Unix File Organization and Basic Commands

1. File Basics

2. Outline • Unix File Organization • Basic Commands • Permission • Wildcard – Filename Expansion Csc352-Summer03, Stanley Yao

3. / usr bin dev home tmp include lib man mike joe cs352 music memo hw1.c Legend A dir A file Unix File Organization • A tree of folders and files • Directory and subdirectory • Parent and children • Root (only one) • Standard directories • Home directory • Working directory: cwd • Initial cwd for a process • Initial cwd for a shell • pwd command Csc352-Summer03, Stanley Yao

4. File Types • Normal file: executables, text files, C source files, spreadsheets, etc. • Directory: actually is a file containing a list of (file name, file location) pairs • . • .. • Device file: /dev/tty • Link: • Hard Link • Symbolic link (soft link) Csc352-Summer03, Stanley Yao

5. Pathname • A pathname identifies a particular file or directory uniquely • Absolute pathname • Relative pathname • Current Working directory • pwd Chaniging directory • cd • cd ~alon/352/demo • cd .. (moving up one directory) Csc352-Summer03, Stanley Yao

6. Outline • Unix File Organization • Basic Commands • Permission • Wildcard – Filename Expansion Csc352-Summer03, Stanley Yao

7. ls – List Files • ls • –a (show hidden files) • –l (long format) • –F (add one of the following at the end of each file name) • / - Directory • * - Executable • @ - Symbolic link • etc. Csc352-Summer03, Stanley Yao

8. Directory Related Commands • cd • pwd • mkdir • rmdir • Must be empty • rm –rf dir_name Csc352-Summer03, Stanley Yao

9. View Text Files • cat • cat mytext1 mytext2 mytext3 … • -n, -b • more • ENTER, SPACE • q • less: a more powerful “more” • ENTER, y • d, u • SPACE, b • q Csc352-Summer03, Stanley Yao

10. View Text Files (cont.) • head • -number • Multiple files are separated with “==>filenames<==” • tail • +: start relative to the beginning • -: start relative to the end • -f: follow Csc352-Summer03, Stanley Yao

11. Edit Text Files • emacs • Programming helper mode: C, HTML, TeX, Hex • Working environment: compile, email, Unix shell, time management, etc. • xemacs: version of emacs on X-win • vi • Two modes: edit & command • pico - the easiest to use. Csc352-Summer03, Stanley Yao

12. Copy, Move, Rename and Delete • cp source_file target_file • -r • -f • mv source_file target_file • Move directory & files • Rename directory & files • rm file_list • -r, -f same as in cp Csc352-Summer03, Stanley Yao

13. Legend A dir A file Before Talking About Links / usr bin dev home tmp lib man mike joe include Directory only consists of (filename, location) pairs. Where are filesactually stored? cs352 music memo hw1.c ActualData ofa File … Csc352-Summer03, Stanley Yao

14. Link • Hard link • ln oldfile newlink • ln file(s) directory • Must be within the same file system • Can’t create links for a directory • Symbolic link • ln –s source mylink • Can be across file systems (e.g. NFS) • Can create links for a directory • Like the shortcut in Microsoft Windows Csc352-Summer03, Stanley Yao

15. Search for strings in files • grep 352 tmp.dat search for the string 352 in the file tmp.dat grep –i hello *.dat would find “hello, HeLlo” in all files ending by .dat (e.g. file1.dat) Csc352-Summer03, Stanley Yao

16. Find Files • find path [expression] • Recursively descends the directory hierarchy seeking files that match the expression(s) • -name pattern • -size [+/-]n[c] (512 bytes/block) • -atime [+/-]n and -ctime [+/-]n • -prune • -exec • !, -o, -a, () Csc352-Summer03, Stanley Yao

17. Outline • Unix File Organization • Basic Commands • Permission • Wildcard – Filename Expansion Csc352-Summer03, Stanley Yao

18. File Permission • Owner, Group & Others • “rwx” for files • “rwx” for directories • To access a file, you must have permission to access all the directories in the pathname. Csc352-Summer03, Stanley Yao

19. File Permission (cont.) • Change permission: chmod • Absolutely: chmod og=rx * • Incrementally chmod +x a.out • -R • Change ownership: • chown • chgrp • -R Csc352-Summer03, Stanley Yao

20. Outline • Unix File Organization • Basic Commands • Permission • Wildcard – Filename Expansion Csc352-Summer03, Stanley Yao

21. Wildcard – Filename Expansion • Specify a group of files at one time by a pattern as a pathname • The shell replaces the pattern with all matching pathnames before executing the command. • Example: • ls sub* • ls sub?.c Csc352-Summer03, Stanley Yao

22. Wildcards & Abbreviations • ?: any single character • [list]: any character in the list • [lower-upper]: any character in the range between lower and upper (inclusive) • ls a?[c-z]?.c • *: any pattern (including null) • ~: home directory Csc352-Summer03, Stanley Yao

23. Some Issues with Wildcard • Hidden files and directories • .login, .logout • ls .l* • Report error when no matching • When requiring a single name, can’t use wildcard • cd ja* • Ambiguity • cp invoices bus* • Use “echo” to make it clear Csc352-Summer03, Stanley Yao

24. Script files • Can create a file containing a list of shall commands (say kuku.1) • To execute the kuku.1 , do either • sourcekuku.1 • Or • chmod +x kuku.1 • kuku.1 Csc352-Summer03, Stanley Yao

25. Acknowledgement • Stanley Yao • John H. Hartman, Classnotes for Csc352-Spring03, CS Dept., University of Arizona, 2003 • Gail Anderson, Paul Anderson, The Unix C Shell Field Guide, Prentice Hall, 1986 Csc352-Summer03, Stanley Yao