Selected 102-500 LPIC Level 1 Questions Answers

The correct syntax for selecting specific columns from a table in SQL is to use the SELECT keyword followed by a comma-separated list of column names and then the FROM keyword followed by the table name. Therefore, the only option that follows this syntax is C. SELECT name, address FROM contacts; The other options are incorrect because they either use parentheses around the column names, which are not needed, or they omit the comma between the column names, which causes a syntax error. References: https://www.sqltutorial.org/sql-select/

https://www.w3schools.com/mysql/mysql_select.asp

The correct crontab entry for executing myscript at 30 minutes past every hour on Sundays is D. 30 0-23 * * 0 myscript. This is because the crontab format consists of six fields: minute, hour, day of month, month, day of week, and command. The values for each field can be:

A single number, such as 5 or 10.

A range of numbers, such as 1-5 or 10-15.

A list of numbers separated by commas, such as 1,3,5 or 10,12,14.

An asterisk (*), which means all possible values for that field.

A step value, which means every nth value for that field, such as */5 or 10-20/2.

The day of week field can be either a number from 0 to 6, where 0 and 7 are Sunday, or a three-letter abbreviation, such as SUN or MON. The month field can be either a number from 1 to 12, or a three-letter abbreviation, such as JAN or FEB.

In this case, the crontab entry D. 30 0-23 * * 0 myscript means:

30: Execute the command at the 30th minute of every hour.

0-23: Execute the command for every hour from 0 (midnight) to 23 (11 PM).

*: Execute the command for every day of the month, regardless of the month.

*: Execute the command for every month, regardless of the year.

0: Execute the command only on Sundays.

The other options are either incorrect or do not match the requirement. For example, option A. 0 * * * 30 myscript means:

0: Execute the command at the 0th minute of every hour.

*: Execute the command for every hour of the day.

*: Execute the command for every day of the month, regardless of the month.

*: Execute the command for every month, regardless of the year.

30: Execute the command only on the 30th day of the week, which is invalid.

References:

Crontab Explained in Linux [With Examples]

‘crontab’ in Linux with Examples - GeeksforGeeks

Crontab Syntax on Linux + Useful Examples - Hostinger

The command userdel --force --remove bob is used to delete the user account named bob and all its associated files. The --force option forces the removal of the user account, even if the user is still logged in. The --remove option forces userdel to remove the user’s home directory and mail spool, even if another user uses the same home directory or if the mail spool is not owned by the specified user12. Therefore, options A and B are true regarding this command.

The other options are not true because:

Option C is false because the locate database is not updated by the userdel command. The locate database is updated by the updatedb command, which is usually run by cron as a scheduled job3.

Option D is false because the userdel command does not remove all files owned by bob from all mounted filesystems. The userdel command only removes the user’s home directory and mail spool, and it does not search for and delete the user files located in other file systems. You have to search for and delete the files manually1.

Option E is false because the userdel command does not delete the group with the same name as the user, unless the USERGROUPS_ENAB parameter is set to yes in the /etc/login.defs file and the group has no other members14.

References:

How to Delete/Remove Users in Linux (userdel Command) | Linuxize

userdel(8) — Linux manual page

updatedb(8) — Linux manual page

Understanding the /etc/login.defs File | Linuxize

The chage command can change the following parameters related to user password expiry and aging:

The last password change date (-d or --lastday option)

The password expiry date (-E or --expiredate option)

The minimum number of days between password changes (-m or --mindays option)

The maximum number of days during which a password is valid (-M or --maxdays option)

The number of days of warning before password expires (-W or --warndays option)

The chage command cannot change the number of days of inactivity after a password has expired before the account is locked. This parameter is controlled by the -I or --inactive option of the usermod command, which modifies the user account information. The chage command only displays the current value of this parameter, but does not allow changing it. References:

chage command in Linux with examples - GeeksforGeeks

10 chage command examples in Linux [Cheat Sheet] - GoLinuxCloud

How to Use the Chage Command in Linux – TecAdmin

How to Manage User Password Expiration and Aging in Linux - Tecmint