Linux Essentials 2.0 Chapter 9 Exam Answers

L xE er 9 E x e Liinu ux Esssen ent ntiia a alllss 2 2..0 ha aptte er Exa Ex xam xa am mA Ans ns ssw w wer we ers errs sse .0 Ch n 1. Co rre e le w by Com omp mpres ess ss ssi si sio ion io on on off a ffiiille wor ork rks k kss b by: y: wo • • • • • Eliminating gaps within the file Consolidating multiple files into one Removing redundant information Storing most of the data on removable media and just leaving a pointer Removing the high order bit from each byte 22 or w h ho lowin u yyo o 2. In n ge gener e erral al,l, for wh hic icch th he e ffo ollowi in ing woul uld ld d you ou u want ntt tto ou use se a of tthe g wo lo sssi los oss ssl sle le le esssss comp mpr mp pre rre ess sio ion io on? n? • • • • • An mp3 audio file An encrypted email A JPEG image A log file A movie 33 Lo co 3. Los o ossssy y ccom omp mpr pre res re essi sio ion on on: n: (c (ch ch cho hoo oose se e th thr hre ree e ee e)) • • • • • Usually results better compression than lossless Is often used with images Is often used with documents Decompresses to an identical version as the original Sacrifices some quality 44 4. Yo You type pe gzip myfile.tar. W Wha hatt ha ppe pen ens? s? Wh hap app p p (c hoos ttwo (cho ch hoo ose se tw w wo o)) • • • • • myfile.tar is unarchived into the current directory An error; you forgot to pass the name of the output file myfile.tar.gz holds a compressed version of myfile.tar An error; you forgot to specify the file with -f myfile.tar is removed 5. Ho wo Ho ow ww woul uld ld dy you yo ou uo obt bta tai ta ain n ou out outp uttpu putt sim imi mil ilar ar to o tthe he he ffoll follo low o ow owi wi win ing ng? g? ob 6. compressed uncompressed ratio uncompressed_name 7. 278168 1016950 • gzip –l tags • gunzip –t tags • file tags 72.6% tags 88 m woul ecto 8. Wh Whi hic h cco omm om mma m ma an and n nd d wou ou uld ld d yyo you ou us use e tto oa ar arc rch rcchi ch hiv ive ve e tthe th he Documents di diirrrec re ect cto iich cch o an com wiith bzip2 co and comp mp pre prrres e essss it w wit com om omp mp mpr pr pre re res es ess ssi sio siion io on on? n? • • • • • tar –fzc Documents documents.tbz tar –cf Documents documents.tbz tar –cjf Documents tar –cjf documents.tbz Documents tar –czf documents.tbz orrry 99 wo p hav 9. Wh Whic hiiich h ffla lag lag gw wou ou oul ul uld ld dy you yo ou u pa pass sss tto tar in no ord rde der err tto oh ave ve e it it ma mak ake ke ean ne new ew or ar arc rch chi hiv ive ve? e? • • • • • -t -c -n -x -j 111 0 Wh h com co n dw wiiilll ll sho w wh in e 1 10 0.. Whic ich omm mma m ma a an nd h ho ow wha hat at is ins nsi ssiid ide the e co com om m rres re ess sse ssse sed ed de th tarball with a name o off foo.tar.gz? • • • tar –tjf foo.tar.gz tar –lf foo.tar.gz tar –tf foo.tar.gz • • 11. • • • • • tar –xf foo.tar.gz tar –tzf foo.tar.gz In the command tar -cvjf foo.tbz a b c, w what hat are a, b, and c? Nothing; -cvjf only expects one parameter File names to be added to the archive a is the directory that will be prepended to files; b and c are files inside it Matching operators; anything starting with a, b, or c will be added Extra flags passed to tar 12. Given the command tar –cvjf homedirs.tbz /home, which of the following are true? (choose two) • • • • • Only files starting with /home will be extracted from the archive The command will print out each filename as it is processed The /home directory will be restored with the contents of homedirs.tbz Files that are present in the archive might overwrite files in /home The output file will be compressed 13. You archived your users’ directories int into o a file called backup.tar.gz. You then vie view w the archive and see the filenames follow this convention: home/username/somefile How will you extract just the files for the u user ser called fred? • • • • • tar –xzf backup.tar.gz home/fred/ tar –tjf backup.tar.gz /home/fred tar –xjf backup.tar.gz home/fred/ tar –xzf backup.tar.gz fred tar –tzf /home/fred < backup.tar.gz 14. Which of the following commands will create a zipfile with the contents of your Documents directory? • • • • • zip –f mydocs.zip Documents zip -r mydocs.zip Documents zip –c mydocs.zip Documents zip mydocs.zip Documents zip -cf mydocs.zip Documents 15. Given a fi file le called documents.zip, how can you see what’s in it without extracting the files? • • • • • zip -lf documents.zip unzip -l documents.zip unzip –list documents.zip zip -l documents.zip showzip documents.zip 16. Given a fi file le called documents.zip, how can you extract just the files under ProjectX? • • • • • unzip documents.zip ProjectX/* unzip documents.zip | grep ProjectX unzip documents.zip ProjectX zip -x documents.zip ProjectX unzip -t documents.zip ProjectX 17. You try to compress a fil file e 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 changed while you were compressing it • The file will be deleted • The file will actually be uncompressed • • 18. Which of the following commands can be used tto o compress a file? (choose three) • • • • • bunzip2 cat zip bzip2 gzip 19. The three main mode modess of tar are: (choose three) • • • • • List Create Compress Copy Extract 20. In the command tar -czf foo.tar.gz bar, w what hat iiss the purpose of the f flag? • • • • • 21. Tells tar to copy only files, and not directories Tells tar to read from the file that follows the flag Tells tar to write to the file that follows the flag Tells tar to print the name of each file as it is processed Specifies extra compression is to be used Which two commands do the same thing? (choose two) • • • • • tar -czf foo.tar.gz foo tar -tzf foo.tar.gz tar -c foo | gzip > foo.tar.gz tar -x foo | gzip tar -xzf foo.tar.gz 22. Which two programs use th the e LempelLempel-Ziv-Markov Ziv-Markov chain algorithm? (choose two) • • • • • xz lossless lossy bzip gzip 23. By default, the zip command replace replacess uncompressed files with compressed files. True or False? • • True False