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Annotation of cci/usr/src/man/man2/intro.2, revision 1.1

1.1     ! root        1: .TH INTRO 2
        !             2: .de {n
        !             3: .HP
        !             4: \\$1  \\$2  \\$3
        !             5: .br
        !             6: ..
        !             7: .SH NAME
        !             8: intro \- introduction to system calls and error numbers
        !             9: .SH SYNOPSIS
        !            10: .B #include \|<errno.h>
        !            11: .SH DESCRIPTION
        !            12: This section
        !            13: describes all of the system calls.
        !            14: Most of these calls have one or more error returns.
        !            15: An error condition is indicated by an otherwise
        !            16: impossible returned value.
        !            17: This is almost always \-1;
        !            18: the individual descriptions specify the details.
        !            19: An error number is also made available
        !            20: in the external variable
        !            21: .IR errno .
        !            22: .I Errno\^
        !            23: is not cleared on successful calls, so it should be tested only
        !            24: after an error has been indicated.
        !            25: .PP
        !            26: Each system call description attempts to
        !            27: list all possible error numbers.
        !            28: The following is a complete list of the error numbers and
        !            29: their names as defined in
        !            30: .BR <errno.h> .
        !            31: .{n 1 \s-1EPERM\s+1 "Not owner"
        !            32: Typically this error indicates
        !            33: an attempt to modify a file in some way forbidden
        !            34: except to its owner or super-user.
        !            35: It is also returned for attempts
        !            36: by ordinary users to do things
        !            37: allowed only to the super-user.
        !            38: .{n 2 \s-1ENOENT\s+1 "No such file or directory"
        !            39: This error occurs when a file name is specified
        !            40: and the file should exist but doesn't, or when one
        !            41: of the directories in a path name does not exist.
        !            42: .{n 3 \s-1ESRCH\s+1 "No such process"
        !            43: No process can be found corresponding to that specified by
        !            44: .I pid\^
        !            45: in
        !            46: .I kill\^
        !            47: or
        !            48: .IR ptrace .
        !            49: .{n 4 \s-1EINTR\s+1 "Interrupted system call"
        !            50: An asynchronous signal (such as interrupt or quit),
        !            51: which the user has elected to catch,
        !            52: occurred during a system call.
        !            53: If execution is resumed
        !            54: after processing the signal,
        !            55: it will appear as if the interrupted system call
        !            56: returned this error condition.
        !            57: .{n 5 \s-1EIO\s+1 "I/O error"
        !            58: Some physical I/O error has occurred.
        !            59: This error may in some cases occur
        !            60: on a call following the one to which it actually applies.
        !            61: .{n 6 \s-1ENXIO\s+1 "No such device or address"
        !            62: I/O on a special file refers to a subdevice which does not
        !            63: exist,
        !            64: or beyond the limits of the device.
        !            65: It may also occur when, for example, a tape drive
        !            66: is not on-line or no disk pack is loaded on a drive.
        !            67: .{n 7 \s-1E2BIG\s+1 "Arg list too long"
        !            68: An argument list longer than 5,120 bytes
        !            69: is presented to a member of the
        !            70: .I exec\^
        !            71: family.
        !            72: .{n 8 \s-1ENOEXEC\s+1 "Exec format error"
        !            73: A request is made to execute a file
        !            74: which, although it has the appropriate permissions,
        !            75: does not start with a valid magic number (see
        !            76: .IR a.out (4)).
        !            77: .{n 9 \s-1EBADF\s+1 "Bad file number"
        !            78: Either a file descriptor refers to no
        !            79: open file,
        !            80: or a read (respectively, write) request is made to
        !            81: a file which is open only for writing (respectively, reading).
        !            82: .{n 10 \s-1ECHILD\s+1 "No child processes"
        !            83: A
        !            84: .I wait
        !            85: was executed by a process that had no existing or unwaited-for child processes.
        !            86: .{n 11 \s-1EAGAIN\s+1 "No more processes"
        !            87: A
        !            88: .I fork
        !            89: failed because the system's process table is full
        !            90: or the user is not allowed to create any more
        !            91: processes.
        !            92: .{n 12 \s-1ENOMEM\s+1 "Not enough space"
        !            93: During an
        !            94: .IR exec ,
        !            95: .IR brk ,
        !            96: or
        !            97: .IR sbrk ,
        !            98: a program asks for more space than the system is able to supply.
        !            99: This is not a temporary condition; the maximum space size
        !           100: is a system parameter.
        !           101: The error may also occur if the arrangement
        !           102: of text, data, and stack segments
        !           103: requires too many segmentation registers, or
        !           104: if there is not enough swap space during a
        !           105: .IR fork .
        !           106: .{n 13 \s-1EACCES\s+1 "Permission denied"
        !           107: An attempt was made to access a file in a way forbidden
        !           108: by the protection system.
        !           109: .{n 14 \s-1EFAULT\s+1 "Bad address"
        !           110: The system encountered a hardware fault in attempting to
        !           111: use an argument of a system call.
        !           112: .{n 15 \s-1ENOTBLK\s+1 "Block device required"
        !           113: A non-block file was mentioned where a block device was required,
        !           114: e.g., in
        !           115: .IR mount .
        !           116: .{n 16 \s-1EBUSY\s+1 "Device or resource busy"
        !           117: An attempt was made to mount a device that was already mounted or
        !           118: an attempt was made to dismount a device
        !           119: on which there is an active file
        !           120: (open file, current directory, mounted-on file, active text segment).
        !           121: It will also occur if an attempt is made to enable accounting when it is
        !           122: already enabled.
        !           123: The device or resource is currently unavailable.
        !           124: .{n 17 \s-1EEXIST\s+1 "File exists"
        !           125: An existing file was mentioned in an inappropriate context,
        !           126: e.g.,
        !           127: .IR link .
        !           128: .{n 18 \s-1EXDEV\s+1 "Cross-device link"
        !           129: A link to a file on another device
        !           130: was attempted.
        !           131: .{n 19 \s-1ENODEV\s+1 "No such device"
        !           132: An attempt was made to apply an inappropriate
        !           133: system call to a device;
        !           134: e.g., read a write-only device.
        !           135: .{n 20 \s-1ENOTDIR\s+1 "Not a directory"
        !           136: A non-directory was specified where a directory
        !           137: is required,
        !           138: for example in a path prefix or
        !           139: as an argument to
        !           140: .IR chdir (2).
        !           141: .{n 21 \s-1EISDIR\s+1 "Is a directory"
        !           142: An attempt was made to write on a directory.
        !           143: .{n 22 \s-1EINVAL\s+1 "Invalid argument"
        !           144: Some invalid argument (e.g., dismounting a non-mounted device;
        !           145: mentioning an undefined signal in
        !           146: .IR signal ,
        !           147: or
        !           148: .IR kill ;
        !           149: reading or writing a file for which
        !           150: .I lseek\^
        !           151: has generated a negative pointer).
        !           152: Also set by the math functions described in the (3M) entries
        !           153: of this manual.
        !           154: .{n 23 \s-1ENFILE\s+1 "File table overflow"
        !           155: The system file table is full,
        !           156: and temporarily no more
        !           157: .I opens\^
        !           158: can be accepted.
        !           159: .{n 24 \s-1EMFILE\s+1 "Too many open files"
        !           160: No process may have more than 20 file descriptors open at a time.
        !           161: .{n 25 \s-1ENOTTY\s+1 "Not a character device"
        !           162: An attempt was made to \f2ioctl\fR(2) a file that
        !           163: is not a special character device.
        !           164: .{n 26 \s-1ETXTBSY\s+1 "Text file busy"
        !           165: An attempt was made to execute a pure-procedure
        !           166: program that is currently open for writing.
        !           167: Also an attempt to open for writing a pure-procedure
        !           168: program that is being executed.
        !           169: .{n 27 \s-1EFBIG\s+1 "File too large"
        !           170: The size of a file exceeded the maximum
        !           171: file size (1,082,201,088 bytes) or
        !           172: .SM ULIMIT\*S;
        !           173: see
        !           174: .IR ulimit (2).
        !           175: .{n 28 \s-1ENOSPC\s+1 "No space left on device"
        !           176: During a
        !           177: .I write\^
        !           178: to an ordinary file,
        !           179: there is no free space left on the device.
        !           180: .{n 29 \s-1ESPIPE\s+1 "Illegal seek"
        !           181: An
        !           182: .I lseek\^
        !           183: was issued to a pipe.
        !           184: .{n 30 \s-1EROFS\s+1 "Read-only file system"
        !           185: An attempt to modify a file or directory
        !           186: was made
        !           187: on a device mounted read-only.
        !           188: .{n 31 \s-1EMLINK\s+1 "Too many links"
        !           189: An attempt to make more than the maximum number of links (1000) to a file.
        !           190: .{n 32 \s-1EPIPE\s+1 "Broken pipe"
        !           191: A write on a pipe for which there is no process
        !           192: to read the data.
        !           193: This condition normally generates a signal;
        !           194: the error is returned if the signal is ignored.
        !           195: .{n 33 \s-1EDOM\s+1 "Math argument"
        !           196: The argument of a function in the math package (3M)
        !           197: is out of the domain of the function.
        !           198: .{n 34 \s-1ERANGE\s+1 "Result too large"
        !           199: The value of a function in the math package (3M)
        !           200: is not representable within machine precision.
        !           201: .{n 35 \s-1EWOULDBLOCK\s+1 "Operation would block"
        !           202: An operation which would cause a process to block was attempted
        !           203: on a object in non-blocking mode (see \fIioctl\fP (2)).
        !           204: .{n 36 \s-1EINPROGRESS\s+1 "Operation now in progress"
        !           205: An operation which takes a long time to complete (such as
        !           206: a \fIconnect\fP (2)) was attempted on a non-blocking object (see
        !           207: \fIioctl\fP (2)).
        !           208: .{n 37 \s-1EALREADY\s+1 "Operation already in progress"
        !           209: An operation was attempted on a non-blocking object which already
        !           210: had an operation in progress.
        !           211: .{n 38 \s-1ENOTSOCK\s+1 "Socket operation on non-socket"
        !           212: Self-explanatory.
        !           213: .{n 39 \s-1EDESTADDRREQ\s+1 "Destination address required"
        !           214: A required address was omitted from an operation on a socket.
        !           215: .{n 40 \s-1EMSGSIZE\s+1 "Message too long"
        !           216: A message sent on a socket was larger than the internal message buffer.
        !           217: .{n 41 \s-1EPROTOTYPE\s+1 "Protocol wrong type for socket"
        !           218: A protocol was specified which does not support the semantics of the
        !           219: socket type requested. For example you cannot use the ARPA Internet
        !           220: UDP protocol with type SOCK_STREAM.
        !           221: .{n 42 \s-1ENOPROTOOPT\s+1 "Bad protocol option"
        !           222: A bad option was specified in a
        !           223: .IR getsockopt (2)
        !           224: or
        !           225: .IR setsockopt (2)
        !           226: call.
        !           227: .{n 43 \s-1EPROTONOSUPPORT\s+1 "Protocol not supported"
        !           228: The protocol has not been configured into the
        !           229: system or no implementation for it exists.
        !           230: .{n 44 \s-1ESOCKTNOSUPPORT\s+1 "Socket type not supported"
        !           231: The support for the socket type has not been configured into the
        !           232: system or no implementation for it exists.
        !           233: .{n 45 \s-1EOPNOTSUPP\s+1 "Operation not supported on socket"
        !           234: For example, trying to \fIaccept\fP a connection on a datagram socket.
        !           235: .{n 46 \s-1EPFNOSUPPORT\s+1 "Protocol family not supported"
        !           236: The protocol family has not been configured into the
        !           237: system or no implementation for it exists.
        !           238: .{n 47 \s-1EAFNOSUPPORT\s+1 "Address family not supported by protocol family"
        !           239: An address incompatible with the requested protocol was used.
        !           240: For example, you shouldn't necessarily expect to be able to use PUP
        !           241: Internet addresses with ARPA Internet protocols.
        !           242: .{n 48 \s-1EADDRINUSE\s+1 "Address already in use"
        !           243: Only one usage of each address is normally permitted.
        !           244: .{n 49 \s-1EADDRNOTAVAIL\s+1 "Can't assign requested address"
        !           245: Normally results from an attempt to create a socket with an
        !           246: address not on this machine.
        !           247: .{n 50 \s-1ENETDOWN\s+1 "Network is down"
        !           248: A socket operation encountered a dead network.
        !           249: .{n 51 \s-1ENETUNREACH\s+1 "Network is unreachable"
        !           250: A socket operation was attempted to an unreachable network.
        !           251: .{n 52 \s-1ENETRESET\s+1 "Network dropped connection on reset"
        !           252: The host you were connected to crashed and rebooted.
        !           253: .{n 53 \s-1ECONNABORTED\s+1 "Software caused connection abort"
        !           254: A connection abort was caused internal to your host machine.
        !           255: .{n 54 \s-1ECONNRESET\s+1 "Connection reset by peer"
        !           256: A connection was forcibly closed by a peer.  This normally
        !           257: results from the peer executing a \fIshutdown\fP (2) call.
        !           258: .{n 55 \s-1ENOBUFS\s+1 "No buffer space available"
        !           259: An operation on a socket or pipe was not performed because
        !           260: the system lacked sufficient buffer space.
        !           261: .{n 56 \s-1EISCONN\s+1 "Socket is already connected"
        !           262: A
        !           263: .I connect
        !           264: request was made on an already connected socket; or,
        !           265: a
        !           266: .I sendto
        !           267: or
        !           268: .I sendmsg
        !           269: request on a connected socket specified a destination
        !           270: other than the connected party.
        !           271: .{n 57 \s-1ENOTCONN\s+1 "Socket is not connected"
        !           272: An request to send or receive data was disallowed because
        !           273: the socket is not connected.
        !           274: .{n 58 \s-1ESHUTDOWN\s+1 "Can't send after socket shutdown"
        !           275: A request to send data was disallowed because the socket
        !           276: had already been shut down with a previous
        !           277: .IR shutdown (2)
        !           278: call.
        !           279: .{n 59 \fIunused\fP
        !           280: .{n 60 \s-1ETIMEDOUT\s+1 "Connection timed out"
        !           281: A
        !           282: .I connect
        !           283: request failed because the connected party did not
        !           284: properly respond after a period of time.  (The timeout
        !           285: period is dependent on the communication protocol.)
        !           286: .{n 61 \s-1ECONNREFUSED\s+1 "Connection refused"
        !           287: No connection could be made because the target machine actively
        !           288: refused it.  This usually results from trying to connect
        !           289: to a service which is inactive on the foreign host.
        !           290: .{n 62 \s-1ELOOP\s+1 "Too many levels of symbolic links"
        !           291: A path name lookup involved more than 8 symbolic links.
        !           292: .{n 63 \s-1ENAMETOOLONG\s+1 "File name too long"
        !           293: A component of a path name exceeded 255 characters, or an entire
        !           294: path name exceeded 1023 characters.
        !           295: .{n 64 \s-1EHOSTDOWN\s+1 "Host is down"
        !           296: The host machine is not up.
        !           297: .{n 65 \s-1EHOSTUNREACH\s+1 "No route to host"
        !           298: The host machine cannot be reached.
        !           299: .{n 66 \s-1ENOTEMPTY\s+1 "Directory not empty"
        !           300: A directory with entries other than \*(lq.\*(rq and \*(lq..\*(rq
        !           301: was supplied to a remove directory or rename call.
        !           302: .{n 67 \fIunused\fP
        !           303: .{n 68 \s-1EUSERS\s+1 "Too many users"
        !           304: The quota table is full.
        !           305: .{n 69 \s-1EDQUOT\s+1 "Disc quota exceeded"
        !           306: A process has exceeded its disk quota.
        !           307: .{n 70 \s-1ENOMSG\s+1 "No message of desired type"
        !           308: An attempt was made to receive a message of a type
        !           309: that does not exist on the specified message queue; see
        !           310: .IR msgop (2).
        !           311: .{n 71 \s-1EIDRM\s+1 "Identifier Removed"
        !           312: This error is returned to processes that resume execution due to the removal
        !           313: of an identifier from the file system's name space (see
        !           314: .IR msgctl "(2), " semctl "(2), and " shmctl (2)).
        !           315: .SH "DEFINITIONS"
        !           316: .SS "Process \s-1ID\s+1"
        !           317: Each active process in the system is uniquely identified by a
        !           318: positive integer called a process
        !           319: .SM ID\*S.
        !           320: The range of this
        !           321: .SM ID
        !           322: is from 1 to 30,000.
        !           323: .SS "Parent Process \s-1ID\s+1"
        !           324: A new process is created by a currently active
        !           325: process; see
        !           326: .IR fork (2).
        !           327: The parent process
        !           328: .SM ID
        !           329: of a process is the process
        !           330: .SM ID
        !           331: of its creator.
        !           332: .SS "Process Group \s-1ID\s+1"
        !           333: Each active process is a member of a process group that is
        !           334: identified by a positive integer called the process group
        !           335: .SM ID\*S.
        !           336: This
        !           337: .SM ID
        !           338: is the process
        !           339: .SM ID
        !           340: of the group leader.
        !           341: This grouping permits the signaling of related processes; see
        !           342: .IR kill (2).
        !           343: .SS "Tty Group \s-1ID\s+1"
        !           344: Each active process can be a member of a terminal group that
        !           345: is identified by a positive integer called the tty group
        !           346: .SM ID\*S.
        !           347: This grouping is used to terminate a group of related processes upon termination
        !           348: of one of the processes in the group; see
        !           349: .IR exit (2)
        !           350: and
        !           351: .IR signal (2).
        !           352: .SS "Real User \s-1ID\s+1 and Real Group \s-1ID\s+1"
        !           353: Each user allowed on the system is 
        !           354: identified by a positive integer called a real user
        !           355: .SM ID\*S.
        !           356: .PP
        !           357: Each user is also a member of a group.
        !           358: The group is identified by a positive integer called the real group
        !           359: .SM ID\*S.
        !           360: .PP
        !           361: An active process has a real user
        !           362: .SM ID
        !           363: and real group
        !           364: .SM ID
        !           365: that are set to the real user
        !           366: .SM ID
        !           367: and real group
        !           368: .SM ID\*S,
        !           369: respectively, of the user responsible for the creation of the process.
        !           370: .SS "Effective User \s-1ID\s+1 and Effective Group \s-1ID\s+1"
        !           371: An active process has an effective user
        !           372: .SM ID
        !           373: and an effective group
        !           374: .SM ID
        !           375: that are used to determine file access permissions (see below).
        !           376: The effective
        !           377: user
        !           378: .SM ID
        !           379: and effective group
        !           380: .SM ID
        !           381: are equal to the process's real user
        !           382: .SM ID
        !           383: and real group
        !           384: .SM ID
        !           385: respectively, unless the process
        !           386: or one of its ancestors evolved from a file that had the set-user-\s-1ID\s+1
        !           387: bit or set-group
        !           388: .SM ID
        !           389: bit set; see
        !           390: .IR exec (2).
        !           391: .SS Super-user
        !           392: A process is recognized as a
        !           393: .I super-user\^
        !           394: process and is granted special privileges if its effective user
        !           395: .SM ID
        !           396: is 0.
        !           397: .SS "Special Processes"
        !           398: The processes with a process
        !           399: .SM ID
        !           400: of 0 and a process
        !           401: .SM ID
        !           402: of 1 are special processes and are referred to as
        !           403: .IR proc0 " and " proc1.
        !           404: .PP
        !           405: .I Proc0\^
        !           406: is the scheduler.
        !           407: .I Proc1\^
        !           408: is the initialization process 
        !           409: .RI ( init ).
        !           410: Proc1 is the ancestor of every other
        !           411: process in the system and is used to control the process structure.
        !           412: .SS File Descriptor
        !           413: A file descriptor is a small integer used
        !           414: to do \s-1I/O\s+1 on a file.
        !           415: The value of a file descriptor is from
        !           416: 0 to 19.
        !           417: A process may have no more than 20 file descriptors (0-19)
        !           418: open simultaneously.
        !           419: A file descriptor is returned by system calls such as
        !           420: \f2open\fR(2),
        !           421: or \f2pipe\fR(2).
        !           422: The file descriptor is used as an
        !           423: argument by calls such as
        !           424: \f2read\fR(2),
        !           425: \f2write\fR(2),
        !           426: \f2ioctl\fR(2),
        !           427: and
        !           428: \f2close\fR(2).
        !           429: .SS "File Name"
        !           430: Names consisting of 1 to 14 characters may be used to name an ordinary file,
        !           431: special file or directory.
        !           432: .PP
        !           433: These characters may be selected from the set of all character values
        !           434: excluding \e0 (null) and the
        !           435: .SM ASCII
        !           436: code for
        !           437: .B /
        !           438: (slash).
        !           439: .PP
        !           440: Note that it is generally unwise to use
        !           441: .BR "*" ,
        !           442: .BR "?" ,
        !           443: .BR "[" ,
        !           444: or
        !           445: .B "]"
        !           446: as part of file names because of the special meaning attached to these
        !           447: characters by the shell.
        !           448: See
        !           449: .IR sh (1).
        !           450: Although permitted, it is advisable to avoid the use of unprintable
        !           451: characters in file names.
        !           452: .SS "Path Name and Path Prefix"
        !           453: A path name is a null-terminated character string
        !           454: starting with an optional slash
        !           455: .RB ( / ),
        !           456: followed by
        !           457: zero or more directory names separated by slashes, optionally followed
        !           458: by a file name.
        !           459: .PP
        !           460: More precisely, a path name is a null-terminated character string
        !           461: constructed as follows:
        !           462: .PP
        !           463: .RS
        !           464: <path-name>::=<file-name>\(bv<path-prefix><file-name>|/
        !           465: .br
        !           466: <path-prefix>::=<rtprefix>\(bv/<rtprefix>
        !           467: .br
        !           468: <rtprefix>::=<dirname>/\(bv<rtprefix><dirname>/
        !           469: .RE
        !           470: .PP
        !           471: where <file-name> is a string of 1 to 14
        !           472: characters other than the
        !           473: .SM ASCII
        !           474: slash and null, and
        !           475: <dirname> is a string of 1 to 14 characters
        !           476: (other than the
        !           477: .SM ASCII
        !           478: slash and null)
        !           479: that names a directory.
        !           480: .PP
        !           481: If a path name begins with a slash, the path search begins at the
        !           482: .I root\^
        !           483: directory.
        !           484: Otherwise, the search begins from the current working directory.
        !           485: .PP
        !           486: A slash by itself names the root directory.
        !           487: .PP
        !           488: Unless specifically stated otherwise,
        !           489: the null path name is treated as if it named
        !           490: a non-existent file.
        !           491: .SS Directory
        !           492: .PP
        !           493: Directory entries are called links.
        !           494: By convention, a directory contains at least two links,
        !           495: .B  .
        !           496: and
        !           497: .BR .. ,
        !           498: referred to as
        !           499: .I dot\^
        !           500: and
        !           501: .I dot-dot\^
        !           502: respectively.
        !           503: Dot refers to the directory itself and dot-dot refers to its parent
        !           504: directory.
        !           505: .SS "Root Directory and Current Working Directory"
        !           506: Each process has associated with it a concept of a root directory and
        !           507: a current working directory for the purpose of resolving path name searches.
        !           508: The root directory of a process need not be the root directory of the root
        !           509: file system.
        !           510: .SS "File Access Permissions"
        !           511: .PP
        !           512: Read, write, and execute/search permissions on a file are
        !           513: granted to a process if one or more of the following are true:
        !           514: .IP
        !           515: The effective user
        !           516: .SM ID
        !           517: of the process
        !           518: is super-user.
        !           519: .IP
        !           520: The effective user
        !           521: .SM ID
        !           522: of the process
        !           523: matches the user
        !           524: .SM ID
        !           525: of the owner of the file
        !           526: and the appropriate access bit of the
        !           527: ``owner'' portion (0700) of the file mode is set.
        !           528: .IP
        !           529: The effective user
        !           530: .SM ID
        !           531: of the process
        !           532: does not match the user
        !           533: .SM ID
        !           534: of the owner of the file,
        !           535: and the effective group
        !           536: .SM ID
        !           537: of the process
        !           538: matches the group of the file and
        !           539: the appropriate access bit of the ``group'' portion
        !           540: (070) of the file mode is set.
        !           541: .IP
        !           542: The effective user
        !           543: .SM ID
        !           544: of the process
        !           545: does not match the user
        !           546: .SM ID
        !           547: of the owner of the file,
        !           548: and the effective group
        !           549: .SM ID
        !           550: of the process
        !           551: does not match the group
        !           552: .SM ID
        !           553: of the file,
        !           554: and the appropriate access bit of the ``other'' portion (07) of the
        !           555: file mode is set.
        !           556: .PP
        !           557: Otherwise, the corresponding permissions are denied.
        !           558: .SS "Message Queue Identifier"
        !           559: A message queue identifier (msqid) is a unique positive integer created by a
        !           560: .IR msgget (2)
        !           561: system call.
        !           562: Each msqid has a message queue and a data structure associated with it.
        !           563: The data structure is referred to as
        !           564: .I msqid_ds
        !           565: and contains the following members:
        !           566: .PP
        !           567: .RS
        !           568: .ta 8n 28n
        !           569: .nf
        !           570: struct ipc_perm msg_perm;      /\(** operation permission struct \(**/
        !           571: ushort msg_cbytes;     /\(** current number of bytes on q \(**/
        !           572: ushort msg_qnum;       /\(** number of msgs on q \(**/
        !           573: ushort msg_qbytes;     /\(** max number of bytes on q \(**/
        !           574: ushort msg_lspid;      /\(** pid of last msgsnd operation \(**/
        !           575: ushort msg_lrpid;      /\(** pid of last msgrcv operation \(**/
        !           576: time_t msg_stime;      /\(** last msgsnd time \(**/
        !           577: time_t msg_rtime;      /\(** last msgrcv time \(**/
        !           578: time_t msg_ctime;      /\(** last change time \(**/
        !           579:                /\(** Times measured in secs since \(**/
        !           580:                /\(** 00:00:00 \s-1GMT\s+1, Jan. 1, 1970 \(**/
        !           581: .fi
        !           582: .RE
        !           583: .PP
        !           584: .B Msg_perm
        !           585: is an ipc_perm structure that
        !           586: specifies the message operation permission (see below).
        !           587: This structure includes the following members:
        !           588: .PP
        !           589: .RS
        !           590: .ta 8n 20n
        !           591: .nf
        !           592: ushort cuid;   /\(** creator user id \(**/
        !           593: ushort cgid;   /\(** creator group id \(**/
        !           594: ushort uid;    /\(** user id \(**/
        !           595: ushort gid;    /\(** group id \(**/
        !           596: ushort mode;   /\(** r/w permission \(**/
        !           597: .PP
        !           598: .fi
        !           599: .RE
        !           600: .B Msg_cbytes
        !           601: is the current number of bytes on the queue.
        !           602: .B Msg_qnum
        !           603: is the number of messages currently on the queue.
        !           604: .B Msg_qbytes
        !           605: is the maximum number of bytes allowed on the queue.
        !           606: .B Msg_lspid
        !           607: is the process id of the last process that performed a
        !           608: .IR msgsnd " operation."
        !           609: .B Msg_lrpid
        !           610: is the process id of the last process that performed a
        !           611: .IR msgrcv " operation."
        !           612: .B Msg_stime
        !           613: is the time of the last
        !           614: .I msgsnd
        !           615: operation,
        !           616: .B msg_rtime
        !           617: is the time of the last
        !           618: .I msgrcv
        !           619: operation, and
        !           620: .B msg_ctime
        !           621: is the time of the last
        !           622: .IR msgctl (2)
        !           623: operation that changed a member of the above structure.
        !           624: .SS "Message Operation Permissions"
        !           625: In the
        !           626: .IR msgop "(2) and " msgctl (2)
        !           627: system call descriptions, the permission required
        !           628: for an operation is given as "{token}", where "token" is the type
        !           629: of permission needed interpreted as follows:
        !           630: .PP
        !           631: .RS 0.75i
        !           632: .PD 0
        !           633: .TP 1.50i
        !           634: 00400
        !           635: Read by user
        !           636: .TP
        !           637: 00200
        !           638: Write by user
        !           639: .TP
        !           640: 00060
        !           641: Read, Write by group
        !           642: .TP
        !           643: 00006
        !           644: Read, Write by others
        !           645: .RE
        !           646: .PD
        !           647: .PP
        !           648: Read and Write permissions on a msqid are
        !           649: granted to a process if one or more of the following are true:
        !           650: .IP
        !           651: The effective user
        !           652: .SM ID
        !           653: of the process
        !           654: is super-user.
        !           655: .IP
        !           656: The effective user
        !           657: .SM ID
        !           658: of the process
        !           659: matches
        !           660: .B msg_perm.[c]uid
        !           661: in the data structure associated with
        !           662: .I msqid
        !           663: and the appropriate bit of the
        !           664: ``user'' portion (0600) of
        !           665: .B msg_perm.mode
        !           666: is set.
        !           667: .IP
        !           668: The effective user
        !           669: .SM ID
        !           670: of the process
        !           671: does not match
        !           672: .B msg_perm.[c]uid
        !           673: and the effective group
        !           674: .SM ID
        !           675: of the process
        !           676: matches
        !           677: .B msg_perm.[c]gid
        !           678: and the appropriate bit of the ``group'' portion
        !           679: (060) of
        !           680: .B msg_perm.mode
        !           681: is set.
        !           682: .IP
        !           683: The effective user
        !           684: .SM ID
        !           685: of the process
        !           686: does not match
        !           687: .B msg_perm.[c]uid
        !           688: and the effective group
        !           689: .SM ID
        !           690: of the process
        !           691: does not match
        !           692: .B msg_perm.[c]gid
        !           693: and the appropriate bit of the ``other'' portion (06) of
        !           694: .B msg_perm.mode
        !           695: is set.
        !           696: .PP
        !           697: Otherwise, the corresponding permissions are denied.
        !           698: .SS "Semaphore Identifier"
        !           699: A semaphore identifier (semid) is a unique positive integer created by a
        !           700: .IR semget (2)
        !           701: system call.
        !           702: Each semid has a set of semaphores and a data structure associated with it.
        !           703: The data structure is referred to as
        !           704: .I semid_ds
        !           705: and contains the following members:
        !           706: .PP
        !           707: .RS
        !           708: .ta 8n 28n
        !           709: .nf
        !           710: struct ipc_perm sem_perm;      /\(** operation permission struct \(**/
        !           711: ushort sem_nsems;      /\(** number of sems in set \(**/
        !           712: time_t sem_otime;      /\(** last operation time \(**/
        !           713: time_t sem_ctime;      /\(** last change time \(**/
        !           714:                /\(** Times measured in secs since \(**/
        !           715:                /\(** 00:00:00 \s-1GMT\s+1, Jan. 1, 1970 \(**/
        !           716: .fi
        !           717: .RE
        !           718: .PP
        !           719: .B Sem_perm
        !           720: is an ipc_perm structure that
        !           721: specifies the semaphore operation permission (see below).
        !           722: This structure includes the following members:
        !           723: .PP
        !           724: .RS
        !           725: .ta 8n 20n
        !           726: .nf
        !           727: ushort cuid;   /\(** creator user id \(**/
        !           728: ushort cgid;   /\(** creator group id \(**/
        !           729: ushort uid;    /\(** user id \(**/
        !           730: ushort gid;    /\(** group id \(**/
        !           731: ushort mode;   /\(** r/a permission \(**/
        !           732: .PP
        !           733: .fi
        !           734: .RE
        !           735: The value of
        !           736: .B sem_nsems
        !           737: is equal to the number of semaphores in the set.
        !           738: Each semaphore in the set is referenced by a positive integer
        !           739: referred to as a
        !           740: .IR sem_num .
        !           741: Sem_num values run sequentially from 0 to the value of sem_nsems minus 1.
        !           742: .B Sem_otime
        !           743: is the time of the last
        !           744: .IR semop (2)
        !           745: operation, and
        !           746: .B sem_ctime
        !           747: is the time of the last
        !           748: .IR semctl (2)
        !           749: operation that changed a member of the above structure.
        !           750: .PP
        !           751: A semaphore is a data structure that contains the following members:
        !           752: .PP
        !           753: .RS
        !           754: .ta 8n 20n
        !           755: .nf
        !           756: ushort semval; /\(** semaphore value \(**/
        !           757: short  sempid; /\(** pid of last operation  \(**/
        !           758: ushort semncnt;        /\(** # awaiting semval > cval \(**/
        !           759: ushort semzcnt;        /\(** # awaiting semval = 0 \(**/
        !           760: .fi
        !           761: .RE
        !           762: .PP
        !           763: .B Semval
        !           764: is a non-negative integer.
        !           765: .B Sempid
        !           766: is equal to the process
        !           767: .SM ID
        !           768: of the last process that performed a semaphore operation on this semaphore.
        !           769: .B Semncnt
        !           770: is a count of the number of processes that are currently suspended
        !           771: awaiting this semaphore's semval to become greater than its current value.
        !           772: .B Semzcnt
        !           773: is a count of the number of processes that are currently suspended
        !           774: awaiting this semaphore's semval to become zero.
        !           775: .SS "Semaphore Operation Permissions"
        !           776: In the
        !           777: .IR semop "(2) and " semctl (2)
        !           778: system call descriptions, the permission required
        !           779: for an operation is given as "{token}", where "token" is the type
        !           780: of permission needed interpreted as follows:
        !           781: .PP
        !           782: .RS 0.75i
        !           783: .PD 0
        !           784: .TP 1.50i
        !           785: 00400
        !           786: Read by user
        !           787: .TP
        !           788: 00200
        !           789: Alter by user
        !           790: .TP
        !           791: 00060
        !           792: Read, Alter by group
        !           793: .TP
        !           794: 00006
        !           795: Read, Alter by others
        !           796: .RE
        !           797: .PD
        !           798: .PP
        !           799: Read and Alter permissions on a semid are
        !           800: granted to a process if one or more of the following are true:
        !           801: .IP
        !           802: The effective user
        !           803: .SM ID
        !           804: of the process
        !           805: is super-user.
        !           806: .IP
        !           807: The effective user
        !           808: .SM ID
        !           809: of the process
        !           810: matches
        !           811: .B sem_perm.[c]uid
        !           812: in the data structure associated with
        !           813: .I semid
        !           814: and the appropriate bit of the
        !           815: ``user'' portion (0600) of
        !           816: .B sem_perm.mode
        !           817: is set.
        !           818: .IP
        !           819: The effective user
        !           820: .SM ID
        !           821: of the process
        !           822: does not match
        !           823: .B sem_perm.[c]uid
        !           824: and the effective group
        !           825: .SM ID
        !           826: of the process
        !           827: matches
        !           828: .B sem_perm.[c]gid
        !           829: and the appropriate bit of the ``group'' portion
        !           830: (060) of
        !           831: .B sem_perm.mode
        !           832: is set.
        !           833: .IP
        !           834: The effective user
        !           835: .SM ID
        !           836: of the process
        !           837: does not match
        !           838: .B sem_perm.[c]uid
        !           839: and the effective group
        !           840: .SM ID
        !           841: of the process
        !           842: does not match
        !           843: .B sem_perm.[c]gid
        !           844: and the appropriate bit of the ``other'' portion (06) of
        !           845: .B sem_perm.mode
        !           846: is set.
        !           847: .PP
        !           848: Otherwise, the corresponding permissions are denied.
        !           849: .SS "Shared Memory Identifier"
        !           850: A shared memory identifier (shmid) is a unique positive integer created by a
        !           851: .IR shmget (2)
        !           852: system call.
        !           853: Each shmid has a segment of memory (referred to as a shared memory segment)
        !           854: and a data structure associated with it.
        !           855: The data structure is referred to as
        !           856: .I shmid_ds
        !           857: and contains the following members:
        !           858: .PP
        !           859: .RS
        !           860: .ta 8n 28n
        !           861: .nf
        !           862: struct ipc_perm shm_perm;      /\(** operation permission struct \(**/
        !           863: int    shm_segsz;      /\(** size of segment \(**/
        !           864: struct proc *shm_perm; /\(** address of linked proc \(**/
        !           865: short  shm_pidx;       /\(** index of this segment \(**/
        !           866: ushort shm_cpid;       /\(** creator pid \(**/
        !           867: ushort shm_lpid;       /\(** pid of last operation \(**/
        !           868: short  shm_cnattch;    /\(** number of loaded attaches \(**/
        !           869: short  shm_nattch;     /\(** number of current attaches \(**/
        !           870: time_t shm_atime;      /\(** last attach time \(**/
        !           871: time_t shm_dtime;      /\(** last detach time \(**/
        !           872: time_t shm_ctime;      /\(** last change time \(**/
        !           873:                /\(** Times measured in secs since \(**/
        !           874:                /\(** 00:00:00 \s-1GMT\s+1, Jan. 1, 1970 \(**/
        !           875: .fi
        !           876: .RE
        !           877: .PP
        !           878: .B Shm_perm
        !           879: is an ipc_perm structure that
        !           880: specifies the shared memory operation permission (see below).
        !           881: This structure includes the following members:
        !           882: .PP
        !           883: .RS
        !           884: .ta 8n 20n
        !           885: .nf
        !           886: ushort cuid;   /\(** creator user id \(**/
        !           887: ushort cgid;   /\(** creator group id \(**/
        !           888: ushort uid;    /\(** user id \(**/
        !           889: ushort gid;    /\(** group id \(**/
        !           890: ushort mode;   /\(** r/w permission \(**/
        !           891: .PP
        !           892: .fi
        !           893: .RE
        !           894: .B Shm_segsz
        !           895: specifies the size of the shared memory segment.
        !           896: .B Shm_proc
        !           897: is the address of the first process linked to this segment.
        !           898: .B Shm_pidx
        !           899: is the index of this shared memory segment in the shared memory table belonging
        !           900: to that process.
        !           901: .B Shm_cpid
        !           902: is the process id of the process that created the shared memory identifier.
        !           903: .B Shm_lpid
        !           904: is the process id of the last process that performed a
        !           905: .IR shmop "(2) operation."
        !           906: .B Shm_cnattch
        !           907: is the number of in-core processes attached to this segment.
        !           908: .B Shm_nattch
        !           909: is the number of processes that currently have this segment attached.
        !           910: .B Shm_atime
        !           911: is the time of the last
        !           912: .I shmat
        !           913: operation,
        !           914: .B shm_dtime
        !           915: is the time of the last
        !           916: .I shmdt
        !           917: operation,
        !           918: and
        !           919: .B shm_ctime
        !           920: is the time of the last
        !           921: .IR shmctl (2)
        !           922: operation that changed one of the members of the above structure.
        !           923: .SS "Shared Memory Operation Permissions"
        !           924: In the
        !           925: .IR shmop "(2) and " shmctl (2)
        !           926: system call descriptions, the permission required
        !           927: for an operation is given as "{token}", where "token" is the type
        !           928: of permission needed interpreted as follows:
        !           929: .PP
        !           930: .RS 0.75i
        !           931: .PD 0
        !           932: .TP 1.50i
        !           933: 00400
        !           934: Read by user
        !           935: .TP
        !           936: 00200
        !           937: Write by user
        !           938: .TP
        !           939: 00060
        !           940: Read, Write by group
        !           941: .TP
        !           942: 00006
        !           943: Read, Write by others
        !           944: .RE
        !           945: .PD
        !           946: .PP
        !           947: Read and Write permissions on a shmid are
        !           948: granted to a process if one or more of the following are true:
        !           949: .IP
        !           950: The effective user
        !           951: .SM ID
        !           952: of the process
        !           953: is super-user.
        !           954: .IP
        !           955: The effective user
        !           956: .SM ID
        !           957: of the process
        !           958: matches
        !           959: .B shm_perm.[c]uid
        !           960: in the data structure associated with
        !           961: .I shmid
        !           962: and the appropriate bit of the
        !           963: ``user'' portion (0600) of
        !           964: .B shm_perm.mode
        !           965: is set.
        !           966: .IP
        !           967: The effective user
        !           968: .SM ID
        !           969: of the process
        !           970: does not match
        !           971: .B shm_perm.[c]uid
        !           972: and the effective group
        !           973: .SM ID
        !           974: of the process
        !           975: matches
        !           976: .B shm_perm.[c]gid
        !           977: and the appropriate bit of the ``group'' portion
        !           978: (060) of
        !           979: .B shm_perm.mode
        !           980: is set.
        !           981: .IP
        !           982: The effective user
        !           983: .SM ID
        !           984: of the process
        !           985: does not match
        !           986: .B shm_perm.[c]uid
        !           987: and the effective group
        !           988: .SM ID
        !           989: of the process
        !           990: does not match
        !           991: .B shm_perm.[c]gid
        !           992: and the appropriate bit of the ``other'' portion (06) of
        !           993: .B shm_perm.mode
        !           994: is set.
        !           995: .PP
        !           996: Otherwise, the corresponding permissions are denied.
        !           997: .SS "System Five Interfaces Library"
        !           998: The following system calls constitute the system 5 interfaces library:
        !           999: .PP
        !          1000: .RS
        !          1001: .IR msgctl ,
        !          1002: .br
        !          1003: .IR msgget ,
        !          1004: .br
        !          1005: .IR msgrcv ,
        !          1006: .br
        !          1007: .IR msgsnd ,
        !          1008: .br
        !          1009: .IR plock ,
        !          1010: .br
        !          1011: .IR semctl ,
        !          1012: .br
        !          1013: .IR semget ,
        !          1014: .br
        !          1015: .IR semop ,
        !          1016: .br
        !          1017: .IR shmat ,
        !          1018: .br
        !          1019: .IR shmctl ,
        !          1020: .br
        !          1021: .IR shmdt ,
        !          1022: .br
        !          1023: .IR shmget ,
        !          1024: .br
        !          1025: .IR ulimit ,
        !          1026: .br
        !          1027: .IR uname ,
        !          1028: .br
        !          1029: .IR ustat ,
        !          1030: .RE
        !          1031: .SH NOTES
        !          1032: This manual page replaces the 4.2BSD manual page.
        !          1033: .SH FILES
        !          1034: .nf
        !          1035: /usr/lib/libsys5.a     System Five Interfaces Library
        !          1036: .fi
        !          1037: .SH SEE ALSO
        !          1038: close(2),
        !          1039: ioctl(2),
        !          1040: open(2),
        !          1041: pipe(2),
        !          1042: read(2),
        !          1043: write(2),
        !          1044: intro(3).
        !          1045: .\"    @(#)intro.2     6.2 of 9/6/83

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