1. Chapter 10 Advanced File Processing

2. Regular Expressions A compact notation for representing patterns in strings Used by many common Linux utilities such as: – less/more – ed – vi – emacs – egrep – grep – fgrep – awk – sed – lex – perl – python

3. Table 10.1 Regular Expression Operators

4. Table 10.1 More Regular Expression Operators

5. Regular Expression Examples cat|dog matches "cat" or "dog“..at matches any three-character string ending with "at", including "hat", "cat", and "bat". [hc]at matches "hat" and "cat". [^b]atmatches all strings matched by.at except "bat". ^[hc]at matches "hat" and "cat", but only at the beginning of the string or line. [hc]at$matches "hat" and "cat", but only at the end of the string or line.

6. Regular Expression Examples (0|1)+ 1+0* a*ba*ba* [A-Za-z][A-Za-z0-9]* (yaba|daba)+doo

7. Table 10.2 Examples of Regular Expressions for vi and Their Meaning

8. Table 10.3 Some Commonly Used vi Commands Illustrating the Use of Regular Expressions

9. File Compression compress uncompress gzip gunzip gzexe zcat zmore uuencode uudecode

10. Figure 10.1 The process of uuencoding and uudecoding

11. The Sort Utility Sorts lines of ASCII text Options for: – Ascending/descending order – Case folding – Ignoring leading whitespace – Alpha/numeric – Multiple keys

12. sort - sort lines of text files Syntax sort [OPTION]... [FILE]... Options -b, --ignore-leading-blanks ignore leading blanks -d, --dictionary-order consider only blanks and alphanumeric characters -f, --ignore-case fold lower case to upper case characters -i, --ignore-nonprinting consider only printable characters -n, --numeric-sort compare according to string numerical value -r, --reverse reverse the result of comparisons Other options: -k, --key=POS1[,POS2] start a key at POS1, end it at POS2 (origin 1) -t, --field-separator=SEP use SEP instead of non-blank to blank transition

13. Sort examples File donors.dat Bay Ching 500000 China Jack Arta 250000 Indonesia Cruella Lumper 725000 Malaysia sort donors.dat Bay Ching 500000 China Cruella Lumper 725000 Malaysia Jack Arta 250000 Indonesia

14. Sort Example – by last name sort +1 donors.dat Jack Arta 250000 Indonesia Bay Ching 500000 China Cruella Lumper 725000 Malaysia

15. Sort Example – by donation amount sort +2 donors.dat Jack Arta 250000 Indonesia Bay Ching 500000 China Cruella Lumper 725000 Malaysia sort +2 -n donors.dat Jack Arta 250000 Indonesia Bay Ching 500000 China Cruella Lumper 725000 Malaysia sort +2 -n -r donors.dat Cruella Lumper 725000 Malaysia Bay Ching 500000 China Jack Arta 250000 Indonesia

16. Locating Files find whereis which

17. Find command Syntax Find directory-list expression Searches directory-list for files that match conditions in expression Can find files by name, owner, permission, size, age, links

18. Find Command Examples find ~ -name *.gif -print find / -name socket.h -print find / -size+5000000c -print find ~ -newer filetocompare

19. Searching File Contents grep egrep fgrep

20. Grep – Get Regular Expression & Print Syntax grep [options] pattern [file-list] Searches files in file-list, prints lines which match the given pattern Options to fold case, print line #’s, filenames, non- matching lines fgrep – faster but dumb egrep – slower but more powerful

21. Command History A list of the recently used commands is maintained and controlled by the variables: – HISTSIZE – HISTFILE – HISTFILESIZE

22. Table 10.4 Commonly Used Event Designators for History Expansion

23. Table 10.5 Commonly Used Event Designators for History Expansion

25. Table 10.6 Commonly Used Modifiers for History Expansion