702-100 Exam Dumps : Linux Professional Institute BSD Specialist

The umask command in BSD is used to set default permissions for files or directories the user creates1. The umask value is permissions to deny, taken off whatever permissions would be given by default2. The default permission values for files are 666 (rw-rw-rw-), meaning read and write for user, group, and others3. The umask value of 022 means that the permissions to deny are 022 (—w–w-), meaning write for group and others. To calculate the default permissions for newly created files, we need to subtractthe umask value from the default permission value, using bitwise AND operation4. For example:

666 - 022 = 644 rw-rw-rw- - —w–w- = rw-r–r–

Therefore, the default permissions for newly created files with a umask of 022 are 644 (rw-r–r–), meaning read and write for user, and read for group and others.

References: 1: Umask command in Linux with examples - GeeksforGeeks 2: Different permission between directory and file with ‘umask’ - Unix & Linux Stack Exchange 3: Default File Permissions (umask) - docs.oracle.com 4: What is Umask and How to Use It {Update Default Linux File Permissions} - phoenixNAP KB

The command locate.updatedb updates the database used by locate to find files. The locate command searches for files by name in a pre-built database of files and directories. The database is usually updated periodically by a cron job, but the locate.updatedb command can be used to manually update it. The command may require root privileges to run, depending on the system configuration. References:

• BSD Specialist Exam 702 Objectives, Topic 715: Basic Unix Skills, 715.4 Searching and Extracting Data from Files
• FreeBSD Handbook, Chapter 7: Finding and Installing Software, 7.2.3 Using locate(1) to Find Files Quickly

The question mark (?) is a special character in regular expressions that modifies the preceding expression to match zero or one times. For example, the regular expression colou?r matches both color and colour, but not colouur or colr. The question mark is also used to make an expression non-greedy, meaning that it will match the shortest possible string instead of the longest. For example, the regular expression <.?> matches the first pair of angle brackets in a string, while <.> matches the entire string enclosed by the outermost pair of angle brackets. References:

• Regular expression - Wikipedia, section “Basic concepts”
• How to write Regular Expressions? - GeeksforGeeks, section “Special Characters”