1. Xuan Guo Chapter 3-2 Graham Glass and King Ables, UNIX for Programmers and Users, Third Edition, Pearson Prentice Hall, 2003. CSc 3320 1

2. Xuan Guo uniq fed with a text file, output the file with adjacent identical lines collapsed to one uniq -c -number [inputfile [outputfile]] -c: causes each line to be preceded by the number of occurrences that were found -number: number fields of each line are ignored CSc 3320 2

3. Xuan Guo Happy Birthday to You! Happy Birthday Dear Tux! Happy Birthday to You! uniq uniq.dat Happy Birthday to You! Happy Birthday Dear Tux! Happy Birthday to You! CSc 3320 3

4. Xuan Guo Happy Birthday to You! Happy Birthday Dear Tux! Happy Birthday to You! uniq -c uniq.dat 2 Happy Birthday to You! 1 Happy Birthday Dear Tux! 1 Happy Birthday to You! CSc 3320 4

5. Xuan Guo Sort sorts a file in ascending or descending order based on one or more fields. Individual fields are ordered lexicographically, which means that corresponding characters are compared based on their ASCII value. CSc 3320 5

6. Xuan Guo Sort sort -tc -r [+POS1 [-POS2]] {sortField -bfMn}* {fileName}* –-tc separator is c instead of blank –-r descending instead of ascending –-b ignore leading blanks –-f ignore case –-M month sort (3 letter month abbreviation)‏ –-n numeric sort –+POS1 [-POS2] key positions start [up to end] CSc 3320 6

7. Xuan Guo Sort Examples CSc 3320 7 $ cat sort.dat John Smith 1222 20 Apr 1956 Tony Jones 1012 20 Mar 1950 John Duncan 1111 20 Jan 1966 Larry Jones 1223 20 Dec 1946 $ sort +0 -2 sort.dat John Duncan 1111 20 Jan 1966 John Smith 1222 20 Apr 1956 Larry Jones 1223 20 Dec 1946 Tony Jones 1012 20 Mar 1950

8. Xuan Guo Sort Examples CSc 3320 8 $ sort +4 -5 -M sort.dat John Duncan 1111 20 Jan 1966 Tony Jones 1012 20 Mar 1950 John Smith 1222 20 Apr 1956 Larry Jones 1223 20 Dec 1946 $ sort +4 -5 sort.dat John Smith 1222 20 Apr 1956 Larry Jones 1223 20 Dec 1946 John Duncan 1111 20 Jan 1966 Tony Jones 1012 20 Mar 1950

9. Xuan Guo Sort Examples CSc 3320 9 $ sort -k 6,6 -k 5,5 sort.dat Larry Jones 1223 20 Dec 1946 Tony Jones 1012 20 Mar 1950 John Smith 1222 20 Apr 1956 John Duncan 1111 20 Jan 1966

10. Xuan Guo Archiving tar -cfrtuvx tarFileName fileList –creates a “tape archive”-format file from the fileList –Typically, use either -c or -x, but not both! -c for Create -x for Extracts –-t option generates a table of contents –-r option unconditionally appends listed files to tar formatted file CSc 3320 10

11. Xuan Guo Archiving tar -cfrtuvx tarFileName fileList –-u option appends only files that are more recent than those already archived –-f option enables you to give a tar file name Default name is /dev/rmt0 –-v verbose If fileList contains directory, its contents are appended/extracted recursively. CSc 3320 11

12. Xuan Guo Archive Example CSc 3320 12 $ tar -cvf ch6.tar ch6 ch6/ ch6/menu.csh ch6/junk/ ch6/junk/junk.csh ch6/junk.csh ch6/menu2.csh ch6/multi.csh ch6/expr1.csh ch6/expr3.csh ch6/expr4.csh ch6/if.csh ch6/menu3.csh

13. Xuan Guo Archive Example CSc 3320 13 $ ls -l ch6.tar -rw-rw-r-- 1 raj raj 20480 Jun 26 20:08 ch6.tar $ tar -tvf ch6.tar drwxr-xr-x raj/raj 0 2007-06-03 09:57 ch6/ -rwxr-xr-x raj/raj 403 2007-06-02 14:50 ch6/menu.csh drwxr-xr-x raj/raj 0 2007-06-03 09:57 ch6/junk/ -rwxr-xr-x raj/raj 1475 2007-06-03 09:57 ch6/junk/junk.csh -rwxr-xr-x raj/raj 1475 2007-06-03 09:56 ch6/junk.csh -rw-r--r-- raj/raj 744 2007-06-02 15:59 ch6/menu2.csh -rwxr-xr-x raj/raj 445 2007-06-02 15:26 ch6/multi.csh -rwxr-xr-x raj/raj 279 2007-06-02 15:18 ch6/expr1.csh -rwxr-xr-x raj/raj 98 2007-06-02 15:20 ch6/expr3.csh -rwxr-xr-x raj/raj 262 2007-06-02 15:21 ch6/expr4.csh -rwxr-xr-x raj/raj 204 2007-06-02 15:22 ch6/if.csh -rw-r--r-- raj/raj 744 2007-06-02 16:01 ch6/menu3.csh

14. Xuan Guo Archive Example CSc 3320 14 $ rm -fr ch6 $ tar -rvf ch6.tar date.txt date.txt $ tar -tvf ch6.tar drwxr-xr-x raj/raj 0 2007-06-03 09:57 ch6/ -rwxr-xr-x raj/raj 403 2007-06-02 14:50 ch6/menu.csh drwxr-xr-x raj/raj 0 2007-06-03 09:57 ch6/junk/ -rwxr-xr-x raj/raj 1475 2007-06-03 09:57 ch6/junk/junk.csh -rwxr-xr-x raj/raj 1475 2007-06-03 09:56 ch6/junk.csh -rw-r--r-- raj/raj 744 2007-06-02 15:59 ch6/menu2.csh -rwxr-xr-x raj/raj 445 2007-06-02 15:26 ch6/multi.csh -rwxr-xr-x raj/raj 279 2007-06-02 15:18 ch6/expr1.csh -rwxr-xr-x raj/raj 98 2007-06-02 15:20 ch6/expr3.csh -rwxr-xr-x raj/raj 262 2007-06-02 15:21 ch6/expr4.csh -rwxr-xr-x raj/raj 204 2007-06-02 15:22 ch6/if.csh -rw-r--r-- raj/raj 744 2007-06-02 16:01 ch6/menu3.csh -rw-rw-r-- raj/raj 29 2007-06-21 11:06 date.txt

15. Xuan Guo Archive Example CSc 3320 15 $ tar -xvf ch6.tar ch6/ ch6/menu.csh ch6/junk/ ch6/junk/junk.csh ch6/junk.csh ch6/menu2.csh ch6/multi.csh ch6/expr1.csh ch6/expr3.csh ch6/expr4.csh ch6/if.csh ch6/menu3.csh date.txt

16. Xuan Guo Find Utility find pathList expression finds files starting at pathList finds files descending from there Allows you to perform certain actions –e.g. deleting the files CSc 3320 16

17. Xuan Guo Find Utility -name pattern true if the file name matches pattern -perm oct true if the octal description of file's permission equals oct -type ch true if the type of the file is ch (b=block, c=char..)‏ -user userId true if the owner of the file is userId -group groupId true if the group of the file is groupId CSc 3320 17

18. Xuan Guo Find Utility -atime count true if the file has been accessed within the count-th day -ctime count true if the contents of the file have been modified within the count-th day or any of its file attributes have been modified -exec command true if the exit code = 0 from executing the command. command must be terminated by \; If {} is specified as a command line argument it is replaced by the file name currently matched CSc 3320 18

19. Xuan Guo Find Utility -print prints out the name of the current file and returns true -ls displays the current file's attributes and returns true !expression negation of expression expr1 [-a] expr2 short circuit and expr1 -o expr2 short circuit or CSc 3320 19

20. Xuan Guo Find Examples $ find / -name x.c –searches for file x.c in the entire file system $ find. -mtime 14 -ls –lists files modified in the 14th day of the past $ find. -name '*.bak' -ls -exec rm {} \; –ls and then remove all files that end with.bak CSc 3320 20

21. Xuan Guo Find Examples CSc 3320 21 $ find ch6 -name ‘j*’ ch6/junk ch6/junk/junk.csh ch6/junk.csh

22. Xuan Guo Scheduling Command (cron)‏ $ crontab cronTabName $ crontab -ler [useName] –Allows you to schedule a series of jobs –Executed on a periodic basis –Uses a file with the following line format: CSc 3320 22 minute hour day month weekday command (0-59) (0-23) (1-31) (1-12) (1-7; 1=Monday) (any command)‏

23. Xuan Guo Scheduling Example CSc 3320 23 $ cat crontab.cron 0 8 * * 1 echo Happy Monday Morning * * * * * echo One Minute passed > /dev/pts/0 minute hour day month weekday command (0-59) (0-23) (1-31) (1-12) (1-7; 1=Monday) (any command)‏

24. Xuan Guo Scheduling Example CSc 3320 24 $ crontab crontab.cron $ crontab -l # DO NOT EDIT THIS FILE - edit the master and reinstall. # (crontab.cron installed on Sat Jun 26 23:33:35 2007)‏ # (Cron version -- $Id: crontab.c,v 2.13 1994/01/17 03:20:37 vixie Exp $)‏ 0 8 * * 1 echo Happy Monday Morning * * * * * echo One Minute passed > /dev/pts/0 $ crontab -r unregister crontab file

25. Xuan Guo Scheduling Command (at)‏ $ at command –allows you to schedule one-time commands/scripts $ at -csm time [date [, year]] [+increment] [-f script] –-c option : use C-shell –-s option : use Bourne shell –-m option : send mail CSc 3320 25

26. Xuan Guo Scheduling Command (at)‏ $ at -l –-l option list all entries in at queue $ atrm [jobId]+ –remove entries in at queue CSc 3320 26

27. Xuan Guo Scheduling Command (at)‏ $ at -csm time [date [, year]] [+increment] [script] –time is specified as HH or HHMM followed by an optional AM/PM –date is spelled out using first 3 letters of day and/or month –keyword now can be used in place of time sequence; today and tomorrow can be used in place of date –stated time may be augmented by an increment (number followed by minutes/hours/days/weeks/months/years)‏ CSc 3320 27

28. Xuan Guo Scheduling Example CSc 3320 28 $ cat at.csh #!/bin/csh echo at done > /dev/tty1 $ at now + 2 minutes -f at.csh $ at -l lists the job here You may program the script to reschedule itself as follows: #!/bin/csh date > /dev/tty1 at now + 2 minutes -f at.csh

29. Xuan Guo Hard Links $ ln original newLink –Creates a hard link to original file called newLink –Both labels will refer to the same file –File will be deleted only when both labels are removed –If newLink is a directory then links are made within the directory CSc 3320 29

30. Xuan Guo Hard Link Example CSc 3320 30 $ cat > one This is an example file. $ ln one two $ cat two This is an example file. $ vi two # changed “an” to “a great” $ cat two This is a great example file. $ cat one This is a great example file. $ ls -l two -rw-r--r-- 2 mweeks mweeks 31 Sep 14 03:26 two

31. Xuan Guo Soft (Symbolic) Links $ ln -s original newLink –Symbolic/soft links can be created from one file system into another file system –Hard links are restricted to one file system Use ls -lL to view link details –which file it refers to ls -l displays the contents of the symbolic link CSc 3320 31 $ ls -l lrwxrwxrwx 1 root root 23 2006-09-22 20:26 javac -> j2sdk1.4.2_05/bin/javac $ ls -lL -rwxrwxr-x 1 10016 users 66156 2004-06-04 00:32 javac $ ls -l j2sdk1.4.2_05/bin/javac -rwxrwxr-x 1 10016 users 66156 2004-06-04 00:32 j2sdk1.4.2_05/bin/javac

32. Xuan Guo In Depth Unix files consist of two parts: the data part and the filename part. The data part is associated with something called an 'inode'. The inode carries the map of where the data is, the file permissions, etc. for the data. CSc 3320 32

33. Xuan Guo In Depth The filename part carries a name and an associated inode number. More than one filename can reference the same inode number; these files are said to be 'hard linked' together. CSc 3320 33

34. Xuan Guo In Depth a 'soft link' or a 'symbolic link' is a special file type whose data part carries a path to another file. CSc 3320 34

35. Xuan Guo Substituting User $ su [-] userName –If userName is not specified, root is assumed –Need access privileges for this –Requires password $ sudo command –User can execute command as superuser –Requires password CSc 3320 35

36. Xuan Guo Compress/Uncompress gzip –$ gzip fileName (.gz)‏ –$ gunzip filename tar –$ tar –zcvf filename {filename}* CSc 3320 36

37. Xuan Guo Translate Utility (tr)‏ $ tr set1 set2 maps all characters in std. input from character set set1 to the corresponding character in set2 If length of set2 is less, the last character is repeated. CSc 3320 37

38. Xuan Guo Translate Utility (tr)‏ $ tr -cds set1 set2 –-c option causes string1 to be complemented (every character not in string1 now is in string1!)‏ –-d option causes every character in string1 to be deleted from std. input –-s option causes every repeated character in string1 to be condensed to one occurrence CSc 3320 38

39. Xuan Guo Examples of tr $ tr a-z A-Z file2 –causes lower-case to upper-case conversion $ tr -c a X file2 –causes every non-a character to be replaced by X (including newline)‏ $ tr -c a-z '\012' file2 –causes all non alphabetic characters to be replaced by ASCII 12 (newline)‏ $ tr -d a-c file2 –causes all a, b, c to be deleted from file1 CSc 3320 39

40. Xuan Guo Comparing Files What if you have two files with the same name, but different sizes? $ cmp file1 file2 offset1 offset2 –compares two files for equality –reports the first byte where there is a mismatch –if one file is a prefix of the other, EOF message is displayed CSc 3320 40

41. Xuan Guo Comparing Files cmp -ls file1 file2 offset1 offset2 Optional values offset1 and offset2 are the offsets into the files where comparison begins. –-l option displays the line number and byte offset of all mismatched bytes –-s option suppresses all output, return exit status only (0, 1, >1) CSc 3320 41

42. Xuan Guo Comparing Files $ diff -i file1 file2 –compares two files –outputs a description of their differences –-i flag ignores case –(a for add, c for change, or d for delete) CSc 3320 42