Hoofdstuk 7 meerkeuze Flashcards

1
Q

Compression on a file works by:

Removing redundant information
Eliminating gaps within the file
Storing most of the data on removable media and just leaving a pointer
Consolidating multiple files into one
Removing the high order bit from each byte
A

Removing redundant information

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2
Q

In general, for which of the following would you want to use lossless compression?

    A log file
    A movie
    A JPEG image
    An mp3 audio file
    An encrypted email
A

A log file

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3
Q

Lossy compression:
(choose three)

Decompresses to an identical version as the original
Is often used with documents
Is often used with images
Usually results better compression than lossless
Sacrifices some quality
A

Is often used with images
Usually results better compression than lossless
Sacrifices some quality

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4
Q

You type gzip myfile.tar. What happens?
(choose two)

myfile.tar is removed
myfile.tar.gz holds a compressed version of myfile.tar
An error; you forgot to specify the file with –f
myfile.tar is unarchived into the current directory
An error; you forgot to pass the name of the output file
A

myfile. tar is removed

myfile. tar.gz holds a compressed version of myfile.tar

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5
Q

How would you obtain output similar to the following?
compressed​​ ​​​uncompressed ratio uncompressed_name
278168 1016950 72.6% tags

gunzip –t tags
file tags
gzip –l tags
A

gzip –l tags

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6
Q

Which command would you use to archive the Documents directory and compress it with bzip2 compression?

    tar –czf documents.tbz Documents
    tar –cjf Documents
    tar –fzc Documents documents.tbz
    tar –cjf documents.tbz Documents
    tar –cf Documents documents.tbz
A

tar –cjf documents.tbz Documents

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7
Q

Which flag would you pass to tar in order to have it make a new archive?

    –t
    -c
    –j
    -x
    –n
A

-c

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8
Q

Which command will show what is inside the compressed tarball with a name of foo.tar.gz?

    tar –tjf foo.tar.gz
    tar –tzf foo.tar.gz
    tar –lf foo.tar.gz
    tar –xf foo.tar.gz
    tar –tf foo.tar.gz
A

tar –tzf foo.tar.gz

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9
Q

In the command tar –cvjf foo.tbz a b c, what are a, b, and c?

File names to be added to the archive
Matching operators; anything starting with a, b, or c will be added
a is the directory that will be prepended to files; b and c are files inside it
Extra flags passed to tar
Nothing; -cvjf only expects one parameter
A

File names to be added to the archive

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10
Q

Given the command tar –cvjf homedirs.tbz /home, which of the following are true?
(choose two)

The /home directory will be restored with the contents of homedirs.tbz
Only files starting with /home will be extracted from the archive
The command will print out each filename as it is processed
Files that are present in the archive might overwrite files in /home
The output file will be compressed
A

The command will print out each filename as it is processed

The output file will be compressed

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11
Q

You archived your users’ directories into a file called backup.tar.gz. You then view the archive and see the filenames follow this convention:
home/username/somefile

    How will you extract just the files for the user called fred?
    tar –tzf /home/fred < backup.tar.gz
    tar –tjf backup.tar.gz /home/fred
    tar –xjf backup.tar.gz home/fred/
    tar –xzf backup.tar.gz home/fred/
    tar –xzf backup.tar.gz fred
A

tar –xzf backup.tar.gz home/fred/

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12
Q

Which of the following commands will create a zipfile with the contents of your Documents directory?

    zip –cf mydocs.zip Documents
    zip –c mydocs.zip Documents
    zip -r mydocs.zip Documents
    zip mydocs.zip Documents
    zip –f mydocs.zip Documents
A

zip -r mydocs.zip Documents

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13
Q

Given a file called documents.zip, how can you see what’s in it without extracting the files?

    showzip documents.zip
    zip –lf documents.zip
    zip –l documents.zip
    unzip –list documents.zip
    unzip –l documents.zip
A

unzip –l documents.zip

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14
Q

Given a file called documents.zip, how can you extract just the files under ProjectX?

    zip –x documents.zip ProjectX
    unzip documents.zip | grep ProjectX
    unzip –t documents.zip ProjectX
    unzip documents.zip ProjectX
    unzip documents.zip ProjectX/*
A

unzip documents.zip ProjectX/*

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15
Q

You try to compress a file that is already compressed. Which of the following statements is true?

The file will not be compressed any further than it already was
The compression algorithm needs to be set to the “currently compressed” mode for it to be compressed further
The file will actually be uncompressed
The file will be deleted
The file changed while you were compressing it
A

The file will not be compressed any further than it already was

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16
Q

Which of the following commands can be used to compress a file?
(choose three)

    bunzip2
    bzip2
    gzip
    cat
    zip
A

bzip2
gzip
zip

17
Q

The three main modes of tar are:
(choose three)

    Copy
    List
    Compress
    Create
    Extract
A

List
Create
Extract

18
Q

In the command tar –czf foo.tar.gz bar, what is the purpose of the f flag?

Tells tar to read from the file that follows the flag
Tells tar to print the name of each file as it is processed
Tells tar to copy only files, and not directories
Specifies extra compression is to be used
Tells tar to write to the file that follows the flag
A

Tells tar to write to the file that follows the flag

19
Q

Which two commands do the same thing?
(choose two)

    tar –czf foo.tar.gz foo
    tar –c foo | gzip > foo.tar.gz
    tar –xzf foo.tar.gz
    tar –x foo | gzip
    tar –tzf foo.tar.gz
A

tar –czf foo.tar.gz foo

tar –c foo | gzip > foo.tar.gz

20
Q

The _____ command is normally executed daily to update the database of all files that are on the system.

updatedb
search
locate
find
A

updatedb