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11 qlx02vutil

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  • 1. Unit 11Linux Utilities
  • 2. Objectives_After completing this unit, you should be able to:• Use the find and locate command to search for files• Use the cut command to list specific columns of a file• Use the grep command to search text files for patterns• Use the head and tail commands to view specific lines in a file• Use the sort command to sort the contents of a file• Use the type, which and whereis commands to find commands• Use the file command to find out the content of a file• Use the join and paste commands to combine files• Manipulate files with gzip, gunzip and zcat
  • 3. The find Command• Search one or more directory structures for files thatmeet certain specified criteria• Display the names of matching files or executecommands against those filesSyntax:$ find path expression
  • 4. Sample Directory Structureblue box bigbrown circle giantgreen phone littlesquare small
  • 5. Using find• Generally, you want to search a directory structure for fileswith certain names and list the names found.$ CD /HOME/JOE $ FIND . -NAME PHONE ./SHAPE/PHONE./PHONEOn many other UNIX systems, with find you have to tell itspecifically to print the names using -print$ FIND . -NAME PHONE -PRINT ./SHAPE/PHONE./PHONE
  • 6. Executing Commands with find•The -exec option executes a command on each of the file namesfound.$ find . -name b* -exec ls -i {} ;187787 ./color/blue187788 ./color/brown 187792 ./shape/box202083 ./size big 132754 ./blues" { } " IS A PLACEHOLDER FOR EACH FILENAME. THE BACKSLASHESCAPES THE FOLLOWING SEMICOLON.
  • 7. Interactive Command Execution•The -ok option also causes command execution but on aninteractive basis:$ find . -NAME B* -OK RM {} ;< RM .. ./COLOR/BLUE > ? Y< RM .. ./color/brown > ? y< rm .. ./SHAPE/BOX > ? Y< rm .. ./size/big > ? y< rm .. ./blues > ? y
  • 8. Additional find Optionstypesizemtimepermusernewero afd+n-nnc+x-xxonummodeuserordinary file directorylarger than n blockssmaller than n blocksequal to n charactersmodified more than x days agomodified less than x days agomodified x days agoaccess permissions match onumaccess permissions match modefinds files owned by userfile was modified more recentlythan ref.fileLogical ORLogical AND
  • 9. find Examples$ find . -perm 777./SIZE/LITTLEFile matches expr 1 and expr 2: $ find . -name S* -type f -a -size +2 >-exec ls -i{} ; 187791 ./SHAPE/SQUARE 202086 ./SIZE/SMALLFile matches expr 1 or expr 2: $find . -name big -o -name c*./COLOR./SHAPE/CIRCLE ./SIZE/BIG
  • 10. locate Commandlocate allows you to quickly find a file on thesystem, based on simple criteria$ locate passwd/USR/SHARE/MAN/MAN1/PASSWD.1.GZ/USR/SHARE/MAN/MAN5/PASSWD.5.GZ/ETC/PASSWD/USR/BIN/PASSWD• Requires that the superuser runs updatedb regularly •Most distributions run updatedb automatically •SuSEdoes not install locate/updatedb by default
  • 11. The cut Command• Pull selected columns or fields from one or more files.• Syntax:cut -f(ields) -d(elimiter) file(s) cut -c(haracters) file(s)
  • 12. cut Example (1)$ cat /etc/passwdroot:x:0:0:Big Brother:/root:/bin/bashshutdown:x:6:0:shutdown:/sbin:/sbin/shutdowntux1:x:500:500::/home/tux1:/bin/bashtux2:x:501:501::/home/tux2:/bin/bash$ cut -f1,6,7 -d: /etc/passwdroot:/root:/bin/bashshutdown:/sbin:/sbin/shutdowntux1:/home/tux1:/bin/bashtux2:/home/tux2:/bin/bash
  • 13. cut Example (2)$ psPID TTY STAT TIME COMMAND374 p0 S 0:00 -bash460 p0 R 0:00 ps$ ps cut -c-5,20-PID COMMAND374 -bash471 ps
  • 14. The grep Command• Searches one or more files or standard input for linesmatching pattern• Simple match or Regular Expression Syntaxgrep [options] pattern [filel ...]
  • 15. grep Sample Data Files• Phone 1:Allet 10300 internJudith 20500 internKees 30500 externLeo 40599 externNannie 50599 externPeter 60300 internPhone 2:Allet 1342 internJudith 2083 internKees 3139 externLeo 4200 internNannie 5200 internPeter 6342 extern
  • 16. Basic grep$ grep 20 phonelJudith 20500 intern$ grep 20 phone*phonel: Judith 20500 internphone2: Judith 2083 internphone2: Leo 4200 internphone2: Nannie 5200 intern$ grep -v Judith phone2Allet 1342 internKees 3139 externLeo 4200 internNannie 5200 internPeter 6342 extern
  • 17. grep with Regular Expressions• Patterns with metacharacters should be in single quotes ( )so that the shell will leave it alone*Valid metacharacters with grep: $ . * A [ - ] .ANY SINGLE CHARACTERZero or more occurrences of the precedingcharacter Any ONE of the characters in therange a through f Any line that starts witha Any line that ends with z[a-f]AAz$
  • 18. Regular Expression1. Display all the processes that belong to tuxlUsing grep, write commands to select the following linesfrom the phonel file:2. Select all the lines of the file (blank and non-blank)grep_phonel3. Select all the lines that contain an e and end in a 0grep_phone 1
  • 19. grep Options-v Print lines that do not match-c Print only a count of matching lines-l Print only the names of the files withmatching lines-n Number the matching lines-i Ignore the case of letters when makingcomparisons-w Do a whole word search-f <file> Read expressions from file instead ofcommand line
  • 20. Other greps• fgrep allows only fixed strings (no regular expressions)• egrep allows for multiple (alternate) patterns$ egrep ■20500|40599|50599 PHONE1Judith 20500 internLeo 40599 externNannie 50599 extern•What does the following command do?$ grep 30 phone1 | grep intern????????
  • 21. The sort Command•The sort command sorts the lines in the file specified and writesthe result to standard outputsort -t(delimiter) +field -options file$ cat animalsdog.2cat.4penguin.10$ sort animalscat.4dog.2penguin.10
  • 22. sort Examples$ sort +0.1 animalscat.4penguin.10dog.2$ sort -t. +1 animalspenguin.10dog .2cat.4$ sort -t. -n +1 animalsdog. 2cat.4penguin.10Options:-d sorts in dictionary order. Only letters, digits and spaces areconsidered in comparisons -r reverses theorder of the specified sort -n sorts numeric fields inarithmetic value
  • 23. The head and tail Commands•The head command can be used to view the first few lines ofa file or files. The command syntax is: $ head [-lines] file(s)$ HEAD -5 MYFILE $ LS -L | HEAD -12•The tail command displays the last few lines of a file or files.The command syntax is: $ tail [{-lines|+lines|-f}] file(s)$ tail -20 file$ tail +20 file$ tail -f file
  • 24. The type, which and whereis Commands•To find out what the path to a command is, use type$ type find echo find is/usr/bin/find echo is ashell builtin•To find out where the binary is located, use which$ which find echo/USR/BIN/FIND/BIN/ECHO•To locate the binary, source and manual page files of acommand, use whereis$ whereis find echofind: /usr/bin/find /usr/man/man1/find.1echo: /bin/echo /usr/man/man1/echo.1
  • 25. The file Command•With the file command, you can find out what the type of data inthe file is.$ FILE /ETC/PASSWD /BIN/LS /HOME/PETER /TMP/FAKE.JPG /ETC/PASSWD:ASCII TEXT/BIN/LS: ELF 32-BIT LSB EXECUTABLE, INTEL 80386,version 1, dynamically linked, stripped /home/peter:directory/TMP/FAKE.JPG: PDF DOCUMENT, VERSION 1.3
  • 26. The gzip, gunzip and zcat CommandsTo compress or uncompress files use gzip, gunzip or zcat$ ls -l file1-rw-rw-r-- 1 team01 team01 32031 Apr 6 23:40 file1 $gzip -v file1file1: 89.9% -- replaced with file1.gz$ ls -l file1.gz-rw-rw-r-- 1 team01 team01 3265 Apr 6 23:40 file1.gz $ zcatfile1(output is the same as the output of the cat command with theuncompressed file) $ gunzip file1 $ ls -l file1-rw-rw-r-- 1 team01 team01 32031 Apr 6 23:40 file1
  • 27. The join and paste Commandsjoin and paste combine files$ cat one a apple another b beebeast $ cat two a ape b broken $join one two a apple another apeb bee beast broken $ paste onetwo a apple another a ape b beebeast b broken
  • 28. CheckpointT/F 1. The command ps -aux | grep tux | grep netscapelists all Netscape processes of a user named tux.2. Which command would best be used to locate all files in yoursystem that begin with the string "team"?a. find / -name "Ateam"b. find / -name "team*"c. find / -name "*team*"d. find / -type f -name "team"3. Translate the following command into your native language:LS -LR | EGREP "TXT$|TAB$"| SORT -RN +4 | TAIL +4 | HEAD -5
  • 29. Unit SummaryThe following commands were considered:•The find command is used to recursively searchdirectories for files with particular characteristics•The grep command is used to select entire linescontaining a particular pattern•The head and tail commands are used to view specific linesin a file•The sort command sorts the contents of a file by the optionsspecified• Find out where you can find commands with type, where andwhereis•The gzip, zcat and gunzip commands can be used tocreate and work with compressed files