qer(8) [plan9 man page]

QER(8)							      System Manager's Manual							    QER(8)

NAME

       qer, runq - queues management for spooled files

SYNOPSIS

       qer root tag reply args
       runq [ -ad ] root cmd

DESCRIPTION

       Qer  creates  a	control  and a data file in a queue directory.	The control file contents consist of the tag, reply, and args separated by
       spaces.	The data file contains the standard input to qer.  The files are created in the directory root/user, where user is the contents of
       /dev/user.  Mktemp(2) is used to create the actual names of the control and data file.

       Runq  processes	the files queued by qer.  Without the -a option, runq processes all requests in the directory root/user, where user is the
       contents of /dev/user.  With the -a it processes all requests.  Each request is processed by executing the command cmd with the contents of
       the  control  file  as  its  arguments,	the contents of the data file as its standard input, and standard error appended to the error file
       E.XXXXXX.

       The action taken by runq depends on the return status of cmd.  If cmd returns a null status, the processing is assumed successful  and  the
       control,  data,	and error files are removed.  If cmd returns an error status containing the word the files are left to be reprocessed at a
       later time.  For any other status, an error message is mailed to the requester and the files are removed.  Runq uses the reply field in the
       control file as a mail address to which to send an error notification.  The notification contains the contents of the control file to iden-
       tify the failed request.

       To avoid reprocessing files too often, the following algorithm is used: a data file younger than one hour will  not  be	processed  if  its
       error  file  exists  and  was  last modified within the preceding 10 minutes.  A data file older than one hour will not be processed if its
       error file exists and was last modified within the preceding hour.

       The -d option causes debugging output on standard error describing the progress through the queues.

       Runq is often called from cron(8) by an entry such as

	      0,10,20,30,40,50 * * * * kremvax
		      runq -a /mail/queue /mail/lib/remotemail

       The entry must be a single line; it is folded here only so it fits on the page.

FILES

       root/user
	      queue directory for user

       root/user/D.XXXXXX
	      data file

       root/user/C.XXXXXX
	      control file

       root/user/E.XXXXXX
	      error file

SOURCE

       /sys/src/cmd/upas/q

SEE ALSO

       mail(1)

																	    QER(8)

Check Out this Related Man Page

msgctl(2) System Calls Manual msgctl(2)

Name
msgctl - message control operations

Syntax
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>

int msgctl (msqid, cmd, buf)
int msqid, cmd;
struct msqid_ds, buf;

Description
The system call provides message control operations as specified by cmd. The following cmds are available:

IPC_STAT 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

IPC_SET 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:
msg_perm.uid
msg_perm.gid
msg_perm.mode /* only low 9 bits */
msg_qbytes

This cmd can be executed only by a process that has an effective user ID that is equal to superuser or the value of either msg_perm.uid or
msg_perm.cuid in the data structure associated with msqid. Only the superuser can raise the value of msg_qbytes.

IPC_RMID Remove the message queue identifier specified by msqid from the system and destroy the message queue and data structure
associated with it. This command can only be executed by a process that has an effective user ID equal to either that of the
superuser or to the value of msg_perm.uid in the data structure associated with msquid.

Return Values
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.

Diagnostics
The system call fails under the following conditions:

[EINVAL] The msqid is not a valid message queue identifier.

[EINVAL] The cmd is not a valid command.

[EACCES] The cmd is equal to IPC_STAT and read operation permission is denied to the calling process. For further information, see

[EPERM] The cmd is equal to IPC_RMID or IPC_SET and the effective user ID of the calling process is not equal to that of the supe-
ruser or to the value of msg_perm.uid in the data structure associated with msqid.

[EPERM] The cmd is equal to IPC_SET, an attempt is being made to increase to the value of msg_qbytes, and the effective user ID of
the calling process is not equal to that of superuser.

[EFAULT] The buf points to an illegal address.

Linux and UNIX Man Pages

qer(8) [plan9 man page]

Check Out this Related Man Page