单选题The command echo $! will produce what output?()A  the process id of last background commandB  the exit status of the last commandC  the exit status of the last background commandD  the process id of the current shellE  the name of the command being exe

题目
单选题
The command echo $! will produce what output?()
A

 the process id of last background command

B

 the exit status of the last command

C

 the exit status of the last background command

D

 the process id of the current shell

E

 the name of the command being executed

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相似问题和答案

第1题:

Examine the data in the EMPLOYEES and DEPARTMENTS tables.EMPLOYEESLAST_NAME DEPARTMENT_ID SALARYGetz 10 3000Davis 20 1500Bill 20 2200Davis 30 5000Kochhar 5000DEPARTMENTSDEPARTMENT_ID DEPARTMENT_NAME10 Sales20 Marketing30 Accounts40 AdministrationYou want to retrieve all employees, whether or not they have matching departments in the departments table.Which query would you use?()

A. SELECT last_name, department_name FROM employees , departments(+);

B. SELECT last_name, department_name FROM employees JOIN departments(+);

C. SELECT last_name, department_name ON (e. department_ id = d. departments_id); FROM employees(+) e JOIN departments d

D. SELECT last_name, department_name FROM employees e RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id);

E. SELECT last_name, department_name FROM employees(+) , departments ON (e. department _ id = d. department _id);

F. SELECT last_name, department_name FROM employees e LEFT OUTER JOIN departments d ON (e. department _ id = d. department _id);


参考答案:F

第2题:

The administrator wants to verify the current state of the OSPF database loading process. Which show command should the administrator use?()

A. show ip ospf [process - id] interface

B. show ip ospf neighbor

C. show ip ospf [process - id]

D. show ip ospf [process - id area - id] database


参考答案:B

第3题:

Examine the structure of the EMPLOYEES table:Column name Data type RemarksEMPLOYEE_ID NUMBER NOT NULL, Primary KeyLAST_NAME VARCNAR2(30)FIRST_NAME VARCNAR2(30)JOB_ID NUMBERSAL NUMBERMGR_ID NUMBER References EMPLOYEE_ID column DEPARTMENT_ID NUMBERYou need to create an index called NAME_IDX on the first name and last name fields of the EMPLOYEES table. Which SQL statement would you use to perform this task? ()

A. CREATE INDEX NAME _IDX (first_name, last_name);

B. CREATE INDEX NAME _IDX (first_name, AND last_name)

C. CREATE INDEX NAME_IDX ON (First_name, last_name);

D. CREATE INDEX NAME_IDX ON employees (First_name, AND last_name);

E. CREATE INDEX NAME_IDX ON employees (First_name, last_name);

F. CREATE INDEX NAME_IDX FOR employees (First_name, last_name);


参考答案:E

第4题:

Click the Exhibit button and examine the data in the EMPLOYEES and DEPARTMENTS tables.You want to retrieve all employees, whether or not they have matching departments in the departments table. Which query would you use?()

  • A、SELECT last_name, department_name FROM employees NATURAL JOIN departments;
  • B、SELECT last_name, department_name FROM employees JOIN departments ;
  • C、SELECT last_name, department_name FROM employees e JOIN departments d ON (e.department_id = d.department_id);
  • D、SELECT last_name, department_name FROM employees e RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id);
  • E、SELECT last_name, department_name FROM employees FULL JOIN departments ON (e.department_id = d.department_id);
  • F、SELECT last_name, department_name FROM employees e LEFT OUTER JOIN departments d ON (e.department_id = d.department_id);

正确答案:F

第5题:

Which statement is true regarding the Archiver (ARCn) process,archived log files,and recovery? ()

  • A、A database backup, combined with archived redo log files, guarantees that all committed data can be recovered to the point of failure. 
  • B、During recovery the ARCn background process copies its redo entries identified for recovery by the control file to the data files. 
  • C、After each write to an archived log, the mandatory background process ARCn writes its log sequence number and the first and last SCN number within the log sequence to the control file. 
  • D、At database recover time, and archived redo log is uniquely identified for recovery use by its redo thread number and destination ID number retrieved from the control file.

正确答案:A

第6题:

Whichofthefollowingisthecorrectformatfor/etc/inittabentries()

A.Runlevel:Action:Identifier:Command

B.Identifier:Runlevel:Action:Command

C.Command:Action:Identifier:Process

D.Process:Runlevel:Command:Identifier


参考答案:B

第7题:

The administrator wants to verify the current state of the OSPF database loading process. Which show command should the administrator use?()

  • A、show ip ospf [process - id] interface
  • B、show ip ospf neighbor
  • C、show ip ospf [process - id]
  • D、show ip ospf [process - id area - id] database

正确答案:B

第8题:

ExhibitExamine the data in the EMPLOYEES and DEPARTMENTS tables.You want to retrieve all employees‘ last names, along with their manager‘s last names and their department names. Which query would you use?()

A. SELECT last_name, manager_id, department_name FROM employees e FULL OUTER JOIN department d ON (e.department_id = d.department_id);

B. SELECT e.last_name, m.last_name, department_name FROM employees e LEFT OUTER JOIN employees m on ( e.managaer_id = m.employee_id) LEFT OUTER JOIN department d ON (e.department_id = d.department_id);

C. SELECT e.last_name, m.last_name, department_name FROM employees e RIGT OUTER JOIN employees m on ( e.manager_id = m.employee_id) FULL OUTER JOIN department d ON (e.department_id = d.department_id);

D. SELECT e.last_name, m.last_name, department_name FROM employees e LEFT OUTER JOIN employees m on ( e.manager_id = m.employee_id) RIGT OUTER JOIN department d ON (e.department_id = d.department_id);

E. SELECT e.last_name, m.last_name, department_name FROM employees e RIGHT OUTER JOIN employees m on ( e.manager_id = m.employee_id) RIGHT OUTER JOIN departments d ON (e.department_id = d.department_id)

F. SELECT last_name, manager_id, department_name FROM employees e JOIN department d ON (e.department_id = d.department_id);


参考答案:B

第9题:

The command echo $! will produce what output?()

  • A、 the process id of last background command
  • B、 the exit status of the last command
  • C、 the exit status of the last background command
  • D、 the process id of the current shell
  • E、 the name of the command being executed

正确答案:A

第10题:

The EMPLOYEES table contains these columns: EMPLOYEE_ID NUMBER(4) LAST_NAME VARCHAR2 (25) JOB_ID VARCHAR2(10) You want to search for strings that contain 'SA_' in the JOB_ID column. Which SQL statement do you use?()

  • A、SELECT employee_id, last_name, job_id FROM employees WHERE job_id LIKE '%SA/_%' ESCAPE '/';
  • B、SELECT employee_id, last_name, job_id FROM employees WHERE job_id LIKE '%SA_';
  • C、SELECT employee_id, last_name, job_id FROM employees WHERE job_id LIKE '%SA_' ESCAPE "/";
  • D、SELECT employee_id, last_name, job_id FROM employees WHERE job_id = '%SA_';

正确答案:A

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