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intro(2)

Intro(2)                         System Calls                         Intro(2)



NAME
       Intro, intro - introduction to system calls and error numbers

SYNOPSIS
       #include <errno.h>

DESCRIPTION
       A  system call is a C library function that requests a service from the
       system, such as getting the time of day. This request is  performed  in
       the  kernel.  The  library  interface  executes a trap into the kernel,
       which actually executes the system call code.


       Most system calls return one or more error conditions. An error  condi‐
       tion  is  indicated  by  an  otherwise impossible return value. This is
       almost always −1 or the null pointer; the individual descriptions spec‐
       ify  the  details.  An  error  number is made available in the external
       variable errno, which is not cleared on  successful  calls.  So  it  is
       tested only after an error has been indicated.


       Every  thread  has  a  unique  errno value specific to that thread. The
       errno variable is implemented as a  macro  that  references  this  per-
       thread  value.  This  errno  macro  can  be  used on either side of the
       assignment as though it were a variable. Prior to  the  Oracle  Solaris
       11.4 release, it was necessary to specify the -mt option on the command
       line at compilation time to enable  the  per-thread  implementation  of
       errno. The -mt option is no longer required.


       An error value listed as "will fail" describes a condition whose detec‐
       tion and reporting is mandatory for an implementation that conforms  to
       the  Single  UNIX  Specification (SUS). An application can rely on this
       condition being detected and reported. An error value  listed  as  "may
       fail"  describes  a condition whose detection and reporting is optional
       for an implementation that conforms to the SUS. An  application  should
       not  rely on this condition being detected and reported. An application
       that relies on such behavior cannot be assured to  be  portable  across
       conforming implementations. If more than one error occurs in processing
       a function call, any one of the possible errors may be returned, as the
       order  of  detection  is  undefined. For more information on additional
       information regarding the Single UNIX Specification,  see  standards(7)
       man page.


       Each  system  call description attempts to list all possible error num‐
       bers. The following list gives the description of the error numbers and
       their names as defined in <errno.h>.

       1 EPERM                Lacking appropriate privileges

                              This error indicates an attempt to modify a file
                              in a way forbidden except to  its  owner  or  an
                              appropriately  privileged  process.  It  is also
                              returned when ordinary users attempt to  perform
                              operations  allowed  only to processes with cer‐
                              tain privileges.

                              The manual pages for individual functions  docu‐
                              ment which privileges are needed to override the
                              restriction.


       2 ENOENT               No such file or directory

                              This error occurs when a file name is  specified
                              but the file doesn't exist, or one of the direc‐
                              tories in the path name does not exist.


       3 ESRCH                No such process, LWP, or thread

                              This error occurs when no process can  be  found
                              in  the system that corresponds to the specified
                              PID,  LWPID_t, or thread_t.


       4 EINTR                Interrupted system call

                              This error occurs when  an  asynchronous  signal
                              (such  as interrupt or quit), which the user has
                              elected to catch, occurred during a system  ser‐
                              vice  function.  If  execution  is resumed after
                              processing the signal, it will appear as if  the
                              interrupted  function  call  returned this error
                              condition.

                              In a multithreaded  application,  EINTR  may  be
                              returned  whenever  another  thread or LWP calls
                              fork(2).


       5 EIO                  I/O error

                              Some physical I/O error has  occurred.  In  some
                              cases,  this error may occur on a call following
                              the one to which it actually applies.


       6 ENXIO                No such device or address

                              This error occurs when I/O  on  a  special  file
                              refers  to  a subdevice which does not exist, or
                              exists beyond the limit of the  device.  It  may
                              also  occur  when,  for example, a tape drive is
                              not on-line or no  disk  pack  is  loaded  on  a
                              drive.


       7 E2BIG                Arg list too long

                              This  error  occurs when an argument list longer
                              than ARG_MAX bytes is presented to a  member  of
                              the  exec family of functions (see exec(2)). The
                              argument list limit is the sum of  the  size  of
                              the  argument list plus the size of the environ‐
                              ment's exported shell variables.


       8 ENOEXEC              Exec format error

                              This error occurs when a request is made to exe‐
                              cute a file which, although it has the appropri‐
                              ate permissions, does not  start  with  a  valid
                              format (see a.out(5)).


       9 EBADF                Bad file number

                              This  error occurs when either a file descriptor
                              refers to no open file, or  a  read(2)  (respec‐
                              tively, write(2)) request is made to a file that
                              is open only for  writing  (respectively,  read‐
                              ing).


       10 ECHILD              No child processes

                              This  error occurs when a wait(3C) function call
                              is executed by a process that has no existing or
                              unwaited-for child processes.


       11 EAGAIN              No more processes, or no more LWPs

                              For example, the fork(2) function failed because
                              the system's process table is full or  the  user
                              is  not allowed to create any more processes, or
                              a call failed because of insufficient memory  or
                              swap space.


       12 ENOMEM              Not enough space

                              This  error  occurs during execution of brk() or
                              sbrk() (see brk(2)), or one of the  exec  family
                              of functions. A program asks for more space than
                              the system is able to supply. This is not a tem‐
                              porary  condition;  the maximum size is a system
                              parameter. On some architectures, the error  may
                              also occur if the arrangement of text, data, and
                              stack segments requires  too  many  segmentation
                              registers,  or if there is not enough swap space
                              during the fork(2) function.


       13 EACCES              Permission denied

                              This error occurs when an  attempt  is  made  to
                              access  a file in a way forbidden by the protec‐
                              tion system.

                              The manual pages for individual functions  docu‐
                              ment  the privileges that are needed to override
                              the protection system.


       14 EFAULT              Bad address

                              This error occurs when the system  encounters  a
                              hardware  fault in attempting to use an argument
                              of a routine. For example, errno potentially may
                              be set to EFAULT any time a routine that takes a
                              pointer argument is passed an  invalid  address,
                              if  the  system  can detect the condition. Since
                              systems differ  in  their  ability  to  reliably
                              detect  a  bad  address, on some implementations
                              passing a bad address to a routine  will  result
                              in undefined behavior. Examples of a bad address
                              include but are not limited to  an  address  not
                              mapped  into  the  user's  address  space  or an
                              address with an incorrect ADI version. For  more
                              information, see the adi(3C) man page.


       15 ENOTBLK             Block device required

                              This  error  occurs  when  a non-block device or
                              file  is  mentioned  where  a  block  device  is
                              required (for example, in a call to the mount(2)
                              function).


       16 EBUSY               Device busy

                              This error occurs when an  attempt  is  made  to
                              mount  a  device  that  is already mounted or an
                              attempt is made to unmount  a  device  on  which
                              there  is  an  active  file  (open file, current
                              directory, mounted-on  file,  active  text  seg‐
                              ment).  It will also occur if an attempt is made
                              to enable accounting when it is already enabled.
                              The device or resource is currently unavailable.
                              EBUSY is also used by mutexes, semaphores,  con‐
                              dition  variables,  and  r/w  locks, to indicate
                              that a lock is held, and by the  processor  con‐
                              trol function P_ONLINE.


       17 EEXIST              File exists

                              This  error occurs when an existing file is men‐
                              tioned in an inappropriate context (for example,
                              call to the link(2) function).


       18 EXDEV               Cross-device link

                              This  error occurs when a hard link to a file on
                              another device is attempted.


       19 ENODEV              No such device

                              This error occurs when an  attempt  is  made  to
                              apply  an  inappropriate  operation  to a device
                              (for example, read a write-only device).


       20 ENOTDIR             Not a directory

                              This error occurs when a non-directory is speci‐
                              fied where a directory is required (for example,
                              in a path  prefix  or  as  an  argument  to  the
                              chdir(2) function).


       21 EISDIR              Is a directory

                              This  error  occurs  when  an attempt is made to
                              write on a directory.


       22 EINVAL              Invalid argument

                              This error occurs when an  invalid  argument  is
                              specified (for example, unmounting a non-mounted
                              device), mentioning an  undefined  signal  in  a
                              call  to  the signal(3C) or kill(2) function, or
                              an unsupported  operation  related  to  extended
                              attributes is attempted.


       23 ENFILE              File table overflow

                              This  error occurs when the system file table is
                              full (that is, SYS_OPEN files are open, and tem‐
                              porarily no more files can be opened).


       24 EMFILE              Too many open files

                              This  error occurs when no process may have more
                              than OPEN_MAX file descriptors open at a time.


       25 ENOTTY              Inappropriate ioctl for device

                              This error occurs when a call was  made  to  the
                              ioctl(2)  function specifying a file that is not
                              a special character device.


       26 ETXTBSY             Text file busy (obsolete)

                              This error occurs when an  attempt  is  made  to
                              execute  a  pure-procedure  program that is cur‐
                              rently open for writing. Also an attempt to open
                              for  writing  or to remove a pure-procedure pro‐
                              gram that is being executed. (This message is
                                            obsolete.)


       27 EFBIG               File too large

                              This error occurs when  the  size  of  the  file
                              exceeds   the   limit   specified   by  resource
                              RLIMIT_FSIZEn; the file size exceeds the maximum
                              supported  by  the file system; or the file size
                              exceeds the offset maximum of the file  descrip‐
                              tor.  See  the File Descriptor subsection of the
                              DEFINITIONS section below.


       28 ENOSPC              No space left on device

                              This error occurs  while  creating  a  directory
                              entry  or  writing an ordinary file, there is no
                              free space left on the device. In  the  fcntl(2)
                              function,  the  setting  or  removing  of record
                              locks on a file cannot be  accomplished  because
                              there  are  no  more  record entries left on the
                              system.


       29 ESPIPE              Illegal seek

                              This error occurs when a call  to  the  lseek(2)
                              function is issued to a pipe.


       30 EROFS               Read-only file system

                              This  error  occurs  when an attempt to modify a
                              file or directory is made on  a  device  mounted
                              read-only.


       31 EMLINK              Too many links

                              This  error  occurs an attempt to make more than
                              the maximum number  of  links,  LINK_MAX,  to  a
                              file.


       32 EPIPE               Broken pipe

                              This  error  occurs  when  a write on a pipe for
                              which there is no process to read the data. This
                              condition normally generates a signal; the error
                              is returned if the signal is ignored.


       33 EDOM                Math argument out of domain of function

                              This error occurs when the argument of  a  func‐
                              tion  in  the  math  package  (3M) is out of the
                              domain of the function.


       34 ERANGE              Math result not representable

                              This error occurs when the value of  a  function
                              in  the  math  package (3M) is not representable
                              within machine precision.


       35 ENOMSG              No message of desired type

                              This error occurs when an  attempt  is  made  to
                              receive  a message of a type that does not exist
                              on the specified message queue (see msgrcv(2)).


       36 EIDRM               Identifier removed

                              This error is returned to processes that  resume
                              execution  due  to  the removal of an identifier
                              from  the  file   system's   name   space   (see
                              msgctl(2), semctl(2), and shmctl(2)).


       37 ECHRNG              Channel number out of range


       38 EL2NSYNC            Level 2 not synchronized


       39 EL3HLT              Level 3 halted


       40 EL3RST              Level 3 reset


       41 ELNRNG              Link number out of range


       42 EUNATCH             Protocol driver not attached


       43 ENOCSI              No CSI structure available


       44 EL2HLT              Level 2 halted


       45 EDEADLK             Deadlock condition

                              This  error  occurs when a deadlock situation is
                              detected and avoided.  This  error  pertains  to
                              file  and  record  locking,  and also applies to
                              mutexes, semaphores,  condition  variables,  and
                              r/w locks.


       46 ENOLCK              No record locks available

                              This  error  occurs when there are no more locks
                              available. The system lock table  is  full  (see
                              fcntl(2)).


       47 ECANCELED           Operation canceled

                              This  error occurs when the associated asynchro‐
                              nous operation is canceled before completion.


       48 ENOTSUP             Not supported

                              This error occurs when this version of the  sys‐
                              tem  does  not  support the feature. Future ver‐
                              sions of the system may provide support.


       49 EDQUOT              Disc quota exceeded

                              A write(2) to an ordinary file, the creation  of
                              a directory or symbolic link, or the creation of
                              a directory  entry  failed  because  the  user's
                              quota of disk blocks was exhausted, or the allo‐
                              cation of an inode  for  a  newly  created  file
                              failed  because  the  user's quota of inodes was
                              exhausted.


       58-59                  Reserved


       60 ENOSTR              Device not a stream

                              A putmsg(2) or getmsg(2) call was attempted on a
                              file descriptor that is not a STREAMS device.


       61 ENODATA             No data available


       62 ETIME               Timer expired

                              This  error  occurs  when  the  timer  set for a
                              STREAMS ioctl(2) call has expired. The cause  of
                              this error is device-specific and could indicate
                              either a hardware or software failure,  or  per‐
                              haps  a  timeout value that is too short for the
                              specific operation. The status  of  the  ioctl()
                              operation   is   indeterminate.   This  is  also
                              returned in the case  of  _lwp_cond_timedwait(2)
                              or cond_timedwait(3C).


       63 ENOSR               Out of stream resources

                              During   a  STREAMS   open(2)  call,  either  no
                              STREAMS queues or no STREAMS  head  data  struc‐
                              tures were available. This is a temporary condi‐
                              tion; one may recover from it if other processes
                              release resources.


       65 ENOPKG              Package not installed

                              This  error  occurs  when users attempt to use a
                              call  from  a  package  which   has   not   been
                              installed.


       71 EPROTO              Protocol error

                              This  error  occurs  when  some  protocol  error
                              occurs. This error is  device-specific,  but  is
                              generally not related to a hardware failure.


       75 EADI                ADI mismatch detected

                              This  error  occurs when an ADI version mismatch
                              is detected when the system attempts to read  or
                              write  data  to  an ADI-enabled location that is
                              part of a buffer used for I/O.


       77 EBADMSG             Not a data message

                              During  a  read(2),   getmsg(2),   or   ioctl(2)
                              I_RECVFD call to a STREAMS device, something has
                              come to the head of the queue that  can  not  be
                              processed. That something depends on the call:

                              read():    control  information  or  passed file
                                         descriptor.


                              getmsg():  passed file descriptor.


                              ioctl():   control or data information.



       78 ENAMETOOLONG        File name too long

                              This error occurs when the length  of  the  path
                              argument  exceeds  PATH_MAX,  or the length of a
                              path   component    exceeds    NAME_MAX    while
                              _POSIX_NO_TRUNC   is   in   effect;   see   lim‐
                              its.h(3HEAD).


       79 EOVERFLOW           This error occurs when value is  too  large  for
                              defined data type.


       80 ENOTUNIQ            Name not unique on network

                              This  error  occurs when a given log name is not
                              unique.


       81 EBADFD              File descriptor in bad state

                              This error occurs when either a file  descriptor
                              refers to no open file or a read request is made
                              to a file that is open only for writing.


       82 EREMCHG             Remote address changed


       83 ELIBACC             Cannot access a needed share library

                              Trying to exec an a.out that requires  a  static
                              shared  library  and  the  static shared library
                              does not exist or the user does not have permis‐
                              sion to use it.


       84 ELIBBAD             Accessing a corrupted shared library

                              Trying  to  exec an a.out that requires a static
                              shared library (to be linked in) and exec  could
                              not  load  the static shared library. The static
                              shared library is probably corrupted.


       85 ELIBSCN             .lib section in a.out corrupted

                              Trying to exec an a.out that requires  a  static
                              shared  library  (to be linked in) and there was
                              erroneous data in the .lib section of the a.out.
                              The  .lib  section tells exec what static shared
                              libraries are needed. The a.out is probably cor‐
                              rupted.


       86 ELIBMAX             Attempting to link in more shared libraries than
                              system limit

                              Trying to  exec  an  a.out  that  requires  more
                              static  shared  libraries than is allowed on the
                              current configuration of the system.


       87 ELIBEXEC            Cannot exec a shared library directly

                              This error occurs while  attempting  to  exec  a
                              shared library directly.


       88 EILSEQ              Error 88

                              This  error occurs if there is am n illegal byte
                              sequence. Handle multiple characters as a single
                              character.


       89 ENOSYS              Operation not applicable


       90 ELOOP               Number of symbolic links encountered during path
                              name traversal exceeds MAXSYMLINKS


       91 ESTART              Restartable system call

                              This error occurs  when  an  interrupted  system
                              call should be restarted.


       92 ESTRPIPE            If pipe/FIFO, don't sleep in stream head

                              Streams pipe error (not externally visible).


       93 ENOTEMPTY           Directory not empty


       94 EUSERS              Too many users


       95 ENOTSOCK            Socket operation on non-socket


       96 EDESTADDRREQ        Destination address required

                              This  error  occurs  when  a required address is
                              omitted from an operation on  a  transport  end‐
                              point. Destination address is required.


       97 EMGSIZE             Message too long

                              This  error  occurs  when  a  message  sent on a
                              transport provider is larger than  the  internal
                              message buffer or some other network limit.


       98 EPROTOTYPE          Protocol wrong type for socket

                              This error occurs when a protocol specified does
                              not support the semantics  of  the  socket  type
                              requested.


       99 ENOPROTOOPT         Protocol not available

                              This  error occurs when a bad option or level is
                              specified when getting or setting options for  a
                              protocol.


       120 EPROTONOSUPPORT    Protocol not supported

                              The  protocol  has  not been configured into the
                              system or no implementation for it exists.


       121 ESOCKTNOSUPPORT    Socket type not supported

                              The support for the socket  type  has  not  been
                              configured  into the system or no implementation
                              for it exists.


       122 EOPNOTSUPP         Operation not supported on transport endpoint

                              For example, trying to accept a connection on  a
                              datagram transport endpoint.


       123 EPFNOSUPPORT       Protocol family not supported

                              The protocol family has not been configured into
                              the system or no implementation for  it  exists.
                              Used for the Internet protocols.


       124 EAFNOSUPPORT       Address family not supported by protocol family

                              This  error  occurs when an address incompatible
                              with the requested protocol is used.


       125 EADDRINUSE         Address already in use

                              This error occurs when a user attempts to use an
                              address  already  in  use, and the protocol does
                              not allow this.


       126 EADDRNOTAVAIL      Cannot assign requested address

                              Results from an attempt to  create  a  transport
                              endpoint  with  an  address  not  on the current
                              machine.


       127 ENETDOWN           Network is down

                              Operation encountered a dead network.


       128 ENETUNREACH        Network is unreachable

                              Operation was attempted to an  unreachable  net‐
                              work.


       129 ENETRESET          Network dropped connection because of reset

                              This  error  occurs  when  the host you are con‐
                              nected to crashes and reboots.


       130 ECONNABORTED       Software caused connection abort

                              A connection abort was caused internal  to  your
                              host machine.


       131 ECONNRESET         Connection reset by peer

                              A connection was forcibly closed by a peer. This
                              normally results from a loss of  the  connection
                              on the remote host due to a timeout or a reboot.


       132 ENOBUFS            No buffer space available

                              This  error occurs when an operation on a trans‐
                              port endpoint or pipe is not  performed  because
                              the  system  lacked  sufficient  buffer space or
                              because a queue is full.


       133 EISCONN            Transport endpoint is already connected

                              This error occurs when a connect request is made
                              on  an already connected transport endpoint; or,
                              a sendto() or sendmsg() request on  a  connected
                              transport  endpoint specified a destination when
                              already connected.


       134 ENOTCONN           Transport endpoint is not connected

                              This error occurs when  a  request  to  send  or
                              receive data is disallowed because the transport
                              endpoint is not connected and  (when  sending  a
                              datagram) no address was supplied.


       143 ESHUTDOWN          Cannot send after transport endpoint shutdown

                              This error occurs when a request to send data is
                              disallowed because the  transport  endpoint  has
                              already been shut down.


       144 ETOOMANYREFS       Too many references: cannot splice


       145 ETIMEDOUT          Connection timed out

                              This error occurs when a connect or send request
                              fails because the connected party does not prop‐
                              erly responds after a period of time; or a write
                              or fsync request fails because a file is  on  an
                              NFS file system mounted with the soft option.


       146 ECONNREFUSED       Connection refused

                              This  error  occurs  when no connection could be
                              made because the target machine actively refused
                              it.  This usually results from trying to connect
                              to a service that  is  inactive  on  the  remote
                              host.


       147 EHOSTDOWN          Host is down

                              This  error  occurs  when  a  transport provider
                              operation fails because the destination host  is
                              down.


       148 EHOSTUNREACH       No route to host

                              This  error  occurs  when  a  transport provider
                              operation is attempted to an unreachable host.


       149 EALREADY           Operation already in progress

                              This error occurs when an operation is attempted
                              on  a  non-blocking  object  that already has an
                              operation in progress.


       150 EINPROGRESS        Operation now in progress

                              This error occurs when an operation that takes a
                              long  time  to complete (such as a connect()) is
                              attempted on a non-blocking object.


       151 ESTALE             Stale NFS file handle


DEFINITIONS
   Background Process Group
       Any process group that is not the foreground process group of a session
       that has established a connection with a controlling terminal.

   Controlling Process
       A  session leader that established a connection to a controlling termi‐
       nal.

   Controlling Terminal
       A terminal that is associated with a session. Each session may have, at
       most,  one  controlling  terminal  associated with it and a controlling
       terminal may  be  associated  with  only  one  session.  Certain  input
       sequences  from  the  controlling  terminal cause signals to be sent to
       process groups in the session associated with the controlling terminal.
       For more information, see the termio(4I) man page.

   Directory
       Directories organize files into a hierarchical system where directories
       are the nodes in the hierarchy. A directory is a file that catalogs the
       list  of  files,  including  directories  (sub-directories),  that  are
       directly beneath it in the hierarchy. Entries in a directory  file  are
       called  links.  A link associates a file identifier with a filename. By
       convention, a directory contains at least two links,  .  (dot)  and  ..
       (dot-dot).  The  link  called  dot refers to the directory itself while
       dot-dot refers to its parent directory. The root  directory,  which  is
       the top-most node of the hierarchy, has itself as its parent directory.
       The pathname of the root directory is / and the parent directory of the
       root directory is /.

   Downstream
       The direction from the stream head to the driver in a stream.

   Driver
       In a stream, the driver provides the interface between peripheral hard‐
       ware and the stream. A driver can also be a pseudo-driver,  such  as  a
       multiplexor or log driver (see log(4D)), which is not associated with a
       hardware device.

   Effective User ID and Effective Group ID
       An active process has an effective user ID and an  effective  group  ID
       that  are  used  to  determine file access permissions (see below). The
       effective user ID and effective group ID are  equal  to  the  process's
       real user ID and real group ID, respectively, unless the process or one
       of its ancestors evolved from a file that had the  set-user-ID  bit  or
       set-group-ID bit set (see exec(2)).

   File Access Permissions
       Read, write, and execute/search permissions for a file are granted to a
       process if one or more of the following conditions are true:

           o      The effective user ID of the process matches the user ID  of
                  the  owner of the file and the appropriate access bit of the
                  "owner" portion (0700) of the file mode is set.


           o      The effective user ID of the process does not match the user
                  ID  of the owner of the file, but either the effective group
                  ID or one of the supplementary  group  IDs  of  the  process
                  match  the  group  ID of the file and the appropriate access
                  bit of the "group" portion (0070) of the file mode is set.


           o      The effective user ID of the process does not match the user
                  ID of the owner of the file, and neither the effective group
                  ID nor any of the supplementary group  IDs  of  the  process
                  match  the  group ID of the file, but the appropriate access
                  bit of the "other" portion (0007) of the file mode is set.


           o      The read, write, or execute mode bit  is  not  set  but  the
                  process has the discretionary file access override privilege
                  for the corresponding mode bit: {PRIV_FILE_DAC_READ} for the
                  read   bit   {PRIV_FILE_DAC_WRITE}   for   the   write  bit,
                  {PRIV_FILE_DAC_SEARCH} for the execute bit  on  directories,
                  and  {PRIV_FILE_DAC_EXECUTE} for the executable bit on plain
                  files.



       Otherwise, the corresponding permissions are denied.

   File Descriptor
       A file descriptor is a small integer used to perform I/O operations  on
       a  file.  The  value  of  a file descriptor is from 0 to (NOFILES−1). A
       process may have no more than NOFILES file descriptors open  simultane‐
       ously.  A  file  descriptor  is  returned  by  calls such as open(2) or
       pipe(2). The file descriptor is used as an argument by  calls  such  as
       read(2), write(2), ioctl(2), and close(2).


       Each  file  descriptor  has a corresponding offset maximum. For regular
       files that are opened without setting the O_LARGEFILE flag, the  offset
       maximum is 2 Gbyte − 1 byte (2^31 −1 bytes). For regular files that are
       opened with the O_LARGEFILE flag set, the offset  maximum  is  2^63  −1
       bytes.

   File Name
       Names  consisting of 1 to NAME_MAX characters are used to name an ordi‐
       nary file, special file or directory.


       These characters are selected from the  set  of  all  character  values
       excluding \0 (null) and the ASCII code for / (slash).


       Note  that  it is generally unwise to use *, ?, [, or ] as part of file
       names because of the special meaning attached to  these  characters  by
       the  shell (see sh(1), csh(1), and ksh(1)). Although permitted, the use
       of unprintable characters in file names should be avoided.


       A file name is sometimes referred  to  as  a  pathname  component.  The
       interpretation  of  a  pathname component is dependent on the values of
       NAME_MAX and _POSIX_NO_TRUNC associated with the path  prefix  of  that
       component.   If   any  pathname  component  longer  than  NAME_MAX  and
       _POSIX_NO_TRUNC is in effect for the path prefix of that component (see
       fpathconf(2) and limits.h(3HEAD)), it shall be considered an error con‐
       dition in that implementation. Otherwise, the implementation shall  use
       the first NAME_MAX bytes of the pathname component.

   Foreground Process Group
       Each  session that has established a connection with a controlling ter‐
       minal will distinguish one process group of the session  as  the  fore‐
       ground  process  group of the controlling terminal. This group has cer‐
       tain privileges when accessing its controlling terminal that are denied
       to background process groups.

   {IOV_MAX}
       Maximum number of entries in a struct iovec array.

   {LIMIT}
       The  braces notation, {LIMIT}, is used to denote a magnitude limitation
       imposed by the implementation. This indicates  a  value  which  may  be
       defined  by a header file (without the braces), or the actual value may
       be obtained at runtime by a call to  the  configuration  inquiry  path‐
       conf(2) with the name argument _PC_LIMIT.

   Masks
       The file mode creation mask of the process used during any create func‐
       tion calls to turn off permission bits in the mode  argument  supplied.
       Bit  positions  that are set in umask(cmask) are cleared in the mode of
       the created file.

   Message
       In a stream, one or more blocks of data or information, with associated
       STREAMS  control  structures. Messages can be of several defined types,
       which identify the message contents. Messages are  the  only  means  of
       transferring data and communicating within a stream.

   Message Queue
       In  a stream, a linked list of messages awaiting processing by a module
       or driver.

   Message Queue Identifier
       A message queue identifier (msqid) is a unique positive integer created
       by  a  msgget(2) call. Each msqid has a message queue and a data struc‐
       ture associated with it. The data structure is referred to as  msqid_ds
       and contains the following members:

         struct     ipc_perm msg_perm;
         struct     msg *msg_first;
         struct     msg *msg_last;
         ulong_t    msg_cbytes;
         ulong_t    msg_qnum;
         ulong_t    msg_qbytes;
         pid_t      msg_lspid;
         pid_t      msg_lrpid;
         time_t     msg_stime;
         time_t     msg_rtime;
         time_t     msg_ctime;



       The following information describes the msqid_ds structure members:


       The msg_perm member is an ipc_perm structure that specifies the message
       operation permission (see below). This structure includes the following
       members:

         uid_t    cuid;   /* creator user id */
         gid_t    cgid;   /* creator group id */
         uid_t    uid;    /* user id */
         gid_t    gid;    /* group id */
         mode_t   mode;   /* r/w permission */
         ulong_t  seq;    /* slot usage sequence # */
         key_t    key;    /* key */



       The *msg_first member is a pointer to the first message on the queue.


       The *msg_last member is a pointer to the last message on the queue.


       The msg_cbytes member is the current number of bytes on the queue.


       The msg_qnum member is the number of messages currently on the queue.


       The  msg_qbytes  member  is  the maximum number of bytes allowed on the
       queue.


       The msg_lspid member is the process ID of the last  process  that  per‐
       formed a msgsnd() operation.


       The  msg_lrpid  member  is the process id of the last process that per‐
       formed a msgrcv() operation.


       The msg_stime member is the time of the last msgsnd() operation.


       The msg_rtime member is the time of the last msgrcv() operation.


       The msg_ctime member is the time of the last  msgctl()  operation  that
       changed a member of the above structure.

   Message Operation Permissions
       In the msgctl(2), msgget(2), msgrcv(2), and msgsnd(2) function descrip‐
       tions, the permission required for an operation is  given  as  {token},
       where token is the type of permission needed, interpreted as follows:

         00400   READ by user
         00200   WRITE by user
         00040   READ by group
         00020   WRITE by group
         00004   READ by others
         00002   WRITE by others



       Read  and write permissions for a msqid are granted to a process if one
       or more of the following conditions are true:

           o      The {PRIV_IPC_DAC_READ} or {PRIV_IPC_DAC_WRITE} privilege is
                  present in the effective set.


           o      The  effective  user ID of the process matches msg_perm.cuid
                  or msg_perm.uid in the data structure associated with  msqid
                  and  the  appropriate  bit  of  the "user" portion (0600) of
                  msg_perm.mode is set.


           o      Any group ID in the process credentials from the set matches
                  msg_perm.cgid or msg_perm.gid and the appropriate bit of the
                  "group" portion (060) of msg_perm.mode is set.


           o      The  appropriate  bit  of  the  "other"  portion  (006)   of
                  msg_perm.mode is set."



       Otherwise, the corresponding permissions are denied.

   Module
       A module is an entity containing processing routines for input and out‐
       put data. It always exists in the  middle  of  a  stream,  between  the
       stream's  head and a driver. A module is the STREAMS counterpart to the
       commands in a shell pipeline except that a module contains  a  pair  of
       functions   which   allow  independent  bidirectional  (downstream  and
       upstream) data flow and processing.

   Multiplexor
       A multiplexor is a driver that allows streams associated  with  several
       user  processes  to be connected to a single driver, or several drivers
       to be connected to a single user process. STREAMS does  not  provide  a
       general  multiplexing  driver, but does provide the facilities for con‐
       structing  them  and  for  connecting  multiplexed  configurations   of
       streams.

   Offset Maximum
       An  offset  maximum  is an attribute of an open file description repre‐
       senting the largest value that can be used as a file offset.

   Orphaned Process Group
       A process group in which the parent of every member  in  the  group  is
       either  itself a member of the group, or is not a member of the process
       group's session.

   Path Name
       A path name is a null-terminated  character  string  starting  with  an
       optional  slash (/), followed by zero or more directory names separated
       by slashes, optionally followed by a file name.


       If a path name begins with a slash, the path search begins at the  root
       directory. Otherwise, the search begins from the current working direc‐
       tory.


       A slash by itself names the root directory.


       Unless specifically stated otherwise, the null path name is treated  as
       if it named a non-existent file.

   Privileged User
       Solaris  software  implements  a  set  of privileges that provide fine-
       grained control over the actions of processes. The possession of a cer‐
       tain privilege allows a process to perform a specific set of restricted
       operations. Prior to the Oracle Solaris 10 release, a  process  running
       with uid 0 was granted all privileges. See privileges(7) for the seman‐
       tics and the degree of backward compatibility awarded to processes with
       an effective uid of 0.

   Process ID
       Each  process  in the system is uniquely identified during its lifetime
       by a positive integer called a process  ID.  A  process  ID  cannot  be
       reused  by  the  system until the process lifetime, process group life‐
       time, and session lifetime ends for any process ID, process  group  ID,
       and  session  ID  equal  to that process ID. There are threads within a
       process with thread IDs thread_t and LWPID_t.  These  threads  are  not
       visible to the outside process.

   Parent Process ID
       A  new  process is created by a currently active process (see fork(2)).
       The parent process ID of a process is the process ID of its creator.

   Privilege
       Having appropriate privileges means having the capability  to  override
       system restrictions.

   Process Group
       Each process in the system is a member of a process group that is iden‐
       tified by a process group ID. Any process that is not a  process  group
       leader  may  create  a  new  process  group  and become its leader. Any
       process that is not a process group leader may join an existing process
       group  that  shares  the  same  session as the process. A newly created
       process joins the process group of its parent.

   Process Group Leader
       A process group leader is a process whose process ID is the same as its
       process group ID.

   Process Group ID
       Each active process is a member of a process group and is identified by
       a positive integer called the process group ID. This ID is the  process
       ID  of the group leader. This grouping permits the signaling of related
       processes (for more information, see kill(2) man page).

   Process Lifetime
       A process lifetime begins when the process is forked and ends after  it
       exits,  when  its  termination  has  been  acknowledged  by  its parent
       process. For more information, see wait(3C) man page.

   Process Group Lifetime
       A process group lifetime begins when the process group  is  created  by
       its  process  group  leader,  and  ends  when  the lifetime of the last
       process in the group ends or when the last process in the group  leaves
       the group.

   Processor Set ID
       The  processors  in a system may be divided into subsets, known as pro‐
       cessor sets. A process bound to one of these sets will run only on pro‐
       cessors  in  that  set, and the processors in the set will normally run
       only processes that have been bound to the set. Each  active  processor
       set  is  identified  by  a  positive integer. For more information, see
       pset_create(2) man page.

   Read Queue
       In a stream, the message queue in a module or  driver  containing  mes‐
       sages moving upstream.

   Real User ID and Real Group ID
       Each  user allowed on the system is identified by a positive integer (0
       to MAXUID) called a real user ID.


       Each user is also a member of a group. The group  is  identified  by  a
       positive integer called the real group ID.


       An  active process has a real user ID and real group ID that are set to
       the real user ID and real group ID, respectively, of the user responsi‐
       ble for the creation of the process.

   Root Directory and Current Working Directory
       Each process has associated with it a concept of a root directory and a
       current working directory  for  the  purpose  of  resolving  path  name
       searches.  The  root directory of a process need not be the root direc‐
       tory of the root file system.

   Saved Resource Limits
       Saved resource limits is an attribute of a process that  provides  some
       flexibility  in  the  handling  of  unrepresentable resource limits, as
       described in the exec family of functions and setrlimit(2).

   Saved User ID and Saved Group ID
       The saved user ID and saved group ID are the values  of  the  effective
       user  ID  and effective group ID just after an exec of a file whose set
       user or set group file mode bit has been set (see exec(2)).

   Semaphore Identifier
       A semaphore identifier (semid) is a unique positive integer created  by
       a  semget(2) call. Each semid has a set of semaphores and a data struc‐
       ture associated with it. The data structure is referred to as  semid_ds
       and contains the following members:

         struct ipc_perm   sem_perm;    /* operation permission struct */
         struct sem        *sem_base;   /* ptr to first semaphore in set */
         ushort_t          sem_nsems;   /* number of sems in set */
         time_t            sem_otime;   /* last operation time */
         time_t            sem_ctime;   /* last change time */
                                        /* Times measured in secs since */
                                        /* 00:00:00 GMT, Jan. 1, 1970 */



       The following are descriptions of the semid_ds structure members:


       The  sem_perm  member is an ipc_perm structure that specifies the sema‐
       phore operation permission (see below).  This  structure  includes  the
       following members:

         uid_t     uid;    /* user id */
         gid_t     gid;    /* group id */
         uid_t     cuid;   /* creator user id */
         gid_t     cgid;   /* creator group id */
         mode_t    mode;   /* r/a permission */
         ulong_t   seq;    /* slot usage sequence number */
         key_t     key;    /* key */



       The  sem_nsems  member is equal to the number of semaphores in the set.
       Each semaphore in the  set  is  referenced  by  a  nonnegative  integer
       referred to as a sem_num. sem_num values run sequentially from 0 to the
       value of sem_nsems minus 1.


       The sem_otime member is the time of the last semop(2) operation.


       The sem_ctime member is the time of the last semctl(2)  operation  that
       changed a member of the above structure.


       A  semaphore is a data structure called sem that contains the following
       members:

         ushort_t   semval;    /* semaphore value */
         pid_t      sempid;    /* pid of last operation  */
         ushort_t   semncnt;   /* # awaiting semval > cval */
         ushort_t   semzcnt;   /* # awaiting semval = 0 */



       The following information describes the sem structure members:


       The semval member is a non-negative integer that is the actual value of
       the semaphore.


       The  sempid  member is equal to the process ID of the last process that
       performed a semaphore operation on this semaphore.


       The semncnt member is a count of the number of processes that are  cur‐
       rently  suspended  awaiting  this  semaphore's semval to become greater
       than its current value.


       The semzcnt member is a count of the number of processes that are  cur‐
       rently suspended awaiting this semaphore's semval to become 0.

   Semaphore Operation Permissions
       In  the  semop(2)  and  semctl(2) function descriptions, the permission
       required for an operation is given as {token}, where token is the  type
       of permission needed interpreted as follows:

         00400       READ by user
         00200   ALTER by user
         00040   READ by group
         00020   ALTER by group
         00004   READ by others
         00002   ALTER by others



       Read  and alter permissions for a semid are granted to a process if one
       or more of the following conditions are true:

           o      The {PRIV_IPC_DAC_READ} or {PRIV_IPC_DAC_WRITE} privilege is
                  present in the effective set.


           o      The  effective  user ID of the process matches sem_perm.cuid
                  or sem_perm.uid in the data structure associated with  semid
                  and  the  appropriate  bit  of  the "user" portion (0600) of
                  sem_perm.mode is set.


           o      The effective group ID of the process matches  sem_perm.cgid
                  or  sem_perm.gid and the appropriate bit of the "group" por‐
                  tion (060) of sem_perm.mode is set.


           o      The  appropriate  bit  of  the  "other"  portion   (06)   of
                  sem_perm.mode is set.



       Otherwise, the corresponding permissions are denied.

   Session
       A  session  is  a group of processes identified by a common ID called a
       session ID, capable of establishing a  connection  with  a  controlling
       terminal.  Any  process that is not a process group leader may create a
       new session and process group, becoming the session leader of the  ses‐
       sion  and  process  group  leader of the process group. A newly created
       process joins the session of its creator.

   Session ID
       Each session in the system is uniquely identified during  its  lifetime
       by  a  positive integer called a session ID, the process ID of its ses‐
       sion leader.

   Session Leader
       A session leader is a process whose session  ID  is  the  same  as  its
       process and process group ID.

   Session Lifetime
       A  session  lifetime  begins when the session is created by its session
       leader, and ends when the lifetime of the last process that is a member
       of  the  session ends, or when the last process that is a member in the
       session leaves the session.

   Shared Memory Identifier
       A shared memory identifier (shmid) is a unique positive integer created
       by  a shmget(2) or shmget_osm(2) call. Each shmid has a segment of mem‐
       ory (referred to as a shared memory segment) and a data structure asso‐
       ciated with it. (Note that these shared memory segments must be explic‐
       itly removed by the user after the last reference to them is  removed.)
       The  data structure is referred to as shmid_ds and contains the follow‐
       ing members:

         struct ipc_perm   shm_perm;     /* operation permission struct */
         size_t            shm_segsz;    /* size of segment */
         struct anon_map   *shm_amp;     /* ptr to region structure */
         char              pad[4];       /* for swap compatibility */
         pid_t             shm_lpid;     /* pid of last operation */
         pid_t             shm_cpid;     /* creator pid */
         uintptr_t         shm_flags;    /* see below */
         uint64_t          shm_gransize; /* shared memory granule size */
         uint64_t          shm_allocated;/* shared memory amount allocated */
         shmatt_t          shm_nattch;   /* number of current attaches */
         ulong_t           shm_cnattch;  /* used only for shminfo */
         time_t            shm_atime;    /* last attach time */
         time_t            shm_dtime;    /* last detach time */
         time_t            shm_ctime;    /* last change time */
                                         /* Times measured in secs since */
                                         /* 00:00:00 GMT, Jan. 1, 1970 */



       The following information describes the shmid_ds structure members:


       The shm_perm member is an ipc_perm structure that specifies the  shared
       memory  operation  permission  (see below). This structure includes the
       following members:

         uid_t     cuid;   /* creator user id */
         gid_t     cgid;   /* creator group id */
         uid_t     uid;    /* user id */
         gid_t     gid;    /* group id */
         mode_t    mode;   /* r/w permission */
         ulong_t   seq;    /* slot usage sequence # */
         key_t     key;    /* key */



       The shm_segsz member specifies the size of the shared memory segment in
       bytes.


       The  shm_cpid  member is the process ID of the process that creates the
       shared memory identifier.


       The shm_lpid member is the process ID of the  last  process  that  per‐
       formed a shmat() or shmdt() operation (see shmop(2)).


       If shm_flags has the SHMDS_GRANULE bit set, then the shared memory seg‐
       ment  was  created  using  shmget_osm(2),  and  the  shm_gransize   and
       shm_allocated  members  are valid. The shm_gransize member contains the
       allocation granule for the segment, and the shm_allocated  member  con‐
       tains  the  amount of memory allocated inside the segment. If shm_flags
       does not have the SHMDS_GRANULE bit  set,  then  the  shm_gransize  and
       shm_allocated members have undefined contents.


       The  shm_nattch  member  is the number of processes that currently have
       this segment attached.


       The shm_atime member is the time of the  last  shmat()  operation  (for
       more information, see shmop(2) man page).


       The  shm_dtime  member  is  the time of the last shmdt() operation (for
       more information, see shmop(2) man page).


       The shm_ctime member is the time of the last shmctl(2)  operation  that
       changed one of the members of the above structure.

   Shared Memory Operation Permissions
       In the shmctl(2), shmat(), and shmdt() (see shmop(2)) function descrip‐
       tions, the permission required for an operation is  given  as  {token},
       where  token  is the type of permission needed and it is interpreted as
       follows:

         00400   READ by user
         00200   WRITE by user
         00040   READ by group
         00020   WRITE by group
         00004   READ by others
         00002   WRITE by others



       Read and write permissions for a shmid are granted to a process if  one
       or more of the following conditions are true:

           o      The {PRIV_IPC_DAC_READ} or {PRIV_IPC_DAC_WRITE} privilege is
                  present in the effective set.


           o      The effective user ID of the process  matches  shm_perm.cuid
                  or  shm_perm.uid in the data structure associated with shmid
                  and the appropriate bit of  the  "user"  portion  (0600)  of
                  shm_perm.mode is set.


           o      The  effective group ID of the process matches shm_perm.cgid
                  or shm_perm.gid and the appropriate bit of the "group"  por‐
                  tion (060) of shm_perm.mode is set.


           o      The   appropriate   bit  of  the  "other"  portion  (06)  of
                  shm_perm.mode is set.



       Otherwise, the corresponding permissions are denied.

   Special Processes
       The process with ID 0 and the process with ID 1 are  special  processes
       referred  to  as  proc0  and  proc1;  see kill(2). proc0 is the process
       scheduler. proc1 is the initialization process  (init);  proc1  is  the
       ancestor  of  every  other process in the system and is used to control
       the process structure.

   STREAMS
       A set of kernel mechanisms that support the development of network ser‐
       vices  and  data  communication drivers. It defines interface standards
       for character I/O within the kernel and between  the  kernel  and  user
       level processes. The STREAMS mechanism is composed of utility routines,
       kernel facilities, and a set of data structures.

   Stream
       A stream is a full-duplex data path within the kernel  between  a  user
       process  and  driver routines. The primary components of a stream are a
       stream head, a driver, and zero or more modules between the stream head
       and driver. A stream is analogous to a shell pipeline, except that data
       flow and processing are bidirectional.

   Stream Head
       In a stream, the stream head is the end of the stream that provides the
       interface  between  the  stream and a user process. The principal func‐
       tions of the stream head are processing  STREAMS-related  system  calls
       and passing data and information between a user process and the stream.

   Upstream
       The direction from driver to stream head in a stream.

   Write Queue
       In  a  stream,  the message queue in a module or driver containing mes‐
       sages moving downstream.

ACKNOWLEDGMENTS
       Oracle America, Inc. gratefully acknowledges The Open Group for permis‐
       sion  to  reproduce portions of its copyrighted documentation. Original
       documentation  from  The  Open  Group  can  be   obtained   online   at
       http://www.opengroup.org/bookstore/.


       The  Institute  of  Electrical  and  Electronics Engineers and The Open
       Group, have given us permission to reprint portions of their documenta‐
       tion.


       In the following statement, the phrase ``this text'' refers to portions
       of the system documentation.


       Portions of this text are reprinted and reproduced in  electronic  form
       in the Oracle Solaris Reference Manual, from IEEE Std 1003.1, 2004 Edi‐
       tion, Standard for Information Technology -- Portable Operating  System
       Interface  (POSIX),  The  Open Group Base Specifications Issue 6, Copy‐
       right (C) 2001-2004 by the  Institute  of  Electrical  and  Electronics
       Engineers,  Inc  and  The  Open  Group. In the event of any discrepancy
       between these versions and the original IEEE and The Open  Group  Stan‐
       dard, the original IEEE and The Open Group Standard is the referee doc‐
       ument. The original Standard can be obtained online at http://www.open‐
       group.org/standards/unix.


       This notice shall appear on any product containing this material.

SEE ALSO
       standards(7), threads(7)



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