SOCK_DGRAM then the serv_addr address is the address to which datagrams are sent by default, and the only address from which... |
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create_module(2) -- create a loadable module entry
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create_module attempts to create a loadable module entry and reserve the kernel memory that will be needed to hold the module. This system call is only open to the superuser. |
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delete_module(2) -- delete a loadable module entry
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delete_module attempts to remove an unused loadable module entry. If name is NULL, all unused modules marked auto-clean will be removed. This system call is only open to the superuser. |
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dup(2) -- duplicate a file descriptor
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dup and dup2 create a copy of the file descriptor oldfd. After successful return of dup or dup2, the old and new descriptors may be used interchangeably. They share locks, file position pointers and f... |
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execve(2) -- execute program
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execve() executes the program pointed to by filename. filename must be either a binary executable, or a script starting with a line of the form "#! interpreter [arg]". In the latter case, the interp... |
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fcntl(2) -- manipulate file descriptor
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fcntl performs one of various miscellaneous operations on fd. The operation in question is determined by cmd: F_DUPFD Find the lowest numbered available file descriptor greater than or equal to arg an... |
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fdatasync(2) -- synchronize a file's in-core data with that on disk
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fdatasync flushes all data buffers of a file to disk (before the system call returns). It resembles fsync but is not required to update the metadata such as access time. Applications that access datab... |
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flock(2) -- apply or remove an advisory lock on an open file
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Apply or remove an advisory lock on an open file. The file is specified by fd. Valid operations are given below: LOCK_SH Shared lock. More than one process may hold a shared lock for a given file at a... |
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fork(2) -- create a child process
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fork creates a child process that differs from the parent process only in its PID and PPID, and in the fact that resource utilizations are set to 0. File locks and pending signals are not inherited. U... |
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fsync(2) -- synchronize a file's complete in-core state with that on disk
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fsync copies all in-core parts of a file to disk, and waits until the device reports that all parts are on stable storage. It also updates metadata stat information. It does not necessarily ensure tha... |
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getdents(2) -- get directory entries
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getdents reads several dirent structures from the directory pointed at by fd into the memory area pointed to by dirp. The parameter count is the size of the memory area. The dirent structure is declar... |
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getdomainname(2) -- get/set domain name
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These functions are used to access or to change the domain name of the current processor. If the NUL-terminated domain name requires more than len bytes, getdomainname returns the first len bytes (gli... |
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getdtablesize(2) -- get descriptor table size
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getdtablesize returns the maximum number of files a process can have open. |
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getgid(2) -- get group identity
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getgid returns the real group ID of the current process. getegid returns the effective group ID of the current process. The real ID corresponds to the ID of the calling process. The effective ID corre... |
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getgroups(2) -- get/set list of supplementary group IDs
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getgroups Up to size supplementary group IDs are returned in list. It is unspecified whether the effective group ID of the calling process is included in the returned list. (Thus, an application shoul... |
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gethostid(2) -- get or set the unique identifier of the current host
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Get or set a unique 32-bit identifier for the current machine. The 32-bit identifier is intended to be unique among all UNIX systems in existence. This normally resembles the Internet address for the ... |
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gethostname(2) -- get/set host name
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These functions are used to access or to change the host name of the current processor. |
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getitimer(2) -- get or set value of an interval timer
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The system provides each process with three interval timers, each decrementing in a distinct time domain. When any timer expires, a signal is sent to the process, and the timer (potentially) restarts.... |
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getpagesize(2) -- get system page size
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Return the number of bytes in a page. This is the system's page size, which is not necessarily the same as the hardware page size. |
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getpeername(2) -- get name of connected peer
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Getpeername returns the name of the peer connected to socket s. The namelen parameter should be initialized to indicate the amount of space pointed to by name. On return it contains the actual size of... |
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getpid(2) -- get process identification
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getpid returns the process ID of the current process. (This is often used by routines that generate unique temporary file names.) getppid returns the process ID of the parent of the current process. |
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getpriority(2) -- get/set program scheduling priority
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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. Which is one of PRIO_PROCESS, PRI... |
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getresuid(2) -- get real, effective and saved user or group ID
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getresuid and getresgid (both introduced in Linux 2.1.44) get the real, effective and saved user ID's (resp. group ID's) of the current process. |
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getrlimit(2) -- get/set resource limits and usage
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getrlimit and setrlimit get and set resource limits respectively. resource should be one of: RLIMIT_CPU /* CPU time in seconds */ RLIMIT_FSIZE /* Maximum filesize */ RLIMIT_DATA /* max data size */ RL... |
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getsid(2) -- get session ID
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getsid(0) returns the session ID of the calling process. getsid(p) returns the session ID of the process with process ID p. |
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getsockname(2) -- get socket name
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Getsockname returns the current name for the specified socket. The namelen parameter should be initialized to indicate the amount of space pointed to by name. On return it contains the actual size of ... |
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getsockopt(2) -- get and set options on sockets
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Getsockopt and setsockopt manipulate the options associated with a socket. Options may exist at multiple protocol levels; they are always present at the uppermost socket level. When manipulating socke... |
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gettimeofday(2) -- get / set time
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gettimeofday and settimeofday can get and set the time as well as a timezone. tv is a timeval struct, as specified in /usr/include/sys/time.h: struct timeval { long tv_sec; /* seconds */ long tv_usec;... |
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getuid(2) -- get user identity
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getuid returns the real user ID of the current process. geteuid returns the effective user ID of the current process. The real ID corresponds to the ID of the calling process. The effective ID corresp... |
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get_kernel_syms(2) -- retrieve exported kernel and module symbols
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If table is NULL, get_kernel_syms returns the number of symbols available for query. Otherwise it fills in a table of structures: struct kernel_sym { unsigned long value; char name[60]; }; The symbols... |
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idle(2) -- make process 0 idle
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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... |
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init_module(2) -- initialize a loadable module entry
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init_module loads the relocated module image into kernel space and runs the module's init function. The module image begins with a module structure and is followed by code and data as appropriate. Th... |
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intro(2) -- Introduction to system calls
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This chapter describes the Linux system calls. For a list of the 164 syscalls present in Linux 2.0, see syscalls(2). Calling Directly [Toc] [Back] In most cases, it is unnecessary to invoke a sy... |
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ioctl(2) -- control device
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The ioctl function manipulates the underlying device parameters of special files. In particular, many operating characteristics of character special files (e.g. terminals) may be controlled with ioctl... |
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ioctl_list(2) -- list of ioctl calls in Linux/i386 kernel
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This is Ioctl List 1.3.27, a list of ioctl calls in Linux/i386 kernel 1.3.27. It contains 421 ioctls from /usr/include/{asm,linux}/*.h. For each ioctl, I list its numerical value, its name, and its ar... |
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ioperm(2) -- set port input/output permissions
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Ioperm sets the port access permission bits for the process for num bytes starting from port address from to the value turn_on. The use of ioperm requires root privileges. Only the first 0x3ff I/O por... |
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iopl(2) -- change I/O privilege level
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iopl changes the I/O privilege level of the current process, as specified in level. This call is necessary to allow 8514-compatible X servers to run under Linux. Since these X servers require access t... |
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ipc(2) -- System V IPC system calls
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ipc() is a common kernel entry point for the System V IPC calls for messages, semaphores, and shared memory. call determines which IPC function to invoke; the other arguments are passed through to the... |
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kill(2) -- send signal to a process
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|
The kill system call can be used to send any signal to any process group or process. If pid is positive, then signal sig is sent to pid. If pid equals 0, then sig is sent to every process in the proce... |
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killpg(2) -- send signal to a process group
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Killpg sends the signal sig to the process group pgrp. See sigac- tion(2) for a list of signals. If pgrp is 0, killpg sends the signal to the sending process's process group. The sending process and ... |
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link(2) -- make a new name for a file
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link creates a new link (also known as a hard link) to an existing file. If newpath exists it will not be overwritten. This new name may be used exactly as the old one for any operation; both names re... |
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listen(2) -- listen for connections on a socket
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|
To accept connections, a socket is first created with socket(2), a willingness to accept incoming connections and a queue limit for incoming connections are specified with listen, and then the connect... |
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llseek(2) -- reposition read/write file offset
|
|
The _llseek function repositions the offset of the file descriptor fd to (offset_high<<32) | offset_low bytes relative to the beginning of the file, the current position in the file, or the end of the... |
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lseek(2) -- reposition read/write file offset
|
|
The lseek function repositions the offset of the file descriptor fildes to the argument offset according to the directive whence as follows: SEEK_SET [Toc] [Back] The offset is set to offset byt... |
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madvise(2) -- give advice about use of memory
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|
The madvise system call advises the kernel about how to handle paging input/output in the address range beginning at address start and with size length bytes. It allows an application to tell the kern... |
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mincore(2) -- get information on whether pages are in core
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|
The mincore function requests a vector describing which pages of a file are in core and can be read without disk access. The kernel will supply data for length bytes following the start address. On re... |
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mkdir(2) -- create a directory
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|
mkdir attempts to create a directory named pathname. mode specifies the permissions to use. It is modified by the process's umask in the usual way: the permissions of the created file are (mode & ~um... |
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mknod(2) -- create a special or ordinary file
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mknod attempts to create a filesystem node (file, device special file or named pipe) named pathname, specified by mode and dev. mode specifies both the permissions to use and the type of node to be cr... |
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mlock(2) -- disable paging for some parts of memory
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|
mlock disables paging for the memory in the range starting at addr with length len bytes. All pages which contain a part of the specified memory range are guaranteed be resident in RAM when the mlock ... |
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mlockall(2) -- disable paging for calling process
|
|
mlockall disables paging for all pages mapped into the address space of the calling process. This includes the pages of the code, data and stack segment, as well as shared libraries, user space kernel... |
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mmap(2) -- map or unmap files or devices into memory
|
|
The mmap function asks to map length bytes starting at offset offset from the file (or other object) specified by the file descriptor fd into memory, preferably at address start. This latter address i... |
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modify_ldt(2) -- get or set ldt
|
|
modify_ldt reads or writes the local descriptor table (ldt) for a process. The ldt is a per-process memory management table used by the i386 processor. For more information on this table, see an Intel... |
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mount(2) -- mount and unmount filesystems.
|
|
mount attaches the filesystem specified by specialfile (which is often a device name) to the directory specified by dir. umount removes the attachment of the (topmost) filesystem mounted on dir. Only ... |
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mprotect(2) -- control allowable accesses to a region of memory
|
|
mprotect controls how a section of memory may be accessed. If an access is disallowed by the protection given it, the program receives a SIGSEGV. prot is a bitwise-or of the following values: PROT_NON... |
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mremap(2) -- re-map a virtual memory address
|
|
mremap expands (or shrinks) an existing memory mapping, potentially moving it at the same time (controlled by the flags argument and the available virtual address space). old_address is the old addres... |
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msgctl(2) -- message control operations
|
|
The function performs the control operation specified by cmd on the message queue with identifier msqid. Legal values for cmd are: IPC_STAT Copy info from the message queue data structure into the str... |
|
msgget(2) -- get a message queue identifier
|
|
The function returns the message queue identifier associated to the value of the key argument. A new message queue is created if key has value IPC_PRIVATE or key isn't IPC_PRIVATE, no existing messag... |
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msgop(2) -- message operations
|
|
To send or receive a message, the calling process allocates a structure that looks like the following struct msgbuf { long mtype; /* message type, must be > 0 */ char mtext[1]; /* message data */ }; b... |
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msync(2) -- synchronize a file with a memory map
|
|
msync flushes changes made to the in-core copy of a file that was mapped into memory using mmap(2) back to disk. Without use of this call there is no guarantee that changes are written back before mun... |
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munlock(2) -- reenable paging for some parts of memory
|
|
munlock reenables paging for the memory in the range starting at addr with length len bytes. All pages which contain a part of the specified memory range can after calling munlock be moved to external... |
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munlockall(2) -- reenable paging for calling process
|
|
munlockall reenables paging for all pages mapped into the address space of the calling process. Memory locks do not stack, i.e., pages which have been locked several times by calls to mlock or mlockal... |
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nanosleep(2) -- pause execution for a specified time
|
|
nanosleep delays the execution of the program for at least the time specified in *req. The function can return earlier if a signal has been delivered to the process. In this case, it returns -1, sets ... |
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nfsservctl(2) -- syscall interface to kernel nfs daemon
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|
/* * These are the commands understood by nfsctl(). */ #define NFSCTL_SVC 0 /* This is a server process. */ #define NFSCTL_ADDCLIENT 1 /* Add an NFS client. */ #define NFSCTL_DELCLIENT 2 /* Remove an ... |
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nice(2) -- change process priority
|
|
nice adds inc to the nice value for the calling pid. (A large nice value means a low priority.) Only the superuser may specify a negative increment, or priority increase. |
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obsolete(2) -- obsolete system calls
|
|
The Linux 2.0 kernel implements these calls to support old executables. These calls return structures which have grown since their first implementation, but old executables must continue to receive ol... |
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open(2) -- open and possibly create a file or device
|
|
The open() system call is used to convert a pathname into a file descriptor (a small, non-negative integer for use in subsequent I/O as with read, write, etc.). When the call is successful, the file d... |
|
outb(2) -- port output
|
|
This family of functions is used to do low level port input and output. They are primarily designed for internal kernel use, but can be used from user space, given the following information in additio... |
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pause(2) -- wait for signal
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|
The pause library function causes the invoking process (or thread) to sleep until a signal is received that either terminates it or causes it to call a signal-catching function. |
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personality(2) -- set the process execution domain
|
|
Linux 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 sys... |
|
pipe(2) -- create pipe
|
|
pipe creates a pair of file descriptors, pointing to a pipe inode, and places them in the array pointed to by filedes. filedes[0] is for reading, filedes[1] is for writing. |
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pivot_root(2) -- change the root file system
|
|
pivot_root moves the root file system of the current process to the directory put_old and makes new_root the new root file system of the current process. The typical use of pivot_root is during system... |
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poll(2) -- wait for some event on a file descriptor
|
|
poll is a variation on the theme of select. It specifies an array of nfds structures of type struct pollfd { int fd; /* file descriptor */ short events; /* requested events */ short revents; /* return... |
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prctl(2) -- operations on a process
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|
prctl is called with a first argument describing what to do (with values defined in ), and further parameters with a significance depending on the first one. The first argument can be: ... |
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pread(2) -- read from or write to a file descriptor at a given offset
|
|
pread() reads up to count bytes from file descriptor fd at offset off- set (from the start of the file) into the buffer starting at buf. The file offset is not changed. pwrite() writes up to count byt... |
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ptrace(2) -- process trace
|
|
The ptrace system call provides a means by which a parent process may observe and control the execution of another process, and examine and change its core image and registers. It is primarily used to... |
|
query_module(2) -- query the kernel for various bits pertaining to modules.
|
|
query_module requests information related to loadable modules from the kernel. The precise nature of the information and its format depends on the which sub function. Some functions require name to na... |
|
quotactl(2) -- manipulate disk quotas
|
|
The quota system defines for each user and/or group a soft limit and a hard limit bounding the amount of disk space that can be used on a given file system. The hard limit cannot be crossed. The soft ... |
|
read(2) -- read from a file descriptor
|
|
read() attempts to read up to count bytes from file descriptor fd into the buffer starting at buf. If count is zero, read() returns zero and has no other results. If count is greater than SSIZE_MAX, t... |
|
readdir(2) -- read directory entry
|
|
This is not the function you are interested in. Look at readdir(3) for the POSIX conforming C library interface. This page documents the bare kernel system call interface, which can change, and which ... |
|
readlink(2) -- read value of a symbolic link
|
|
readlink places the contents of the symbolic link path in the buffer buf, which has size bufsiz. readlink does not append a NUL character to buf. It will truncate the contents (to a length of bufsiz c... |
|
readv(2) -- read or write a vector
|
|
readv reads data from file descriptor fd, and puts the result in the buffers described by vector. The number of buffers is specified by count. The buffers are filled in the order specified. Operates j... |
|
reboot(2) -- reboot or enable/disable Ctrl-Alt-Del
|
|
The reboot call reboots the system, or enables/disables the reboot keystroke (abbreviated CAD, since the default is Ctrl-Alt-Delete; it can be changed using loadkeys(1)). This system call will fail (w... |
|
recv(2) -- receive a message from a socket
|
|
The recvfrom and recvmsg calls are used to receive messages from a socket, and may be used to receive data on a socket whether or not it is connection-oriented. If from is not NULL, and the socket is ... |
|
rename(2) -- change the name or location of a file
|
|
rename renames a file, moving it between directories if required. Any other hard links to the file (as created using link(2)) are unaffected. If newpath already exists it will be atomically replaced (... |
|
rmdir(2) -- delete a directory
|
|
rmdir deletes a directory, which must be empty. |
|
sched_get_priority_max(2) -- get static priority range
|
|
sched_get_priority_max returns the maximum priority value that can be used with the scheduling algorithm identified by policy. sched_get_priority_min returns the minimum priority value that can be use... |
|
sched_rr_get_interval(2) -- get the SCHED_RR interval for the named process
|
|
sched_rr_get_interval writes into the timespec structure pointed to by tp the round robin time quantum for the process identified by pid. If pid is zero, the time quantum for the calling process is wr... |
|
sched_setparam(2) -- set and get scheduling parameters
|
|
sched_setparam sets the scheduling parameters associated with the scheduling policy for the process identified by pid. If pid is zero, then the parameters of the current process are set. The interpret... |
|
sched_setscheduler(2) -- set and get scheduling algorithm/parameters
|
|
sched_setscheduler sets both the scheduling policy and the associated parameters for the process identified by pid. If pid equals zero, the scheduler of the calling process will be set. The interpreta... |
|
sched_yield(2) -- yield the processor
|
|
A process can relinquish the processor voluntarily without blocking by calling sched_yield. The process will then be moved to the end of the queue for its static priority and a new process gets to run... |
|
select(2) -- synchronous I/O multiplexing
|
|
The functions select and pselect wait for a number of file descriptors to change status. Their function is identical, with three differences: (i) The select function uses a timeout that is a struct ti... |
|
semctl(2) -- semaphore control operations
|
|
The function performs the control operation specified by cmd on the semaphore set (or on the semnum-th semaphore of the set) identified by semid. The first semaphore of the set is indicated by a value... |
|
semget(2) -- get a semaphore set identifier
|
|
The function returns the semaphore set identifier associated to the value of the argument key. A new set of nsems semaphores is created if key has value IPC_PRIVATE or key isn't IPC_PRIVATE, no exist... |
|
semop(2) -- semaphore operations
|
|
The function performs operations on selected members of the semaphore set indicated by semid. Each of the nsops elements in the array pointed to by sops specify an operation to be performed on a semap... |
|
send(2) -- send a message from a socket
|
|
Send, sendto, and sendmsg are used to transmit a message to another socket. Send may be used only when the socket is in a connected state, while sendto and sendmsg may be used at any time. The address... |
|
sendfile(2) -- transfer data between file descriptors
|
|
This call copies data between one file descriptor and another. Either or both of these file descriptors may refer to a socket (but see below). in_fd should be a file descriptor opened for reading and ... |
|
seteuid(2) -- set effective user or group ID
|
|
seteuid sets the effective user ID of the current process. Unprivileged user processes may only set the effective user ID to the real user ID, the effective user ID or the saved user ID. Precisely the... |
|
setfsgid(2) -- set group identity used for file system checks
|
|
setfsgid sets the group ID that the Linux kernel uses to check for all accesses to the file system. Normally, the value of fsgid will shadow the value of the effective group ID. In fact, whenever the ... |
|
setfsuid(2) -- set user identity used for file system checks
|
|
setfsuid sets the user ID that the Linux kernel uses to check for all accesses to the file system. Normally, the value of fsuid will shadow the value of the effective user ID. In fact, whenever the ef... |
|
setgid(2) -- set group identity
|
|
setgid sets the effective group ID of the current process. If the caller is the superuser, the real and saved group ID's are also set. Under Linux, setgid is implemented like the POSIX version with t... |
|
setpgid(2) -- set/get process group
|
|
setpgid sets the process group ID of the process specified by pid to pgid. If pid is zero, the process ID of the current process is used. If pgid is zero, the process ID of the process specified by pi... |
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setresuid(2) -- set real, effective and saved user or group ID
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setresuid (introduced in Linux 2.1.44) sets the real user ID, the effective user ID, and the saved set-user-ID of the current process. Unprivileged user processes (i.e., processes with each of real, e... |
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setreuid(2) -- set real and/or effective user or group ID
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setreuid sets real and effective user IDs of the current process. Unprivileged users may only set the real user ID to the real user ID or the effective user ID, and may only set the effective user ID ... |
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setsid(2) -- creates a session and sets the process group ID
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setsid() creates a new session if the calling process is not a process group leader. The calling process is the leader of the new session, the process group leader of the new process group, and has no... |
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setuid(2) -- set user identity
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setuid sets the effective user ID of the current process. If the effective userid of the caller is root, the real and saved user ID's are also set. Under Linux, setuid is implemented like the POSIX v... |
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setup(2) -- setup devices and file systems, mount root file system
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setup is called once from within linux/init/main.c. It calls initialization functions for devices and file systems configured into the kernel and then mounts the root file system. No user process may ... |
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shmctl(2) -- shared memory control
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shmctl() allows the user to receive information on a shared memory segment, set the owner, group, and permissions of a shared memory segment, or destroy a segment. The information about the segment id... |
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shmget(2) -- allocates a shared memory segment
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shmget() returns the identifier of the shared memory segment associated to the value of the argument key. A new shared memory segment, with size equal to the round up of size to a multiple of PAGE_SIZ... |
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shmop(2) -- shared memory operations
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The function shmat attaches the shared memory segment identified by shmid to the data segment of the calling process. The attaching address is specified by shmaddr with one of the following criteria: ... |
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shutdown(2) -- shut down part of a full-duplex connection
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The shutdown call causes all or part of a full-duplex connection on the socket associated with s to be shut down. If how is 0, further receives will be disallowed. If how is 1, further sends will be d... |
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sigaction(2) -- POSIX signal handling functions.
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The sigaction system call is used to change the action taken by a process on receipt of a specific signal. signum specifies the signal and can be any valid signal except SIGKILL and SIGSTOP. If act is... |
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sigblock(2) -- manipulate the signal mask
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This interface is made obsolete by sigprocmask(2). The sigblock system call adds the signals specified in mask to the set of signals currently being blocked from delivery. The sigsetmask system call r... |
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signal(2) -- ANSI C signal handling
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The signal() system call installs a new signal handler for the signal with number signum. The signal handler is set to sighandler which may be a user specified function, or either SIG_IGN or SIG_DFL. ... |
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sigpause(2) -- atomically release blocked signals and wait for interrupt
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This interface is made obsolete by sigsuspend(2). sigpause assigns sigmask to the set of masked signals and then waits for a signal to arrive; on return the set of masked signals is restored. sigmask ... |
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sigreturn(2) -- return from signal handler and cleanup stack frame
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When the Linux kernel creates the stack frame for a signal handler, a call to sigreturn is inserted into the stack frame so that the the signal handler will call sigreturn upon return. This inserted c... |
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sigvec(2) -- BSD software signal facilities
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This interface is made obsolete by sigaction(2). Under Linux sigvec is #define'd to sigaction, and provides at best a rough approximation of the BSD sigvec interface. |
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socket(2) -- create an endpoint for communication
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Socket creates an endpoint for communication and returns a descriptor. The domain parameter specifies a communication domain; this selects the protocol family which will be used for communication. The... |
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socketcall(2) -- socket system calls
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socketcall is a common kernel entry point for the socket system calls. call determines which socket function to invoke. args points to a block containing the actual arguments, which are passed through... |
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socketpair(2) -- create a pair of connected sockets
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The call creates an unnamed pair of connected sockets in the specified domain d, of the specified type, and using the optionally specified protocol. The descriptors used in referencing the new sockets... |
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stat(2) -- get file status
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These functions return information about the specified file. You do not need any access rights to the file to get this information but you need search rights to all directories named in the path leadi... |
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statfs(2) -- get file system statistics
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statfs returns information about a mounted file system. path is the path name of any file within the mounted filesystem. buf is a pointer to a statfs structure defined as follows: struct statfs { long... |
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stime(2) -- set time
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stime sets the system's idea of the time and date. Time, pointed to by t, is measured in seconds from 00:00:00 GMT January 1, 1970. stime() may only be executed by the super user. |
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swapon(2) -- start/stop swapping to file/device
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swapon sets the swap area to the file or block device specified by path. swapoff stops swapping to the file or block device specified by path. swapon takes a swapflags argument. If swapflags has the S... |
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symlink(2) -- make a new name for a file
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symlink creates a symbolic link named newpath which contains the string oldpath. Symbolic links are interpreted at run-time as if the contents of the link had been substituted into the path being foll... |
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sync(2) -- commit buffer cache to disk.
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sync first commits inodes to buffers, and then buffers to disk. |
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syscalls(2) -- list of all system calls
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As of Linux 2.0.34, there are 164 system calls listed in /usr/include/asm/unistd.h. This man page lists them. _llseek(2), _newselect(2), _sysctl(2), access(2), acct(2), adjtimex(2), afs_syscall, alarm... |
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sysctl(2) -- read/write system parameters
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The _sysctl call reads and/or writes kernel parameters. For example, the hostname, or the maximum number of open files. The argument has the form struct __sysctl_args { int *name; /* integer vector de... |
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sysfs(2) -- get file system type information
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sysfs returns information about the file system types currently present in the kernel. The specific form of the sysfs call and the information returned depends on the option in effect: 1 Translate the... |
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sysinfo(2) -- returns information on overall system statistics
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Until Linux 2.3.16, sysinfo used to return information in the following structure: struct sysinfo { long uptime; /* Seconds since boot */ unsigned long loads[3]; /* 1, 5, and 15 minute load averages *... |
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syslog(2) -- read and/or clear kernel message ring buffer; set console_loglevel
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This is probably not the function you are interested in. Look at sys- log(3) for the C library interface. This page only documents the bare kernel system call interface. The type argument determines t... |
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time(2) -- get time in seconds
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time returns the time since the Epoch (00:00:00 UTC, January 1, 1970), measured in seconds. If t is non-NULL, the return value is also stored in the memory pointed to by t. |
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times(2) -- get process times
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The times() function stores the current process times in the struct tms that buf points to. The struct tms is as defined in : struct tms { clock_t tms_utime; /* user time */ clock_t tms_s... |
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truncate(2) -- truncate a file to a specified length
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Truncate causes the file named by path or referenced by fd to be truncated to at most length bytes in size. If the file previously was larger than this size, the extra data is lost. If the file previo... |
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umask(2) -- set file creation mask
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umask sets the umask to mask & 0777. The umask is used by open(2) to set initial file permissions on a newly-created file. Specifically, permissions in the umask are turned off from the mode argument ... |
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uname(2) -- get name and information about current kernel
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uname returns system information in the structure pointed to by buf. The utsname struct is as defined in : struct utsname { char sysname[SYS_NMLN]; char nodename[SYS_NMLN]; char release... |
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unimplemented(2) -- unimplemented system calls
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These system calls are not implemented in the Linux 2.0 kernel. |
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unlink(2) -- delete a name and possibly the file it refers to
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unlink deletes a name from the filesystem. If that name was the last link to a file and no processes have the file open the file is deleted and the space it was using is made available for reuse. If t... |
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uselib(2) -- select shared library
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uselib selects the shared library binary that will be used by the calling process. |
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ustat(2) -- get file system statistics
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ustat returns information about a mounted file system. dev is a device number identifying a device containing a mounted file system. ubuf is a pointer to a ustat structure that contains the following ... |
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utime(2) -- change access and/or modification times of an inode
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utime changes the access and modification times of the inode specified by filename to the actime and modtime fields of buf respectively. If buf is NULL, then the access and modification times of the f... |
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vfork(2) -- create a child process and block parent
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vhangup(2) -- virtually hangup the current tty
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vhangup simulates a hangup on the current terminal. This call arranges for other users to have a "clean" tty at login time. |
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vm86(2) -- enter virtual 8086 mode
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The system call vm86 was introduced in Linux 0.97p2. In Linux 2.1.15 and 2.0.28 it was renamed to vm86old, and a new vm86 was introduced. The definition of `struct vm86_struct' was changed in 1.1.8 a... |
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wait(2) -- wait for process termination
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The wait function suspends execution of the current process until a child has exited, or until a signal is delivered whose action is to terminate the current process or to call a signal handling funct... |
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wait4(2) -- wait for process termination, BSD style
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The wait3 function suspends execution of the current process until a child has exited, or until a signal is delivered whose action is to terminate the current process or to call a signal handling func... |
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write(2) -- write to a file descriptor
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write writes up to count bytes to the file referenced by the file descriptor fd from the buffer starting at buf. POSIX requires that a read() which can be proved to occur after a write() has returned ... |
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_exit(2) -- terminate the current process
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_exit terminates the calling process immediately. Any open file descriptors belonging to the process are closed; any children of the process are inherited by process 1, init, and the process's parent... |
