Intro(2) manual page
Table of Contents
Intro, intro - introduction to system calls and error numbers
#include <errno.h>
This section describes all of the system calls.
Most of these calls have one or more error returns. An error condition is
indicated by an otherwise impossible returned value. This is almost always
-1 or the null pointer; the individual descriptions specify the details.
An error number is also made available in the external variable errno. errno
is not cleared on successful calls, so it should be tested only after an
error has been indicated.
In the case of multithreaded applications, the
_REENTRANT
flag must be defined on the command line at compilation time
(-D_REENTRANT
). When the _REENTRANT
flag is defined, errno becomes a macro
which enables each thread to have its own errno. This errno macro can be
used on either side of the assignment , just as if it were a variable.
Applications should use bound threads rather than the _lwp_* system
calls (see thr_create(3t)
). Using LWP
s directly is not advised because
libraries are only safe to use with threads, not LWP
s.
Each system call
description attempts to list all possible error numbers. The following is
a complete list of the error numbers and their names as defined in <errno.h>.
- 1 EPERM Not super-user
Typically this error indicates an attempt to modify a file in some way
forbidden except to its owner or the super-user. It is also returned for
attempts by ordinary users to do things allowed only to the super-user.
- 2
ENOENT No such file or directory
A file name is specified and the file should exist but doesn’t, or one
of the directories in a path name does not exist.
- 3 ESRCH No such process,
LWP, or thread
No process can be found in the system that corresponds to the specified
PID, LWPID_t, or thread_t.
- 4 EINTR Interrupted system call
An asynchronous signal (such as interrupt or quit), which the user has
elected to catch, occurred during a system service routine. If execution
is resumed after processing the signal, it will appear as if the interrupted
routine call returned this error condition. - In a multi-threaded 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. This error may in some cases occur
on a call following the one to which it actually applies.
- 6 ENXIO No
such device or address
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
An argument list longer than ARG_MAX
bytes is presented to a member
of the exec family of routines. The argument list limit is the sum of the
size of the argument list plus the size of the environment’s exported shell
variables.
- 8 ENOEXEC Exec format error
A request is made to execute a file which, although it has the appropriate
permissions, does not start with a valid format (see a.out(4)
).
- 9 EBADF
Bad file number
Either a file descriptor refers to no open file, or a read (respectively,
write) request is made to a file that is open only for writing (respectively,
reading).
- 10 ECHILD No child processes
A wait routine was executed by a process that had no existing or unwaited-for
child processes.
- 11 EAGAIN No more processes, or no more LWPs
For example, the fork routine failed because the system’s process table
is full or the user is not allowed to create any more processes, or a system
call failed because of insufficient memory or swap space.
- 12 ENOMEM Not
enough space
During execution of an exec, brk, or sbrk routine, a program asks for
more space than the system is able to supply. This is not a temporary 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 routine. If this error occurs on a resource associated with Remote
File Sharing (RFS), it indicates a memory depletion which may be temporary,
dependent on system activity at the time the call was invoked.
- 13 EACCES
Permission denied
An attempt was made to access a file in a way forbidden by the protection
system.
- 14 EFAULT Bad address
The system encountered 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. Because systems will 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.
- 15 ENOTBLK
Block device required
A non-block device or file was mentioned where a block device was required
(for example, in a call to the mount routine).
- 16 EBUSY Device busy
An attempt was made to mount a device that was already mounted or an attempt
was made to unmount a device on which there is an active file (open file,
current directory, mounted-on file, active text segment). 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, condition variables, and r/w locks, to indicate that a lock
is held. And, EBUSY
is also used by the processor control function P_ONLINE
.
- 17 EEXIST File exists
An existing file was mentioned in an inappropriate context (for example,
call to the link routine).
- 18 EXDEV Cross-device link
A hard link to a file on another device was attempted.
- 19 ENODEV No
such device
An attempt was made to apply an inappropriate operation to a device (for
example, read a write-only device).
- 20 ENOTDIR Not a directory
A non-directory was specified where a directory is required (for example,
in a path prefix or as an argument to the chdir routine).
- 21 EISDIR
Is a directory
An attempt was made to write on a directory.
- 22 EINVAL Invalid argument
An invalid argument was specified (for example, unmounting a non-mounted
device), mentioning an undefined signal in a call to the signal or kill
routine.
- 23 ENFILE File table overflow
The system file table is full (that is, SYS_OPEN
files are open, and
temporarily no more files can be opened).
- 24 EMFILE Too many open files
No process may have more than OPEN_MAX
file descriptors open at a time.
- 25 ENOTTY Inappropriate ioctl for device
A call was made to the ioctl routine specifying a file that is not a special
character device.
- 26 ETXTBSY Text file busy (obsolete)
An attempt was made to execute a pure-procedure program that is currently
open for writing. Also an attempt to open for writing or to remove a pure-procedure
program that is being executed. (This message is obsolete.)
- 27 EFBIG
File too large
The size of the file exceeded the limit specified by resource RLIMIT_FSIZE
;
or, the file size exceeds the maximum supported by the file system.
- 28 ENOSPC No space left on device
While writing an ordinary file or creating a directory entry, there is
no free space left on the device. In the fcntl routine, 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
A call to the lseek routine was issued to a pipe.
- 30 EROFS Read-only
file system
An attempt to modify a file or directory was made on a device mounted
read-only.
- 31 EMLINK Too many links
An attempt to make more than the maximum number of links, LINK_MAX
, to
a file.
- 32 EPIPE Broken pipe
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 func
The argument of a function in the math package (3M)
is out of the domain
of the function.
- 34 ERANGE Math result not representable
The value of a function in the math package (3M)
is not representable
within machine precision.
- 35 ENOMSG No message of desired type
An attempt was made to receive a message of a type that does not exist
on the specified message queue (see msgop(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
A deadlock situation was 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
There are no more locks available. The system lock table is full (see fcntl(2)
).
- 47 ECANCELED Operation canceled
The associated asynchronous operation was canceled before completion.
- 48
ENOTSUP Not supported
This version of the system does not support this feature. Future versions
of the system may provide support.
- 49 EDQUOT Disc quota exceeded
A write() 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 allocation 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 or getmsg system call was attempted on a file descriptor that
is not a STREAMS
device.
- 61 ENODATA No data available
- 62 ETIME Timer expired
The timer set for a STREAMS
ioctl call has expired. The cause of this error
is device specific and could indicate either a hardware or software failure,
or perhaps 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() or cond_timedwait().
- 63 ENOSR
Out of stream resources
During a STREAMS
open, either no STREAMS
queues or no STREAMS
head
data structures were available. This is a temporary condition; one may recover
from it if other processes release resources.
- 64 ENONET Machine is not
on the network
This error is Remote File Sharing (RFS) specific. It occurs when users
try to advertise, unadvertise, mount, or unmount remote resources while
the machine has not done the proper startup to connect to the network.
- 65
ENOPKG Package not installed
This error occurs when users attempt to use a system call from a package
which has not been installed.
- 66 EREMOTE Object is remote
This error is RFS specific. It occurs when users try to advertise a resource
which is not on the local machine, or try to mount/unmount a device (or
pathname) that is on a remote machine.
- 67 ENOLINK Link has been severed
This error is RFS specific. It occurs when the link (virtual circuit) connecting
to a remote machine is gone.
- 68 EADV Advertise error
This error is RFS specific. It occurs when users try to advertise a resource
which has been advertised already, or try to stop RFS while there are resources
still advertised, or try to force unmount a resource when it is still advertised.
- 69 ESRMNT Srmount error
This error is RFS specific. It occurs when an attempt is made to stop RFS
while resources are still mounted by remote machines, or when a resource
is readvertised with a client list that does not include a remote machine
that currently has the resource mounted.
- 70 ECOMM Communication error on send
This error is RFS specific. It occurs when the current process is waiting
for a message from a remote machine, and the virtual circuit fails.
- 71
EPROTO Protocol error
Some protocol error occurred. This error is device specific, but is generally
not related to a hardware failure.
- 74 EMULTIHOP Multihop attempted
This error is RFS specific. It occurs when users try to access remote
resources which are not directly accessible.
- 76 EDOTDOT Error 76
This error is RFS specific. A way for the server to tell the client that
a process has transferred back from mount point.
- 77 EBADMSG Not a data message
During a read, getmsg, or ioctl I_RECVFD
system call to a STREAMS
device,
something has come to the head of the queue that can’t be processed. That
something depends on the system call: read: control information or passed
file descriptor.
getmsg: passed file descriptor.
ioctl: control or data information.
- 78 ENAMETOOLONG File name too long
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 limits(4)
.
- 79 EOVERFLOW
Value too large for defined data type.
- 80 ENOTUNIQ Name not unique on
network
Given log name not unique.
- 81 EBADFD File descriptor in bad state
Either a file descriptor refers to no open file or a read request was
made to a file that is open only for writing.
- 82 EREMCHG Remote address
changed
- 83 ELIBACC
Trying to exec an a.out that requires a static shared library and the static
shared library doesn’t exist or the user doesn’t have permission 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 corrupted.
- 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. See
- 87 ELIBEXEC
Cannot exec a shared library directly
Attempting to exec a shared library directly.
- 88 EILSEQ Error 88
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
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
A required address was omitted from an operation on a transport endpoint.
Destination address required.
- 97 EMSGSIZE Message too long
A message sent on a transport provider was larger than the internal message
buffer or some other network limit.
- 98 EPROTOTYPE Protocol wrong type
for socket
A protocol was specified that does not support the semantics of the socket
type requested.
- 99 ENOPROTOOPT Protocol not available
A bad option or level was 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
An address incompatible with the requested protocol was used.
- 125 EADDRINUSE
Address already in use
User attempted 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 network.
- 129 ENETRESET Network
dropped connection because of reset
The host you were connected to crashed and rebooted.
- 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
An operation on a transport endpoint or pipe was not performed because
the system lacked sufficient buffer space or because a queue was full.
- 133
EISCONN Transport endpoint is already connected
A connect request was 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
A request to send or receive data was 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
A request to send data was disallowed because the transport endpoint has
already been shut down.
- 144 ETOOMANYREFS Too many references: cannot
splice
- 145 ETIMEDOUT Connection timed out
A connect or send request failed because the connected party did not properly
respond after a period of time. (The timeout period is dependent on the
communication protocol.)
- 146 ECONNREFUSED Connection refused
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
A transport provider operation failed because the destination host was
down.
- 148 EHOSTUNREACH No route to host
A transport provider operation was attempted to an unreachable host.
- 149 EALREADY Operation already in progress
An operation was attempted on a non-blocking object that already had an
operation in progress.
- 150 EINPROGRESS Operation now in progress
An operation that takes a long time to complete (such as a connect) was
attempted on a non-blocking object.
- 151 ESTALE Stale NFS file handle
Any process group that is not the foreground
process group of a session that has established a connection with a controlling
terminal.
A session leader that established a connection
to a 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; see termio(7I)
.
Directories organize files
into a hierarchical system where directories are the nodes in the hierarchy.
A directory is a file that catalogues 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 /.
In a stream, the direction from stream head to
driver.
In a stream, the driver provides the interface between peripheral
hardware and the stream. A driver can also be a pseudo-driver, such as a
multiplexor or log driver (see log(7D)
), which is not associated with a
hardware device.
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)
).
Read,
write, and execute/search permissions on a file are granted to a process
if one or more of the following are true:
- The effective user
- ID
of the
process is super-user.
- 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.
- 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 ID
s 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.
- 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 ID
s
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.
Otherwise, the
corresponding permissions are denied.
A file descriptor is
a small integer used to do I/O
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 simultaneously. A file descriptor is returned by system
calls such as open, or pipe. The file descriptor is used as an argument
by calls such as read, write, ioctl, and close.
Names consisting
of 1 to NAME_MAX
characters may be used to name an ordinary file, special
file or directory.
These characters may be 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 is longer
than NAME_MAX
and _POSIX_NO_TRUNC
is in effect for the path prefix of
that component (see fpathconf(2)
and limits(4)
), it shall be considered
an error condition in that implementation. Otherwise, the implementation
shall use the first NAME_MAX
bytes of the pathname component.
Each session that has established a connection with a controlling
terminal will distinguish one process group of the session as the foreground
process group of the controlling terminal. This group has certain privileges
when accessing its controlling terminal that are denied to background process
groups.
Maximum number of entries in a struct iovec array.
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 pathconf(2)
with the name
argument _PC_LIMIT
.
The file mode creation mask of the process used
during any create function 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.
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.
In a stream, a linked list of messages awaiting processing
by a module or driver.
A message queue identifier (msqid) is a unique
positive integer created by a msgget system call. Each msqid has a message
queue and a data structure 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 msg_cbytes;
ulong msg_qnum;
ulong msg_qbytes;
pid_t msg_lspid;
pid_t msg_lrpid;
time_t msg_stime;
time_t msg_rtime;
time_t msg_ctime;
Here are descriptions of the fields of the msqid_ds structure:
- msg_perm
- 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 seq; /* slot usage sequence # */
key_t key; /* key */
- *msg_first
- is a pointer to the first message on the queue.
- *msg_last
- is
a pointer to the last message on the queue.
- msg_cbytes
- is the current number
of bytes on the queue.
- msg_qnum
- is the number of messages currently on
the queue.
- msg_qbytes
- is the maximum number of bytes allowed on the queue.
- msg_lspid
- is the process ID
of the last process that performed a msgsnd
operation.
- msg_lrpid
- is the process id of the last process that performed
a msgrcv operation.
- msg_stime
- is the time of the last msgsnd operation.
- msg_rtime
- is the time of the last msgrcv operation
- msg_ctime
- is the time
of the last msgctl operation that changed a member of the above structure.
In the msgop and msgctl system call 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 WRITE by user
00040 READ by group
00020 WRITE by group
00004 READ by others
00002 WRITE by others
Read and write permissions on a msqid are granted to a process if one
or more of the following are true:
- The effective user
- ID
of the process
is super-user.
- 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.
- The effective group
- ID
of the process matches msg_perm.cgid or msg_perm.gid
and the appropriate bit of the ‘group’ portion (060) of msg_perm.mode is set.
- The appropriate bit of the ‘other’ portion (006) of
- msg_perm.mode is set.
Otherwise,
the corresponding permissions are denied.
A module is an entity containing
processing routines for input and output 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.
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 constructing them and for connecting multiplexed
configurations of streams.
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.
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 directory.
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.
Each process in the system is uniquely identified during
its lifetime by a positive integer called a process ID
. A process ID
may
not be reused by the system until the process lifetime, process group lifetime
and session lifetime ends for any process ID
, process group ID
and session
ID
equal to that process ID
. Within a process, there are threads with thread
id’s, called thread_t and LWPID_t. These threads are not visible to the
outside process.
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.
Having appropriate privilege means having
the capability to override system restrictions.
Each process
in the system is a member of a process group that is identified 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.
A process group leader is a process whose process
ID
is the same as its 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 (see kill(2)
).
A process lifetime begins when the process is forked and
ends after it exits, when its termination has been acknowledged by its
parent process. See wait(2)
.
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.
In a stream, the message
queue in a module or driver containing messages moving upstream.
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 responsible for the creation of the process.
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 directory of the root file system.
The saved user ID
and saved group ID
are the values of
the effective user ID
and effective group ID
prior to an exec of a file
whose set user or set group file mode bit has been set (see exec(2)
).
A semaphore identifier (semid) is a unique positive
integer created by a semget system call. Each semid has a set of semaphores
and a data structure 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 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 */
Here are descriptions of the fields of the semid_ds structure:
- sem_perm
- is an ipc_perm structure that specifies the semaphore 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 seq; /* slot usage sequence number */
key_t key; /* key */
- sem_nsems
- 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.
- sem_otime
- is the time of the last semop operation.
- sem_ctime
- is the
time of the last semctl operation that changed a member of the above structure.
A semaphore is a data structure called sem that contains the following
members:
ushort semval; /* semaphore value */
pid_t sempid; /* pid of last operation */
ushort semncnt; /* # awaiting semval > cval */
ushort semzcnt; /* # awaiting semval = 0 */
- semval
- is a non-negative integer that is the actual value of the semaphore.
- sempid
- is equal to the process ID
of the last process that performed a
semaphore operation on this semaphore.
- semncnt
- is a count of the number
of processes that are currently suspended awaiting this semaphore’s semval
to become greater than its current value.
- semzcnt
- is a count of the number of processes that are currently suspended
awaiting this semaphore’s semval to become 0.
In the semop and semctl system call 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 on a semid are granted to a process if one or
more of the following are true:
- The effective user
- ID
of the process is
super-user.
- 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.
- The effective group
- ID
of the process matches sem_perm.cgid or sem_perm.gid and the appropriate
bit of the ‘group’ portion (060) of sem_perm.mode is set.
- The appropriate bit
of the ‘other’ portion (06) of
- sem_perm.mode is set.
Otherwise, the corresponding
permissions are denied.
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 session
and process group leader of the process group. A newly created process
joins the session of its creator.
Each session in the system is
uniquely identified during its lifetime by a positive integer called a
session ID
, the process ID
of its session leader.
A session
leader is a process whose session ID
is the same as its process and process
group ID
.
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.
A shared memory identifier (shmid) is a unique
positive integer created by a shmget system call. Each shmid has a segment
of memory (referred to as a shared memory segment) and a data structure
associated with it. (Note that these shared memory segments must be explicitly
removed by the user after the last reference to them is removed.) The data
structure is referred to as shmid_ds and contains the following members:
struct ipc_perm shm_perm; /* operation permission struct */
int shm_segsz; /* size of segment */
struct region *shm_reg; /* ptr to region structure */
char pad[4]; /* for swap compatibility */
pid_t shm_lpid; /* pid of last operation */
pid_t shm_cpid; /* creator pid */
ushort shm_nattch; /* number of current attaches */
ushort 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 */
Here are descriptions of the fields of the shmid_ds structure:
- shm_perm
- 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 seq; /* slot usage sequence # */
key_t key; /* key */
- shm_segsz
- specifies the size of the shared memory segment in bytes.
- shm_cpid
- is the process ID
of the process that created the shared memory identifier.
- shm_lpid
- is the process ID
of the last process that performed a shmop
operation.
- shm_nattch
- is the number of processes that currently have this
segment attached.
- shm_atime
- is the time of the last shmat operation (see
shmop(2)
).
- shm_dtime
- is the time of the last shmdt operation (see shmop(2)
).
- shm_ctime
- is the time of the last shmctl operation that changed one of
the members of the above structure.
In the shmop and shmctl system call
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 WRITE by user
00040 READ by group
00020 WRITE by group
00004 READ by others
00002 WRITE by others
Read and write permissions on a shmid are granted to a process if one
or more of the following are true:
- The effective user
- ID
of the process
is super-user.
- 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.
- The effective group
- ID
of
the process matches shm_perm.cgid or shm_perm.gid and the appropriate bit
of the ‘group’ portion (060) of shm_perm.mode is set.
- The appropriate bit of
the ‘other’ portion (06) of
- shm_perm.mode is set.
Otherwise, the corresponding
permissions are denied.
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.
A set of kernel mechanisms that support the development of network
services and data communication drivers. It defines interface standards
for character input/output 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.
A stream is a full-duplex data path within the kernel between a
user process and driver routines. The primary components 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.
In a stream, the stream head is the end of the stream that
provides the interface between the stream and a user process. The principle
functions of the stream head are processing STREAMS
-related system calls,
and passing data and information between a user process and the stream.
A process is recognized as a super-user process and is granted
special privileges, such as immunity from file permissions, if its effective
user ID
is 0.
In a stream, the direction from driver to stream head.
In a stream, the message queue in a module or driver containing
messages moving downstream.
- Name
- Description
- access(2)
- determine accessibility
of a file
- acct(2)
- enable or disable process accounting
- acl(2)
- get or set
a file’s Access Control List (ACL)
- adjtime(2)
- correct the time to allow
synchronization of the system clock
- alarm(2)
- set a process alarm clock
- audit(2)
- write a record to the audit log
- auditon(2)
- manipulate auditing
- auditsvc(2)
- write audit log to specified file descriptor
- brk(2)
- change
the amount of space allocated for the calling process’s data segment
- chdir(2)
- change working directory
- chmod(2)
- change access permission mode of file
- chown(2)
- change owner and group of a file
- chroot(2)
- change root directory
- close(2)
- close a file descriptor
- creat(2)
- create a new file or rewrite
an existing one
- door(2)
- Solaris 2.5 internal implementation detail
- door_call(2)
- See door(2)
- door_create(2)
- See door(2)
- door_info(2)
- See door(2)
- door_return(2)
- See door(2)
- door_revoke(2)
- See door(2)
- dup(2)
- duplicate an open file descriptor
- exec(2)
- execute a file
- execl(2)
- See exec(2)
- execle(2)
- See exec(2)
- execlp(2)
- See exec(2)
- execv(2)
- See exec(2)
- execve(2)
- See exec(2)
- execvp(2)
- See exec(2)
- _exit(2)
- See exit(2)
- exit(2)
- terminate process
- facl(2)
- See acl(2)
- fchdir(2)
- See chdir(2)
- fchmod(2)
- See chmod(2)
- fchown(2)
- See chown(2)
- fchroot(2)
- See
chroot(2)
- fcntl(2)
- file control
- fork(2)
- create a new process
- fork1(2)
- See
fork(2)
- fpathconf(2)
- get configurable pathname variables
- fstat(2)
- See stat(2)
- fstatvfs(2)
- See statvfs(2)
- getaudit(2)
- get and set process audit information
- getauid(2)
- get and set user audit identity
- getcontext(2)
- get and set current
user context
- getdents(2)
- read directory entries and put in a file system
independent format
- getegid(2)
- See getuid(2)
- geteuid(2)
- See getuid(2)
- getgid(2)
- See getuid(2)
- getgroups(2)
- get or set supplementary group access list IDs
- getitimer(2)
- get or set value of interval timer
- getmsg(2)
- get next message
off a stream
- getpgid(2)
- See getpid(2)
- getpgrp(2)
- See getpid(2)
- getpid(2)
- get process, process group, and parent process IDs
- getpmsg(2)
- See getmsg(2)
- getppid(2)
- See getpid(2)
- getrlimit(2)
- control maximum system resource consumption
- getsid(2)
- get or set session ID
- getuid(2)
- get real user, effective user,
real group, and effective group IDs
- ioctl(2)
- control device
- kill(2)
- send
a signal to a process or a group of processes
- lchown(2)
- See chown(2)
- link(2)
- link to a file
- llseek(2)
- move extended read/write file pointer
- lseek(2)
- move read/write file pointer
- lstat(2)
- See stat(2)
- _lwp_cond_broadcast(2)
- See _lwp_cond_signal(2)
- _lwp_cond_signal(2)
- signal a condition variable
- _lwp_cond_timedwait(2)
- See _lwp_cond_wait(2)
- _lwp_cond_wait(2)
- wait on
a condition variable
- _lwp_continue(2)
- See _lwp_suspend(2)
- _lwp_create(2)
- create a new light-weight process
- _lwp_exit(2)
- terminate the calling LWP
- _lwp_getprivate(2)
- See _lwp_setprivate(2)
- _lwp_info(2)
- return the time-accounting
information of a single LWP
- _lwp_kill(2)
- send a signal to a LWP
- _lwp_makecontext(2)
- initialize an LWP context
- _lwp_mutex_lock(2)
- mutual exclusion
- _lwp_mutex_trylock(2)
- See _lwp_mutex_lock(2)
- _lwp_mutex_unlock(2)
- See _lwp_mutex_lock(2)
- _lwp_self(2)
- get LWP identifier
- _lwp_sema_init(2)
- See _lwp_sema_wait(2)
- _lwp_sema_post(2)
- See _lwp_sema_wait(2)
- _lwp_sema_wait(2)
- semaphore operations
- _lwp_setprivate(2)
- set/get LWP specific storage
- _lwp_sigredirect(2)
- See _signotifywait(2)
- _lwp_suspend(2)
- continue or suspend LWP execution
- _lwp_wait(2)
- wait for
a LWP to terminate
- memcntl(2)
- memory management control
- mincore(2)
- determine
residency of memory pages
- mkdir(2)
- make a directory
- mknod(2)
- make a directory,
or a special or ordinary file
- mmap(2)
- map pages of memory
- mount(2)
- mount
a file system
- mprotect(2)
- set protection of memory mapping
- msgctl(2)
- message
control operations
- msgget(2)
- get message queue
- msgop(2)
- message operations
- msgrcv(2)
- See msgop(2)
- msgsnd(2)
- See msgop(2)
- munmap(2)
- unmap pages of
memory
- nice(2)
- change priority of a process
- open(2)
- open for reading or
writing
- pathconf(2)
- See fpathconf(2)
- pause(2)
- suspend process until signal
- pipe(2)
- create an interprocess channel
- poll(2)
- input/output multiplexing
- p_online(2)
- change processor online or offline status
- pread(2)
- See read(2)
- priocntl(2)
- process scheduler control
- priocntlset(2)
- generalized process
scheduler control
- processor_bind(2)
- bind LWPs to a processor
- processor_info(2)
- determine type and status of a processor
- profil(2)
- execution time profile
- ptrace(2)
- allows a parent process to control the execution of a child process
- putmsg(2)
- send a message on a stream
- putpmsg(2)
- See putmsg(2)
- pwrite(2)
- See write(2)
- read(2)
- read from file
- readlink(2)
- read the value of a symbolic
link
- readv(2)
- See read(2)
- rename(2)
- change the name of a file
- rmdir(2)
- remove a directory
- sbrk(2)
- See brk(2)
- semctl(2)
- semaphore control operations
- semget(2)
- get set of semaphores
- semop(2)
- semaphore operations
- setaudit(2)
- See getaudit(2)
- setauid(2)
- See getauid(2)
- setcontext(2)
- See getcontext(2)
- setegid(2)
- See setuid(2)
- seteuid(2)
- See setuid(2)
- setgid(2)
- See setuid(2)
- setgroups(2)
- See getgroups(2)
- setitimer(2)
- See getitimer(2)
- setpgid(2)
- set process group ID
- setpgrp(2)
- set process group ID
- setregid(2)
- set real
and effective group IDs
- setreuid(2)
- set real and effective user IDs
- setrlimit(2)
- See getrlimit(2)
- setsid(2)
- See getsid(2)
- setuid(2)
- set user and group IDs
- shmat(2)
- See shmop(2)
- shmctl(2)
- shared memory control operations
- shmdt(2)
- See shmop(2)
- shmget(2)
- get shared memory segment identifier
- shmop(2)
- shared
memory operations
- sigaction(2)
- detailed signal management
- sigaltstack(2)
- set or get signal alternate stack context
- _signotifywait(2)
- deliver process
signals to specific LWPs
- sigpending(2)
- examine signals that are blocked
and pending
- sigprocmask(2)
- change and/or examine caller’s signal mask
- sigsend(2)
- send a signal to a process or a group of processes
- sigsendset(2)
- See sigsend(2)
- sigsuspend(2)
- install a signal mask and suspend caller until signal
- sigwait(2)
- wait until a signal is posted
- stat(2)
- get file status
- statvfs(2)
- get file
system information
- stime(2)
- set system time and date
- swapctl(2)
- manage
swap space
- symlink(2)
- make a symbolic link to a file
- sync(2)
- update super
block
- sysfs(2)
- get file system type information
- sysinfo(2)
- get and set
system information strings
- time(2)
- get time
- times(2)
- get process and child
process times
- uadmin(2)
- administrative control
- ulimit(2)
- get and set process
limits
- umask(2)
- set and get file creation mask
- umount(2)
- unmount a file
system
- uname(2)
- get name of current operating system
- unlink(2)
- remove directory
entry
- ustat(2)
- get file system statistics
- utime(2)
- set file access and
modification times
- utimes(2)
- set file times
- vfork(2)
- spawn new process
in a virtual memory efficient way
- vhangup(2)
- virtually ‘hangup’ the current
controlling terminal
- wait(2)
- wait for child process to stop or terminate
- waitid(2)
- wait for child process to change state
- waitpid(2)
- wait for child
process to change state
- write(2)
- write on a file
- writev(2)
- See write(2)
- yield(2)
- yield execution to another lightweight process
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