Tom, I've written Pro/C to generically dump any table to delimited ASCII. It dynamically builds a select statement with a single column containing all the table's. The Linux Kernel Module Programming Guide was originally written for the 2.2 kernels by Ori Pomerantz. Eventually, Ori no longer had time to maintain. The book 'Java for Kids' was written by Yakov Fain, Java Champion. The goal is to help students learn to program in the most popular language in the world: Java. Sometimes you need to access operating system functionality from within an SQL statement. For example, you may want to write some information to a file. Scheduling Jobs with Oracle Scheduler. About Scheduler Objects and Their Naming. You operate Oracle Scheduler by creating and managing a set of Scheduler objects. Remote Procedure Calls (RPC) This chapter provides an overview of Remote Procedure Calls (RPC) RPC. RPC is a powerful technique for constructing. Each Scheduler object is a complete database schema object of the form . Scheduler objects follow the naming rules for database objects exactly and share the SQL namespace with other database objects. Follow SQL naming rules to name Scheduler objects in the DBMS. By default, Scheduler object names are uppercase unless they are surrounded by double quotes. For example, when creating a job, job. These naming rules are also followed in those cases where comma- delimited lists of Scheduler object names are used within the DBMS. This section introduces you to basic job tasks, and discusses the following topics: See Also. This procedure is overloaded to enable you to create different types of jobs that are based on different objects. You can create multiple jobs in a single transaction using the CREATE. You can also optionally specify a credential name, a destination or destination group name, a job class, and other attributes. As soon as you enable a job, it is automatically run by the Scheduler at its next scheduled date and time. By default, jobs are disabled when created and must be enabled with DBMS. You can also set the enabled argument of the CREATE. For example, to set the logging. The creator of a job is, therefore, not necessarily the job owner. The job owner is the user in whose schema the job is created. The NLS environment of the job, when it runs, is the existing environment at the time the job was created. Example 2. 9- 1 demonstrates creating a database job called update. The job runs as the user who created the job. The repeat. Another way to limit the number of times that a repeating job runs is to set its max. You must enable it with DBMS. Note that repeating jobs are not auto- dropped unless the job end date passes, the maximum number of runs (max. In addition to specifying the job action and job repeat interval as job attributes as shown in Example 2. This is discussed in the following sections: Creating Jobs Using a Named Program. You can create a job by pointing to a named program instead of inlining its action. To create a job using a named program, you specify the value for program. The following PL/SQL block is an example of a CREATE. Lightweight jobs must reference a program, and the program type must be 'PLSQL. In addition, the program must be already enabled when you create the job. To create a job using a named schedule, you specify the value for schedule. For example, the following CREATE. You do so by creating a credential object and assigning it to the credential. A job with a NULLdestination. You assign a credential to a job so that it can authenticate with an Oracle database or the operating system before running. To create a credential: Call the DBMS. A credential can be used only by a job whose owner has EXECUTE privileges on the credential or whose owner also owns the credential. Because a credential belongs to a schema like any other schema object, you use the GRANT SQL statement to grant privileges on a credential. Example 2. 9- 2 Creating a Credential. DBMS. Credential passwords are stored obfuscated and are not displayed in the *. You designate the locations where a job runs by specifying either a single destination or a destination group in the destination. If you leave the destination. Use database destinations to specify locations where remote database jobs run. You do not need object privileges to use a destination created by another user. To create an external destination: Note. There is no DBMS. You create an external destination implicitly by registering a remote agent. This creates an external destination that references the local host. The external destination name is automatically set to the agent name. To verify that the external destination was created, query the views DBA. This designates the remote host that the database destination points to. You also specify a net service name or complete connect descriptor that identifies the database instance being connected to. If you specify a net service name, it must be resolved by the local tnsnames. If you do not specify a database instance, the remote Scheduler agent connects to its default database, which is specified in the agent configuration file. To create a database destination, you must have the CREATE JOB system privilege. To create a database destination in a schema other than your own, you must have the CREATE ANY JOB privilege. Example 2. 9- 3 Creating a Database Destination. The following example creates a database destination named DBHOST1. For this example, assume the following: You installed a Scheduler agent on the remote host dbhost. You did not modify the agent configuration file to set the agent name. Therefore the agent name and the external destination name default to DBHOST1. You used Net Configuration Assistant on the local host to create a connect descriptor in tnsnames. Oracle Database instance named orcldw, which resides on the remote host dbhost. You assigned a net service name (alias) of ORCLDW to this connect descriptor. You can specify group members (destinations) when you create the group, or you can add group members at a later time. To create a destination group: Call the DBMS. For remote database jobs, you must specify a group of type 'DB. If omitted, the job using this destination member uses its default credential. You can include another group of the same type as a member of a destination group. Upon group creation, the Scheduler expands the included group into its members. If you want the local host to be one of many destinations on which a job runs, you can include the keyword LOCAL as a group member for either type of destination group. LOCAL can be preceded by a credential only in an external destination group. A group is owned by the user who creates it. You must have the CREATEJOB system privilege to create a group in your own schema, and the CREATEANYJOB system privilege to create a group in another schema. You can grant object privileges on a group to other users by granting SELECT on the group. Example 2. 9- 4 Creating a Database Destination Group. This example creates a database destination group. Because some members do not include a credential, a job using this destination group must have default credentials. A credential must also be specified so the job can authenticate with the remote database. The example uses the credential created in Example 2. Example 2. 9- 3. A typical reason to do this is to run a database maintenance job on all of the databases that you administer. Rather than create the job on each database, you create the job once and designate multiple destinations for the job. From the database where you created the job (the local database), you can monitor the state and results of all instances of the job at all locations. To create a multiple- destination job: Call the DBMS. Because this is a system administration job, it uses a credential with system administrator privileges. The following code example sets the end date job argument, which is the second argument expected by the reporting program. DBMS. You can set argument values using either the argument name or the argument position. To use argument name, the job must reference a named program object, and the argument must have been assigned a name in the program object. If a program is inlined, only setting by position is supported. Arguments are not supported for jobs of type 'PLSQL. This procedure can be used for both regular and ANYDATA arguments. SET. Therefore, argument values that are not of SQL type, such as booleans, are not supported as program or job arguments. Setting Additional Job Attributes. After creating a job, you can set additional job attributes or change attribute values by using the SET. You can also set job attributes with Enterprise Manager. Although many job attributes can be set with the call to CREATE. It contains three steps. Step 1—Create the Script That Invokes RMANCreate a shell script that calls an RMAN script to perform a cold backup. The shell script is located in $ORACLE. It must be executable by the user who installed Oracle Database (typically the user oracle). The script is located in $ORACLE. Example 2. 9- 6 demonstrates how to use this procedure to create multiple jobs in a single transaction. Example 2. 9- 6 Creating Multiple Jobs in a Single Transaction. The job runs cmd. For local external jobs, stdout output is stored in a log file in ORACLE. It is not necessary to supply this path to GET. After running, the job is dropped. You do so using the SET. If there is a running instance of the job when the change is made, it is not affected by the call. The change is only seen in future runs of the job. In general, you should not alter a job that was automatically created for you by the database. Jobs that were created by the database have the column SYSTEM set to TRUE in job views. The attributes of a job are available in the *. However, these changes do not take effect until the next scheduled run of the job. See Oracle Database PL/SQL Packages and Types Reference for detailed information about the SET. The job runs as the user who is the job owner, or in the case of a local external job with a credential, as the user named in the credential. To find out whether the job succeeded, you must query the job views (*. To find out whether the job succeeded, you must query the job views or the job log. By calling DBMS. You can run the job asynchronously, which is similar to the previous two methods of running a job, or synchronously, in which the job runs in the session that called RUN. Provided that job is enabled, the Scheduler runs it automatically. Stopping Jobs. You stop one or more running jobs using the STOP. A job destination ID is a number, assigned by the Scheduler, that represents a unique combination of a job, a credential, and a destination. Unix System Calls. System calls are functions that a programmer can call to perform the. There are several online books that describe. C. System calls can be roughly grouped into five major categories(System. Wikipedia): process control, file management, device management. We will reproduce Wikipedia classification with some modifications. Process Control (see separate page. Process control ). They are organized as follows: 1. Commands This section provides information about user- level. UNIX System Calls This section gives information about. UNIX operating system, such. These. are often accessed by C programmers. Libraries This section contains the library routines that. An example library that comes with each system. Like the system call section, this is relevant to programmers. File Formats This section contains information on the file. This is useful. for system administrators. File Formats This section contains information on various. For example, a manual page exists here to display. ASCII character set (ascii). Games This section usually contains directions for games. Device Drivers This section contains information on UNIX. These are usually pertinent to. System Maintenance This section contains information on. Section 2 can be very useful as a reference. When you invoke the. The default. pager for most UNIX systems is the more command. You can, however. PAGER environment variable. It usually. can get you some useful links to the information for a particular call. Some of them involve access to data that users must not be permitted. System calls for low level file I/Ostat. They are used in the same way and. To obtain information about a system call or library routine, how to. Here is an excerpt from. Rochkind's book that. The subject of this book is UNIX system calls, which form the interface. UNIX kernel and the user programs that run on top of it. System calls are the only way to access kernel facilities. System calls define what UNIX is. Everything else - - subroutines. While the novelty of many. UNIX's. renown, they could as well have been programmed on any modern operating. When one describes UNIX as elegant. When I first. started programming UNIX, in 1. UNIX. - - and its programmer's manual - - was only a fraction of its present. There weren't any programming examples in the manual. Even Dennis Ritchie and Ken Thompson, the inventors of. UNIX, took time out to help me. Today's aspiring UNIX programmers have a tougher challenge than I. UNIX is now so widely dispersed that an expert is unlikely to be. Most computers running UNIX are licensed for the object code. It's now full of grotesque paragraphs. If the set- user- ID mode bit of the new process file is set. ID of the new process. ID of the new process file. Similarly, if the set- group- ID. ID. of the new process is set to the group ID of the new process file. As an old- timer I understood what this meant when I first saw it. And until now, there's. This book's goal is to allow any experienced programmer. UNIX system calls as easily as I did, and then to use them. It's packed with examples - - over 3. C code. Instead of just tactics (how the system calls are used), I've. And there's. lots of informal advice as well, based on my experiences programming. UNIX over the past dozen years. Flavors of Unix. The number of different flavors of Unix is amazing, and what is worse. One. of the goals in writing Unix programs is to make them as portable as possible. Unix; obviously this isn't possible. The number of system calls has quadrupled, more or less, depending on. The second edition includes about 3. Historically there were several variant of Unix calls: Version 7, the last release from the Bell Laboratories research. Although now an antique, this version is the ancestor. Unix flavors now in use. It's probably the classic version. Unix. System V, from AT& T. This is based on Version 7, but with. System V is the standard Unix, because. AT& T own the Unix trademark. Xenix, for example, used this version. Based on System V, this also has lots of new. BSD4. 3 and System V are the two most popular flavors of Unix. System V Release 4, from AT& T. They realized that BSD4. Unix were stealing their market, so they grabbed. Unix, and added them. System V. So System V Release 4 is very sophisticated, but also very. This is the most current API and utilities standard. With wide support from many. Unix developers, it is expected that most of Unix flavors will. POSIX compatible, and that will make Unix programs much more. Mostly POSIX but with some strange perversions. There is no difference. For example, the read. The implementation of the subroutine read varies with the UNIX implementation. Nowadays, it's safe to assume that system calls are simply C subroutines. So avoiding excessive system. In the read example above, the number. To indicate an error, a system call returns a. Therefore, our. read example should have been coded something like this: if ((amt= read(fd, buf, numbytes)) == - 1). There are lots of reasons why a system call that returns - 1. The global integer errno contains a code that. These error codes are defined at the beginning of. UNIX manual . The library routine perror takes as its argument a string, and. So, a way of handling the error above that gives. This shows you what type of value the system call returns. As an example, here is part of the man. SYNOPSIS #include < unistd. DESCRIPTIONRead() attempts to read nbytes of data from the object. RETURN VALUESIf successful, the number of bytes actually read is returned. Upon reading. end- of- file, zero is returned. Otherwise, a - 1 is returned and the global. The first part shows what header files you need to include. Then the. declaration of the system call is given. The names of the arguments given in the man pages need not be the same. For example, you could use the read() function. Every process but one has a. The exception is process 0, which is created and used by the kernel. A process's system data also records its parent- process- ID, the process- ID. If a process is orphaned because its parent has terminated. ID is changed to 1. This is the process- ID of the initialization. Sometimes programmers choose to implement a subsystem as a group of related. For example, a complex database. I/O. The UNIX kernel allows these related processes. One of the group members is the group leader. Each member of the. ID as its process- group- ID. The kernel. provides a system call to send a signal to each member of a designated process. Typically, this would be used to terminate the entire group as a. Any process can resign from its process group, become a leader of its. ID the same as its own process- ID. Hence, a single. user could be running, say, 1. A process group can have a control terminal, which is the first terminal. Normally, the control terminal for a. When a new. process group is formed, the processes in the new group no longer have a. The terminal device driver sends interrupt, quit, and hangup signals. Unless precautions are taken, hanging up a terminal, for example. To prevent this, a process can. This feature makes hard- wired terminals. Thus, when. a user logs off (terminating the shell, which is normally the process group. In summary, there are three process- IDs associated with each process. ID Positive integer that uniquely identifies this. Unix Permissions. A user- ID is a positive integer that is associated with a user's. When a user logs. ID the user- ID of the first process. Processes descended from the shell inherit this. ID. Users are also organized into groups (not to be confused with process. IDs too, called group- IDs. A user's login group- ID. ID of his or her login. Groups are defined in the group file ( /etc/group). While logged. in, a user can change to another group of which he or she is a member; this. ID of the process that handles the request (normally the. These two IDs are called the real user- ID and the real group- ID. Two other IDs are also associated with each process: the effective. ID and the effective group- ID. These IDs are normally the. IDs, but they can be different, as we shall. For now, we'll assume the real and effective IDs are the same. One indicates the. Each file (ordinary, directory, or special) has, in its i- node, an owner. ID and an owner group- ID. The i- node also contains three sets of three. Each set has one bit for read permission. A bit. is 1 if the permission is granted and 0 if not. There is a set for the owner. Here are the bit assignments. Permission bits are frequently specified using an octal number. For example. octal 7. The ls. command would show this combination of permissions as rwxrwxr- x. The permission system determines whether a given process can perform. For ordinary. files the meaning of the actions is obvious. For directories the meaning. What, if anything, that. Execute permission on. The permission system determines whether permission will be granted. If the effective user- ID is zero, permission is instantly granted. If the process's effective user- ID and the file's user- ID match. If neither the user- IDs nor group- IDs match, then the process is. Occasionally we want a user to temporarily take on the privileges of. For example, when we execute the passwd command to. ID to be that of. This is done by making. ID. bit. Executing a program with this bit on changes the effective user- ID. Since it's the effective. ID that determines permissions, this allows a. The set- group- ID. Since both user- IDs (real and effective) are inherited from parent process. ID feature to run with. ID for a very long time. System Calls to Get IDs. Here are the system calls to get the IDs mentioned above: int getuid() /* Get the real user- ID */. Returns the ID */. Get the real group- ID */. Returns the ID */. Get the effective user- ID */. Returns the ID */. Get the effective group- ID */. Returns the ID */. Get the process- ID */. Returns the ID */. Get the parent process- ID */. Returns the ID */. Get the process- group- ID */. Returns the ID */.
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