Which of these is NOT a real Linux package manager?

Which of these is NOT a real Linux package manager?

• PETget
• Tuxbrew
• Conary
• Pacman 

EXPLANATION

Linux package managers are a dime a dozen and have lots of crazy names, like Pacman, PETget, and Conary.

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For files in Unix and Linux, "atime" means most recent access time. What does "ctime" mean?

For files in Unix and Linux, "atime" means most recent access time. What does "ctime" mean?

• the time that file was most recently copied
• the file's data change time
• the file's status change time
• the file's creation time 

EXPLANATION

atime is access time, or when the file was last read.
mtime is modification time, or when the file's data was last modified.
ctime is change time, or when the files status (metadata) was last changed.  Metadata, data about the file as opposed to data in the file, is held in the file's inode.
Unix jargon for "the time a file's status last changed". Change time and creation time (ctime)Unix and Windows file systems interpret 'ctime' differently:Unix systems maintain the historical interpretation of ctime as being the time when certain file metadata, not its contents, were last changed, such as the file's permissions or owner (e.g. 'This file's metadata was changed on 05/05/02 12:15pm').    Windows systems use ctime to mean 'creation time'[citation needed] (also called 'birth time') (e.g. 'This file was created on 05/05/02 12:15pm').

Sources:   https://en.wikipedia.org/wiki/Stat_(system_call)#ctime 

  https://en.wikipedia.org/wiki/MAC_times

SOURCE

https://www.tldp.org/LDP/Linux-Dictionary/html/Linux-Dictionary.html

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What date/time is UNIX time calculated based off of?

What date/time is UNIX time calculated based off of?

• 00:00:00 31 December 1967
• 00:00:00 1 January 0000
• 00:00:00 1 January, 1900
• 00:00:00 1 January 1970 

 

EXPLANATION

 

Epoch time, also known as Unix time, is defined as the number of seconds that have elapsed since 00:00:00 Coordinated Universal Time (UTC), Thursday, 1 January 1970 (not counting leap seconds).

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Which Symbol denotes an ID in CSS?

Which Symbol denotes an ID in CSS?

• .
• %
• $
• #

EXPLANATION

The #id selector styles the element with the specified id.
CSS Syntax:

#id {
    css declarations;
}

http://www.htmldog.com/guides/css/intermediate/classid/

 

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Why is the Power Factor (PFC) value listed on most modern PSU units?

Why is the Power Factor (PFC) value listed on most modern PSU units?

• It indicates the level of efficiency of the PSU
• It points to the materials used in the PSU (Gold, Silver etc)
• It relates with the thermal resistance properties
• Indicates coeficient for the longevity of the PSU 

 

EXPLANATION

The Power Factor value shows the efficiency of the power unit. The power unit capabilities are usually stated as W consumed by the unit (kVA). How much of this power will be available to the loads attached to the PSU however is dictated by the its conversion capabilities summarized by the PFC value. For example, a 1000W PSU with a PFC factor of 0.9 will be able to supply a total of 900W to it's loads.

The PFC itself measures the alignment of the the voltage sinusoidal against the current sinusoidal. If they match 100% you would get a PFC of 1 and hence the perfect lossless PSU. In realty >0.95 is hardly achieved and considered very good while 0.8 could be considered as average PSU. 0.7 is considered as a bad performing PSU

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