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1 perry 1 SETPGID
2 !!!SETPGID
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 RETURN VALUE
7 ERRORS
8 CONFORMING TO
9 NOTES
10 SEE ALSO
11 ----
12 !!NAME
13
14
15 setpgid, getpgid, setpgrp, getpgrp - set/get process group
16 !!SYNOPSIS
17
18
19 __#include __
20
21
22 __int setpgid(pid_t__ ''pid''__, pid_t__
23 ''pgid''__);
24 pid_t getpgid(pid_t__ ''pid''__);
25 int setpgrp(void);
26 pid_t getpgrp(void);__
27 !!DESCRIPTION
28
29
30 __setpgid__ sets the process group ID of the process
31 specified by ''pid'' to ''pgid''. If ''pid'' is
32 zero, the process ID of the current process is used. If
33 ''pgid'' is zero, the process ID of the process specified
34 by ''pid'' is used. If __setpgid__ is used to move a
35 process from one process group to another (as is done by
36 some shells when creating pipelines), both process groups
37 must be part of the same session. In this case, the
38 ''pgid'' specifies an existing process group to be joined
39 and the session ID of that group must match the session ID
40 of the joining process.
41
42
43 __getpgid__ returns the process group ID of the process
44 specified by ''pid''. If ''pid'' is zero, the process
45 ID of the current process is used.
46
47
48 In the Linux DLL 4.4.1 library, __setpgrp__ simply calls
49 __setpgid(0,0)__.
50
51
52 __getpgrp__ is equivalent to __getpgid(0)__. Each
53 process group is a member of a session and each process is a
54 member of the session of which its process group is a
55 member.
56
57
58 Process groups are used for distribution of signals, and by
59 terminals to arbitrate requests for their input: Processes
60 that have the same process group as the terminal are
61 foreground and may read, while others will block with a
62 signal if they attempt to read. These calls are thus used by
63 programs such as csh(1) to create process groups in
64 implementing job control. The __TIOCGPGRP__ and
65 __TIOCSPGRP__ calls described in termios(4) are
66 used to get/set the process group of the control
67 terminal.
68
69
70 If a session has a controlling terminal, CLOCAL is not set
71 and a hangup occurs, then the session leader is sent a
72 SIGHUP. If the session leader exits, the SIGHUP signal will
73 be sent to each process in the foreground process group of
74 the controlling terminal.
75
76
77 If the exit of the process causes a process group to become
78 orphaned, and if any member of the newly-orphaned process
79 group is stopped, then a SIGHUP signal followed by a SIGCONT
80 signal will be sent to each process in the newly-orphaned
81 process group.
82 !!RETURN VALUE
83
84
85 On success, __setpgid__ and __setpgrp__ return zero.
86 On error, -1 is returned, and ''errno'' is set
87 appropriately.
88
89
90 __getpgid__ returns a process group on success. On error,
91 -1 is returned, and ''errno'' is set
92 appropriately.
93
94
95 __getpgrp__ always returns the current process
96 group.
97 !!ERRORS
98
99
100 __EINVAL__
101
102
103 ''pgid'' is less than 0.
104
105
106 __EPERM__
107
108
109 Various permission violations.
110
111
112 __ESRCH__
113
114
115 ''pid'' does not match any process.
116 !!CONFORMING TO
117
118
119 The functions __setpgid__ and __getpgrp__ conform to
120 POSIX.1. The function __setpgrp__ is from BSD 4.2. The
121 function __getpgid__ conforms to SVr4.
122 !!NOTES
123
124
125 POSIX took __setpgid__ from the BSD function
126 __setpgrp__. Also SysV has a function with the same name,
127 but it is identical to setsid(2).
128 !!SEE ALSO
129
130
131 getuid(2), setsid(2), tcsetpgrp(3),
132 termios(4)
133 ----
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