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msgctl(2) [hpux man page]

msgctl(2)							System Calls Manual							 msgctl(2)

NAME
msgctl() - message control operations SYNOPSIS
DESCRIPTION
provides a variety of message control operations as specified by cmd. The following cmds are available: Place the current value of each member of the data structure associated with msqid into the structure pointed to by buf. The contents of this structure are defined in glossary(9). This command requres the privilege to operate on a message queue not permitted by access modes. This command requires the privi- lege to operate on a message queue in a different compartment. Set the value of the following members of the data structure associated with msqid to the corresponding value found in the structure pointed to by buf: This cmd can only be executed by a process that has the privilege or has an effective user ID equal to the value of either or in the data structure associated with msqid. Only a user with the privilege can raise the value of WARNING: Programs compiled on HP-UX revisions prior to HP-UX 11i v1 use old 16-bit msqid_ds structure fields (obtained via which can describe queue sizes only up to 64 KBytes. Care must be taken such that queues shared with such programs are not made larger than 64 KBytes(65535). Or, those existing programs should be recompiled. Or, the system administrator should restrict the kernel tunable parameter to 64 KBytes or less. Remove the message queue identifier specified by msqid from the system and destroy the message queue and data structure associated with it. This cmd can only be exe- cuted by a process that has the privilege or has an effective user ID equal to the value of either or in the data structure associated with msqid. Security Restrictions Some or all of the actions associated with this system call are subject to compartmental restrictions. See compartments(5) for more infor- mation about compartmentalization on systems that support that feature. Compartmental restrictions can be overridden if the process possesses the privilege (PRIV_COMMALLOWED). Processes owned by the superuser may not have this privilege. Processes owned by any user may have this privilege, depending on system configuration. Some or all of the actions associated with this system call require the or privileges (PRIV_DACREAD, PRIV_LIMIT or PRIV_OWNER). Processes owned by the superuser have these privileges. Processes owned by other users may have one or more of these privileges, depending on system configuration. See privileges(5) for more information about privileged access on systems that support fine-grained privileges. RETURN VALUE
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and is set to indicate the error. ERRORS
fails if one or more of the following is true: msqid is not a valid message queue identifier. cmd is not a valid command, or the command contains invalid parameters. cmd is equal to and Read operation permission is denied to the calling process (see message operation permissions in glos- sary(9)). cmd is equal to or and the calling process does not have the privilege or the effective user ID of the calling process is not equal to the value of either or in the data structure associated with msqid. cmd is equal to an attempt is being made to increase to the value of and the user does not have the privilege. buf points to an illegal address. Reliable detection of this error is implementation dependent. SEE ALSO
ipcrm(1), ipcs(1), msgget(2), msgop(2), ftok(3C), privileges(5). STANDARDS CONFORMANCE
msgctl(2)

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shmctl(2)							System Calls Manual							 shmctl(2)

NAME
shmctl() - shared memory control operations SYNOPSIS
DESCRIPTION
The system call provides a variety of shared memory control operations as specified by the cmd argument. cmd can have the following val- ues: Place the current value of each member of the data structure associated with shmid into the structure pointed to by buf. The contents of this structure are defined in glossary(9). Set the value of the following members of the data structure associated with shmid to the corresponding value found in the structure pointed to by buf: shm_perm.uid shm_perm.gid shm_perm.mode /* only low 9 bits */ This cmd can only be executed by a process that has an effective user ID equal to either that of a user having appro- priate privileges or to the value of either or in the data structure associated with shmid. This cmd cannot be executed on a shared memory segment that has been created with relaxed isolation. Remove the shared memory identifier specified by shmid from the system and destroy the shared memory segment and data structure associated with it. If the segment is attached to one or more processes, then the segment key is changed to and the segment is marked removed. The segment disappears when the last attached process detaches it. This cmd can only be executed by a process that has an effec- tive user ID equal to either that of a user with appropriate privileges or to the value of either or in the data structure associated with shmid. Lock the shared memory segment specified by shmid in memory. This cmd can only be executed by a process that either has an effective user ID equal to that of a user having appropriate privileges or has an effective user ID equal to the value of either or in the data structure associated with shmid and has the privilege (see getprivgrp(2)). Unlock the shared memory segment specified by shmid. This cmd can only be executed by a process that either has an effective user ID equal to a user having appro- priate privileges or has an effective user ID equal to the value of either or in the data structure associated with shmid and has the privilege (see getprivgrp(2)). RETURN VALUE
returns the following values: Successful completion. Failure. is set to indicate the error. ERRORS
If fails, is set to one of the following values. cmd is equal to and Read operation permission is denied to the calling process (see in glossary(9)). buf points to an illegal address. The reliable detection of this error is implementation dependent. cmd is equal to and the shared-memory segment specified by shmid is not locked in memory. shmid is not a valid shared memory identifier. cmd is not a valid command, or the command contains invalid parameters. cmd is equal to and there is not sufficient lockable memory to fill the request. cmd is equal to The attached process count of a shared memory object is too large for the field in the data structure provided by the application. Recompile the application with the latest file to resolve this issue. cmd is equal to or and the effective user ID of the calling process is not equal to that of a user having appropriate privileges and it is not equal to the value of either or in the data structure associated with shmid. cmd is equal to and the shared memory segment has cmd is equal to or and the effective user ID of the calling process is not equal to that of a user having appropriate privileges and the calling process does not have the privilege (see getprivgrp(2)). EXAMPLES
The following call to locks in memory the shared memory segment represented by This example assumes the process has a valid shmid, which can be obtained by calling shmget(2). The following call to removes the shared memory segment represented by This example assumes the process has a valid shmid, which can be obtained by calling (see shmget(2). AUTHOR
was developed by AT&T and HP. SEE ALSO
ipcrm(1), ipcs(1), shmget(2), shmop(2), stdipc(3C), privileges(5), STANDARDS CONFORMANCE
shmctl(2)

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