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1.1 ! root 1: .TH SEMCTL 2 ! 2: .SH NAME ! 3: semctl \- semaphore control operations ! 4: .SH SYNOPSIS ! 5: .B #include <sys/types.h> ! 6: .br ! 7: .B #include <sys/ipc.h> ! 8: .br ! 9: .B #include <sys/sem.h> ! 10: .PP ! 11: .nf ! 12: .B "int semctl (semid, semnum, cmd, arg)" ! 13: .B int semid, cmd; ! 14: .B int semnum; ! 15: .B union semun { ! 16: .RS ! 17: .ta 8n 28n ! 18: .nf ! 19: .B int val; ! 20: .B struct semid_ds \(**buf; ! 21: .B ushort \(**array; ! 22: .fi ! 23: .RE ! 24: .B } arg; ! 25: .tr ~~ ! 26: .SH DESCRIPTION ! 27: .I Semctl ! 28: provides a variety of semaphore control operations as specified by ! 29: .IR cmd . ! 30: .PP ! 31: The following ! 32: .IR cmd s ! 33: are executed with respect to the semaphore specified by ! 34: .IR semid " and " semnum: ! 35: .RS ! 36: .TP \w'\fBIPC_RMID\fP\ \ \ 'u ! 37: .SM ! 38: .B GETVAL ! 39: Return the value of semval (see ! 40: .IR intro (2)). ! 41: .SM {READ} ! 42: .TP \w'\fBIPC_RMID\fP\ \ \ 'u ! 43: .SM ! 44: .B SETVAL ! 45: Set the value of semval to ! 46: .IR arg.val . ! 47: .SM {ALTER} ! 48: When this cmd is successfully executed, the semadj value corresponding to the ! 49: specified semaphore in all processes is cleared. ! 50: .TP \w'\fBIPC_RMID\fP\ \ \ 'u ! 51: .SM ! 52: .B GETPID ! 53: Return the value of sempid. ! 54: .SM {READ} ! 55: .TP \w'\fBIPC_RMID\fP\ \ \ 'u ! 56: .SM ! 57: .B GETNCNT ! 58: Return the value of semncnt. ! 59: .SM {READ} ! 60: .TP \w'\fBIPC_RMID\fP\ \ \ 'u ! 61: .SM ! 62: .B GETZCNT ! 63: Return the value of semzcnt. ! 64: .SM {READ} ! 65: .RE ! 66: .PP ! 67: The following ! 68: .IR cmd s ! 69: return and set, respectively, every semval in the set of semaphores. ! 70: .RS ! 71: .TP \w'\fBIPC_RMID\fP\ \ \ 'u ! 72: .SM ! 73: .B GETALL ! 74: Place semvals into array pointed to by ! 75: .IR arg.array . ! 76: .SM {READ} ! 77: .TP \w'\fBIPC_RMID\fP\ \ \ 'u ! 78: .SM ! 79: .B SETALL ! 80: Set semvals according to the array pointed to by ! 81: .IR arg.array . ! 82: .SM {ALTER} ! 83: When this cmd is successfully executed the semadj values corresponding to each ! 84: specified semaphore in all processes are cleared. ! 85: .RE ! 86: .PP ! 87: The following ! 88: .IR cmd s ! 89: are also available: ! 90: .RS ! 91: .TP \w'\fBIPC_RMID\fP\ \ \ 'u ! 92: .SM ! 93: .B IPC_STAT ! 94: Place the current value of each member of the data structure associated with ! 95: .I semid ! 96: into the structure pointed to by ! 97: .IR arg.buf . ! 98: The contents of this structure are defined in ! 99: .IR intro (2). ! 100: .SM {READ} ! 101: .TP \w'\fBIPC_RMID\fP\ \ \ 'u ! 102: .SM ! 103: .B IPC_SET ! 104: Set the value of the following members of the data structure associated with ! 105: .I semid ! 106: to the corresponding value found in the structure pointed to by ! 107: .IR arg.buf : ! 108: .SP 1v ! 109: .RS ! 110: .nf ! 111: .B sem_perm.uid ! 112: .B sem_perm.gid ! 113: .B "sem_perm.mode /\(** only low 9 bits \(**/" ! 114: .fi ! 115: .RE ! 116: .IP ! 117: This cmd can only be executed by a process that has an effective user ! 118: .SM ID ! 119: equal to either that of super-user or to the value of ! 120: .B sem_perm.uid ! 121: in the data structure associated with ! 122: .IR semid . ! 123: .TP \w'\fBIPC_RMID\fP\ \ \ 'u ! 124: .SM ! 125: .B IPC_RMID ! 126: Remove the semaphore identifier specified by ! 127: .I semid ! 128: from the system and destroy the set of semaphores and data structure ! 129: associated with it. ! 130: This cmd can only be executed by a process that has an effective user ! 131: .SM ID ! 132: equal to either that of super-user or to the value of ! 133: .B sem_perm.uid ! 134: in the data structure associated with ! 135: .IR semid . ! 136: .PP ! 137: .I Semctl ! 138: will fail if one or more of the following are true: ! 139: .TP 15 ! 140: \s-1\%[EINVAL]\s+1 ! 141: .I Semid ! 142: is not a valid semaphore identifier. ! 143: .TP ! 144: \s-1\%[EINVAL]\s+1 ! 145: .I Semnum ! 146: is less than zero or greater than ! 147: .BR sem_nsems . ! 148: .TP ! 149: \s-1\%[EINVAL]\s+1 ! 150: .I Cmd ! 151: is not a valid command. ! 152: .TP ! 153: \s-1\%[EACCES]\s+1 ! 154: Operation permission is denied to the calling process (see ! 155: .IR intro (2)). ! 156: .TP ! 157: \s-1\%[ERANGE]\s+1 ! 158: .I Cmd ! 159: is ! 160: .SM ! 161: .B SETVAL ! 162: or ! 163: .SM ! 164: .B SETALL ! 165: and the value to which semval is to be set is greater than ! 166: the system imposed maximum. ! 167: .TP ! 168: \s-1\%[EPERM]\s+1 ! 169: .I Cmd ! 170: is equal to ! 171: .SM ! 172: .B IPC_RMID ! 173: or ! 174: .SM ! 175: .B IPC_SET ! 176: and the effective user ! 177: .SM ID ! 178: of the calling process is not equal to that of super-user and it is ! 179: not equal to the value of ! 180: .B sem_perm.uid ! 181: in the data structure associated with ! 182: .IR semid . ! 183: .TP ! 184: \s-1\%[EFAULT]\s+1 ! 185: .I Arg.buf ! 186: points to an illegal address. ! 187: .SH "RETURN VALUE" ! 188: Upon successful completion, ! 189: the value returned depends on ! 190: .I cmd\^ ! 191: as follows: ! 192: .PD 0 ! 193: .RS ! 194: .TP 1.5i ! 195: .SM ! 196: .B GETVAL ! 197: The value of semval. ! 198: .TP ! 199: .SM ! 200: .B GETPID ! 201: The value of sempid. ! 202: .TP ! 203: .SM ! 204: .B GETNCNT ! 205: The value of semncnt. ! 206: .TP ! 207: .SM ! 208: .B GETZCNT ! 209: The value of semzcnt. ! 210: .TP ! 211: All others ! 212: A value of 0. ! 213: .RE ! 214: .PP ! 215: .PD ! 216: Otherwise, a value of \-1 is returned and ! 217: .I errno\^ ! 218: is set to indicate the error. ! 219: .SH SEE ALSO ! 220: intro(2), semget(2), semop(2). ! 221: .\" @(#)semctl.2 6.2 of 9/6/83
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