(ipc.info.gz) shmctl

 
 1.7.4 shmctl
 ------------
 
 Destroys allocated segments. Reads/Writes the control structures.
 
      int shmctl (int shmid, int cmd, struct shmid_ds *buf);
 
    * shmid : id got from call to shmget.
 
    * cmd : IPC_STAT, IPC_SET, IPC_RMID ( syscalls).
           IPC_SET : Used to set the owner uid, gid, and shm_perms.mode
           field.
 
           IPC_RMID : The segment is marked destroyed. It is only
           destroyed on the last detach.
 
           IPC_STAT : The shmid_ds structure is copied into the user
           allocated buffer.
 
    * buf : used to read (IPC_STAT) or write (IPC_SET) information.
 
    * returns : 0 on success, -1 on failure.
 
    The user must execute an IPC_RMID shmctl call to free the memory
 allocated by the shared segment. Otherwise all the pages faulted in
 will continue to live in memory or swap.
 
 Errors:
 EACCES : Do not have permission for requested access.
 EFAULT : buf is not accessible.
 EINVAL : shmid < 0 or unused.
 EIDRM  : identifier destroyed.
 EPERM  : not creator, owner or super-user (IPC_SET, IPC_RMID).

Info Catalog

(ipc.info.gz) shmdt

(ipc.info.gz) Shared Memory

(ipc.info.gz) shmlimits

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