accept(3) accept(3) bind(3) bind(3) accept − accept a connection on a socket

accept(3) accept(3) bind(3) bind(3) accept − accept a connection on a socket
accept(3)
accept(3)
NAME
bind(3)
bind(3)
NAME
accept − accept a connection on a socket
bind − bind a name to a socket
SYNOPSIS
SYNOPSIS
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/socket.h>
int accept(int s, struct sockaddr *addr, int *addrlen);
int bind(int s, const struct sockaddr *name, int namelen);
DESCRIPTION
DESCRIPTION
The argument s is a socket that has been created with socket(3N) and bound to an address with bind(3N),
and that is listening for connections after a call to listen(3N). The accept( ) function extracts the first connection on the queue of pending connections, creates a new socket with the properties of s, and allocates a
new file descriptor, ns, for the socket. If no pending connections are present on the queue and the socket is
not marked as non-blocking, accept( ) blocks the caller until a connection is present. If the socket is
marked as non-blocking and no pending connections are present on the queue, accept( ) returns an error as
described below. The accept( ) function uses the netconfig(4) file to determine the STREAMS device file
name associated with s. This is the device on which the connect indication will be accepted. The accepted
socket, ns, is used to read and write data to and from the socket that connected to ns; it is not used to accept
more connections. The original socket (s) remains open for accepting further connections.
bind( ) assigns a name to an unnamed socket. When a socket is created with socket(3N), it exists in a name
space (address family) but has no name assigned. bind( ) requests that the name pointed to by name be
assigned to the socket.
RETURN VALUES
If the bind is successful, 0 is returned. A return value of −1 indicates an error, which is further specified in
the global errno.
ERRORS
The bind( ) call will fail if:
EACCES
The argument addr is a result parameter that is filled in with the address of the connecting entity as it is
known to the communications layer. The exact format of the addr parameter is determined by the domain
in which the communication occurs.
The requested address is protected and the current user has inadequate permission
to access it.
EADDRINUSE
The specified address is already in use.
EADDRNOTAVAIL
The specified address is not available on the local machine.
The argument addrlen is a value-result parameter. Initially, it contains the amount of space pointed to by
addr; on return it contains the length in bytes of the address returned.
EBADF
s is not a valid descriptor.
The accept( ) function is used with connection-based socket types, currently with SOCK_STREAM.
EINVAL
namelen is not the size of a valid address for the specified address family.
It is possible to select(3C) or poll(2) a socket for the purpose of an accept( ) by selecting or polling it for a
read. However, this will only indicate when a connect indication is pending; it is still necessary to call
accept( ).
EINVAL
The socket is already bound to an address.
ENOSR
There were insufficient STREAMS resources for the operation to complete.
ENOTSOCK
s is a descriptor for a file, not a socket.
RETURN VALUES
The following errors are specific to binding names in the UNIX domain:
The accept( ) function returns −1 on error. If it succeeds, it returns a non-negative integer that is a descriptor for the accepted socket.
EACCES
Search permission is denied for a component of the path prefix of the pathname in
name.
ERRORS
EIO
An I/O error occurred while making the directory entry or allocating the inode.
EBADF
The descriptor is invalid.
EISDIR
A null pathname was specified.
EINTR
The accept attempt was interrupted by the delivery of a signal.
ELOOP
Too many symbolic links were encountered in translating the pathname in name.
EMFILE
The per-process descriptor table is full.
ENOENT
A component of the path prefix of the pathname in name does not exist.
ENODEV
The protocol family and type corresponding to s could not be found in the netconfig file.
ENOTDIR
A component of the path prefix of the pathname in name is not a directory.
EROFS
The inode would reside on a read-only file system.
accept( ) will fail if:
ENOMEM
There was insufficient user memory available to complete the operation.
SEE ALSO
EPROTO
A protocol error has occurred; for example, the STREAMS protocol stack has not
been initialized or the connection has already been released.
NOTES
EWOULDBLOCK
The socket is marked as non-blocking and no connections are present to be
accepted.
unlink(2), socket(3N), attributes(5), socket(5)
Binding a name in the UNIX domain creates a socket in the file system that must be deleted by the caller
when it is no longer needed (using unlink(2)).
The rules used in name binding vary between communication domains.
SEE ALSO
poll(2), bind(3N), connect(3N), listen(3N), select(3C), socket(3N), netconfig(4), attributes(5), socket(5)
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fdopen(3)
fdopen(3)
NAME
ip(7)
ip(7)
NAME
fdopen − associate a stream with a file descriptor
ip − Linux IPv4 protocol implementation
SYNOPSIS
SYNOPSIS
#include <stdio.h>
#include <sys/socket.h>
#include <netinet/in.h>
FILE *fdopen(int fildes, const char *mode);
DESCRIPTION
tcp_socket = socket(PF_INET, SOCK_STREAM, 0);
raw_socket = socket(PF_INET, SOCK_RAW, protocol);
udp_socket = socket(PF_INET, SOCK_DGRAM, protocol);
The fdopen( ) function associates a stream with a file descriptor fildes, whose value must be less than 255.
The mode argument is a character string having one of the following values:
r or rb
w or wb
a or ab
r+ or rb+ or r+b
w+ or wb+ or w+b
a+ or ab+ or a+b
DESCRIPTION
open a file for reading
open a file for writing
open a file for writing at end of file
open a file for update (reading and writing)
open a file for update (reading and writing)
open a file for update (reading and writing) at end of file
The programmer’s interface is BSD sockets compatible. For more information on sockets, see socket(7).
The meaning of these flags is exactly as specified in fopen(3S), except that modes beginning with w do not
cause truncation of the file.
The mode of the stream must be allowed by the file access mode of the open file. The file position indicator
associated with the new stream is set to the position indicated by the file offset associated with the file
descriptor.
fdopen( ) will preserve the offset maximum previously set for the open file description corresponding to
fildes.
The error and end-of-file indicators for the stream are cleared. The fdopen( ) function may cause the
st_atime field of the underlying file to be marked for update.
An IP socket is created by calling the socket(2) function as socket(PF_INET, socket_type, protocol).
Valid socket types are SOCK_STREAM to open a tcp(7) socket, SOCK_DGRAM to open a udp(7)
socket, or SOCK_RAW to open a raw(7) socket to access the IP protocol directly. protocol is the IP protocol in the IP header to be received or sent. The only valid values for protocol are 0 and IPPROTO_TCP
for TCP sockets and 0 and IPPROTO_UDP for UDP sockets.
When a process wants to receive new incoming packets or connections, it should bind a socket to a local
interface address using bind(2). Only one IP socket may be bound to any given local (address, port) pair.
When INADDR_ANY is specified in the bind call the socket will be bound to all local interfaces. When
listen(2) or connect(2) are called on a unbound socket the socket is automatically bound to a random free
port with the local address set to INADDR_ANY.
ADDRESS FORMAT
An IP socket address is defined as a combination of an IP interface address and a port number. The basic IP
protocol does not supply port numbers, they are implemented by higher level protocols like tcp(7).
RETURN VALUES
struct sockaddr_in {
sa_family_t
sin_family;
u_int16_t
sin_port;
struct in_addr sin_addr;
};
/* Internet address. */
struct in_addr {
u_int32_t
s_addr;
};
Upon successful completion, fdopen( ) returns a pointer to a stream. Otherwise, a null pointer is returned
and errno is set to indicate the error.
fdopen( ) may fail and not set errno if there are no free stdio streams.
ERRORS
The fdopen( ) function may fail if:
EBADF
The fildes argument is not a valid file descriptor.
EINVAL
The mode argument is not a valid mode.
EMFILE
FOPEN_MAX streams are currently open in the calling process.
EMFILE
STREAM_MAX streams are currently open in the calling process.
/* address family: AF_INET */
/* port in network byte order */
/* internet address */
/* address in network byte order */
sin_family is always set to AF_INET. This is required; in Linux 2.2 most networking functions return
EINVAL when this setting is missing. sin_port contains the port in network byte order. The port numbers
below 1024 are called reserved ports. Only processes with effective user id 0 or the
CAP_NET_BIND_SERVICE capability may bind(2) to these sockets.
ENOMEM Insufficient space to allocate a buffer.
USAGE
STREAM_MAX is the number of streams that one process can have open at one time. If defined, it has the
same value as FOPEN_MAX.
File descriptors are obtained from calls like open(2), dup(2), creat(2) or pipe(2), which open files but do
not return streams. Streams are necessary input for almost all of the Section 3S library routines.
SEE ALSO
sin_addr is the IP host address. The addr member of struct in_addr contains the host interface address in
network order. in_addr should be only accessed using the inet_aton(3), inet_addr(3), inet_makeaddr(3)
library functions or directly with the name resolver (see gethostbyname(3)).
Note that the address and the port are always stored in network order. In particular, this means that you
need to call htons(3) on the number that is assigned to a port. All address/port manipulation functions in
the standard library work in network order.
creat(2), dup(2), open(2), pipe(2), fclose(3S), fopen(3S), attributes(5)
SEE ALSO
sendmsg(2), recvmsg(2), socket(7), netlink(7), tcp(7), udp(7), raw(7), ipfw(7)
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sigaction(2)
sigaction(2)
NAME
sigsetops(3C)
sigsetops(3C)
NAME
sigaction − POSIX signal handling functions.
sigsetops, sigemptyset, sigfillset, sigaddset, sigdelset, sigismember − manipulate sets of signals
SYNOPSIS
SYNOPSIS
#include <signal.h>
#include <signal.h>
int sigemptyset(sigset_t *set);
int sigaction(int signum, const struct sigaction *act, struct sigaction *oldact);
int sigfillset(sigset_t *set);
DESCRIPTION
The sigaction system call is used to change the action taken by a process on receipt of a specific signal.
int sigaddset(sigset_t *set, int signo);
signum specifies the signal and can be any valid signal except SIGKILL and SIGSTOP.
int sigdelset(sigset_t *set, int signo);
If act is non−null, the new action for signal signum is installed from act. If oldact is non−null, the previous
action is saved in oldact.
int sigismember(sigset_t *set, int signo);
DESCRIPTION
These functions manipulate sigset_t data types, representing the set of signals supported by the implementation.
The sigaction structure is defined as something like
struct sigaction {
void (*sa_handler)(int);
void (*sa_sigaction)(int, siginfo_t *, void *);
sigset_t sa_mask;
int sa_flags;
void (*sa_restorer)(void);
}
sigemptyset( ) initializes the set pointed to by set to exclude all signals defined by the system.
sigfillset( ) initializes the set pointed to by set to include all signals defined by the system.
sigaddset( ) adds the individual signal specified by the value of signo to the set pointed to by set.
sigdelset( ) deletes the individual signal specified by the value of signo from the set pointed to by set.
sigismember( ) checks whether the signal specified by the value of signo is a member of the set pointed to
by set.
On some architectures a union is involved - do not assign to both sa_handler and sa_sigaction.
The sa_restorer element is obsolete and should not be used. POSIX does not specify a sa_restorer element.
sa_handler specifies the action to be associated with signum and may be SIG_DFL for the default action,
SIG_IGN to ignore this signal, or a pointer to a signal handling function.
sa_mask gives a mask of signals which should be blocked during execution of the signal handler. In addition, the signal which triggered the handler will be blocked, unless the SA_NODEFER or SA_NOMASK
flags are used.
sa_flags specifies a set of flags which modify the behaviour of the signal handling process. It is formed by
the bitwise OR of zero or more of the following:
SA_NOCLDSTOP
If signum is SIGCHLD, do not receive notification when child processes stop (i.e., when
child processes receive one of SIGSTOP, SIGTSTP, SIGTTIN or SIGTTOU).
SA_RESTART
Provide behaviour compatible with BSD signal semantics by making certain system calls
restartable across signals.
Any object of type sigset_t must be initialized by applying either sigemptyset( ) or sigfillset( ) before
applying any other operation.
RETURN VALUES
Upon successful completion, the sigismember( ) function returns a value of one if the specified signal is a
member of the specified set, or a value of 0 if it is not. Upon successful completion, the other functions
return a value of 0. Otherwise a value of −1 is returned and errno is set to indicate the error.
ERRORS
sigaddset( ), sigdelset( ), and sigismember( ) will fail if the following is true:
EINVAL
The value of the signo argument is not a valid signal number.
sigfillset( ) will fail if the following is true:
EFAULT
The set argument specifies an invalid address.
SEE ALSO
sigaction(2), sigpending(2), sigprocmask(2), sigsuspend(2), attributes(5), signal(5)
RETURN VALUES
sigaction returns 0 on success and -1 on error.
ERRORS
EINVAL
An invalid signal was specified. This will also be generated if an attempt is made to change the
action for SIGKILL or SIGSTOP, which cannot be caught.
SEE ALSO
kill(1), kill(2), killpg(2), pause(2), sigsetops(3),
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socket(3)
socket(3)
socket − create an endpoint for communication
SYNOPSIS
cc [ flag . . . ] file . . . −lsocket −lnsl [ library . . . ]
SOCK_SEQPACKET sockets employ the same system calls as SOCK_STREAM sockets. The only difference is that read(2) calls will return only the amount of data requested, and any remaining in the arriving
packet will be discarded.
#include <sys/types.h>
#include <sys/socket.h>
SOCK_DGRAM and SOCK_RAW sockets allow datagrams to be sent to correspondents named in
sendto(3N) calls. Datagrams are generally received with recvfrom(3N), which returns the next datagram
with its return address.
int socket(int domain, int type, int protocol);
DESCRIPTION
socket( ) creates an endpoint for communication and returns a descriptor.
The domain parameter specifies a communications domain within which communication will take place;
this selects the protocol family which should be used. The protocol family generally is the same as the
address family for the addresses supplied in later operations on the socket. These families are defined in
the include file <sys/socket.h>. There must be an entry in the netconfig(4) file for at least each protocol
family and type required. If protocol has been specified, but no exact match for the tuplet family, type, protocol is found, then the first entry containing the specified family and type with zero for protocol will be
used. The currently understood formats are:
UNIX system internal protocols
PF_INET
ARPA Internet protocols
socket(3)
activity. An error is then indicated if no response can be elicited on an otherwise idle connection for a
extended period (for instance 5 minutes). A SIGPIPE signal is raised if a process sends on a broken stream;
this causes naive processes, which do not handle the signal, to exit.
NAME
PF_UNIX
socket(3)
An fcntl(2) call can be used to specify a process group to receive a SIGURG signal when the out-of-band
data arrives. It may also enable non-blocking I/O and asynchronous notification of I/O events with SIGIO
signals.
The operation of sockets is controlled by socket level options. These options are defined in the file
<sys/socket.h>. setsockopt(3N) and getsockopt(3N) are used to set and get options, respectively.
RETURN VALUES
A −1 is returned if an error occurs. Otherwise the return value is a descriptor referencing the socket.
ERRORS
The socket( ) call fails if:
The socket has the indicated type, which specifies the communication semantics. Currently defined types
are:
SOCK_STREAM
SOCK_DGRAM
SOCK_RAW
SOCK_SEQPACKET
SOCK_RDM
A SOCK_STREAM type provides sequenced, reliable, two-way connection-based byte streams. An out-ofband data transmission mechanism may be supported. A SOCK_DGRAM socket supports datagrams (connectionless, unreliable messages of a fixed (typically small) maximum length). A SOCK_SEQPACKET
socket may provide a sequenced, reliable, two-way connection-based data transmission path for datagrams
of fixed maximum length; a consumer may be required to read an entire packet with each read system call.
This facility is protocol specific, and presently not implemented for any protocol family. SOCK_RAW
sockets provide access to internal network interfaces. The types SOCK_RAW, which is available only to
the super-user, and SOCK_RDM, for which no implementation currently exists, are not described here.
EACCES
Permission to create a socket of the specified type and/or protocol is denied.
EMFILE
The per-process descriptor table is full.
ENOMEM
Insufficient user memory is available.
ENOSR
There were insufficient STREAMS resources available to complete the operation.
EPROTONOSUPPORT
The protocol type or the specified protocol is not supported within this
domain.
SEE ALSO
close(2), fcntl(2), ioctl(2), read(2), write(2), accept(3N), bind(3N), connect(3N), getsockname(3N), getsockopt(3N), listen(3N), recv(3N), setsockopt(3N), send(3N), shutdown(3N), socketpair(3N),
attributes(5), in(5), socket(5)
protocol specifies a particular protocol to be used with the socket. Normally only a single protocol exists to
support a particular socket type within a given protocol family. However, multiple protocols may exist, in
which case a particular protocol must be specified in this manner. The protocol number to use is particular
to the “communication domain” in which communication is to take place. If a protocol is specified by the
caller, then it will be packaged into a socket level option request and sent to the underlying protocol layers.
Sockets of type SOCK_STREAM are full-duplex byte streams, similar to pipes. A stream socket must be in
a connected state before any data may be sent or received on it. A connection to another socket is created
with a connect(3N) call. Once connected, data may be transferred using read(2) and write(2) calls or
some variant of the send(3N) and recv(3N) calls. When a session has been completed, a close(2) may be
performed. Out-of-band data may also be transmitted as described on the send(3N) manual page and
received as described on the recv(3N) manual page.
The communications protocols used to implement a SOCK_STREAM insure that data is not lost or duplicated. If a piece of data for which the peer protocol has buffer space cannot be successfully transmitted
within a reasonable length of time, then the connection is considered broken and calls will indicate an error
with −1 returns and with ETIMEDOUT as the specific code in the global variable errno. The protocols
optionally keep sockets “warm” by forcing transmissions roughly every minute in the absence of other
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stat(2)
stat(2)
stat(2)
stat(2)
The field st_ctime is changed by writing or by setting inode information (i.e., owner, group, link count,
mode, etc.).
NAME
stat, fstat, lstat − get file status
The following POSIX macros are defined to check the file type:
SYNOPSIS
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
int stat(const char * file_name, struct stat *buf );
int fstat(int filedes, struct stat *buf );
int lstat(const char * file_name, struct stat *buf );
DESCRIPTION
These functions return information about the specified file. You do not need any access rights to the file to
get this information but you need search rights to all directories named in the path leading to the file.
is it a regular file?
directory?
S_ISCHR(m)
character device?
S_ISBLK(m)
block device?
S_ISFIFO(m)
fifo?
S_ISLNK(m)
symbolic link? (Not in POSIX.1-1996.)
S_ISSOCK(m)
socket? (Not in POSIX.1-1996.)
The following flags are defined for the st_mode field:
stat stats the file pointed to by file_name and fills in buf .
lstat is identical to stat, except in the case of a symbolic link, where the link itself is stat-ed, not the file that
it refers to.
fstat is identical to stat, only the open file pointed to by filedes (as returned by open(2)) is stat-ed in place
of file_name.
They all return a stat structure, which contains the following fields:
struct stat {
dev_t
ino_t
mode_t
nlink_t
uid_t
gid_t
dev_t
off_t
blksize_t
blkcnt_t
time_t
time_t
time_t
};
S_ISREG(m)
S_ISDIR(m)
st_dev;
/* device */
st_ino; /* inode */
st_mode; /* protection */
st_nlink; /* number of hard links */
st_uid; /* user ID of owner */
st_gid; /* group ID of owner */
st_rdev; /* device type (if inode device) */
st_size; /* total size, in bytes */
st_blksize; /* blocksize for filesystem I/O */
st_blocks; /* number of blocks allocated */
st_atime; /* time of last access */
st_mtime; /* time of last modification */
st_ctime; /* time of last status change */
S_IFMT
S_IFSOCK
S_IFLNK
S_IFREG
S_IFBLK
S_IFDIR
S_IFCHR
S_IFIFO
S_ISUID
S_ISGID
S_ISVTX
S_IRWXU
S_IRUSR
S_IWUSR
S_IXUSR
S_IRWXG
S_IRGRP
S_IWGRP
S_IXGRP
S_IRWXO
S_IROTH
S_IWOTH
S_IXOTH
0170000
0140000
0120000
0100000
0060000
0040000
0020000
0010000
0004000
0002000
0001000
00700
00400
00200
00100
00070
00040
00020
00010
00007
00004
00002
00001
bitmask for the file type bitfields
socket
symbolic link
regular file
block device
directory
character device
fifo
set UID bit
set GID bit (see below)
sticky bit (see below)
mask for file owner permissions
owner has read permission
owner has write permission
owner has execute permission
mask for group permissions
group has read permission
group has write permission
group has execute permission
mask for permissions for others (not in group)
others have read permission
others have write permisson
others have execute permission
The value st_size gives the size of the file (if it is a regular file or a symlink) in bytes. The size of a symlink
is the length of the pathname it contains, without trailing NUL.
The set GID bit (S_ISGID) has several special uses: For a directory it indicates that BSD semantics is to be
used for that directory: files created there inherit their group ID from the directory, not from the effective
group ID of the creating process, and directories created there will also get the S_ISGID bit set. For a file
that does not have the group execution bit (S_IXGRP) set, it indicates mandatory file/record locking.
The value st_blocks gives the size of the file in 512-byte blocks. (This may be smaller than st_size/512 e.g.
when the file has holes.) The value st_blksize gives the "preferred" blocksize for efficient file system I/O.
(Writing to a file in smaller chunks may cause an inefficient read-modify-rewrite.)
The ‘sticky’ bit (S_ISVTX) on a directory means that a file in that directory can be renamed or deleted only
by the owner of the file, by the owner of the directory, and by a privileged process.
Not all of the Linux filesystems implement all of the time fields. Some file system types allow mounting in
such a way that file accesses do not cause an update of the st_atime field. (See ‘noatime’ in mount(8).)
The field st_atime is changed by file accesses, e.g. by execve(2), mknod(2), pipe(2), utime(2) and read(2)
(of more than zero bytes). Other routines, like mmap(2), may or may not update st_atime.
RETURN VALUE
On success, zero is returned. On error, −1 is returned, and errno is set appropriately.
SEE ALSO
chmod(2), chown(2), readlink(2), utime(2), capabilities(7)
The field st_mtime is changed by file modifications, e.g. by mknod(2), truncate(2), utime(2) and write(2)
(of more than zero bytes). Moreover, st_mtime of a directory is changed by the creation or deletion of files
in that directory. The st_mtime field is not changed for changes in owner, group, hard link count, or mode.
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strerror(3)
strerror(3)
NAME
waitpid(2)
waitpid(2)
NAME
strerror, strerror_r − return string describing error code
waitpid − wait for child process to change state
SYNOPSIS
SYNOPSIS
#include <string.h>
#include <sys/types.h>
#include <sys/wait.h>
char *strerror(int errnum);
int strerror_r(int errnum, char *buf , size_t n);
pid_t waitpid(pid_t pid, int *stat_loc, int options);
DESCRIPTION
DESCRIPTION
The strerror() function returns a string describing the error code passed in the argument errnum, possibly
using the LC_MESSAGES part of the current locale to select the appropriate language. This string must
not be modified by the application, but may be modified by a subsequent call to perror() or strerror(). No
library function will modify this string.
waitpid( ) suspends the calling process until one of its children changes state; if a child process changed
state prior to the call to waitpid( ), return is immediate. pid specifies a set of child processes for which status is requested.
If pid is equal to (pid_t)−1, status is requested for any child process.
If pid is greater than (pid_t)0, it specifies the process ID of the child process for which status is
requested.
The strerror_r() function is similar to strerror(), but is thread safe. It returns the string in the user-supplied buffer buf of length n.
If pid is equal to (pid_t)0 status is requested for any child process whose process group ID is equal
to that of the calling process.
RETURN VALUE
The strerror() function returns the appropriate error description string, or an unknown error message if the
error code is unknown. The value of errno is not changed for a successful call, and is set to a nonzero value
upon error. The strerror_r() function returns 0 on success and −1 on failure, setting errno.
ERRORS
If pid is less than (pid_t)−1, status is requested for any child process whose process group ID is
equal to the absolute value of pid.
If waitpid( ) returns because the status of a child process is available, then that status may be evaluated with
the macros defined by wstat(5). If the calling process had specified a non-zero value of stat_loc, the status
of the child process will be stored in the location pointed to by stat_loc.
EINVAL
The value of errnum is not a valid error number.
The options argument is constructed from the bitwise inclusive OR of zero or more of the following flags,
defined in the header <sys/wait.h>:
ERANGE
Insufficient storage was supplied to contain the error description string.
WCONTINUED
The status of any continued child process specified by pid, whose status has not
been reported since it continued, is also reported to the calling process.
WNOHANG
waitpid( ) will not suspend execution of the calling process if status is not immediately available for one of the child processes specified by pid.
WNOWAIT
Keep the process whose status is returned in stat_loc in a waitable state. The process may be waited for again with identical results.
CONFORMING TO
SVID 3, POSIX, BSD 4.3, ISO/IEC 9899:1990 (C89).
strerror_r() with prototype as given above is specified by SUSv3, and was in use under Digital Unix and
HP Unix. An incompatible function, with prototype
RETURN VALUES
char *strerror_r(int errnum, char *buf , size_t n);
is a GNU extension used by glibc (since 2.0), and must be regarded as obsolete in view of SUSv3. The
GNU version may, but need not, use the user-supplied buffer. If it does, the result may be truncated in case
the supplied buffer is too small. The result is always NUL-terminated.
SEE ALSO
If waitpid( ) returns because the status of a child process is available, this function returns a value equal to
the process ID of the child process for which status is reported. If waitpid( ) returns due to the delivery of a
signal to the calling process, −1 is returned and errno is set to EINTR. If this function was invoked with
WNOHANG set in options, it has at least one child process specified by pid for which status is not available,
and status is not available for any process specified by pid, 0 is returned. Otherwise, −1 is returned, and
errno is set to indicate the error.
ERRORS
errno(3), perror(3), strsignal(3)
waitpid( ) will fail if one or more of the following is true:
ECHILD
The process or process group specified by pid does not exist or is not a child of the calling process or can never be in the states specified by options.
EINTR
waitpid( ) was interrupted due to the receipt of a signal sent by the calling process.
EINVAL
An invalid value was specified for options.
SEE ALSO
exec(2), exit(2), fork(2), sigaction(2), wstat(5)
SPI-Klausur Manual-Auszug
2005-03-07
1
SPI-Klausur Manual-Auszug
2005-03-07
1
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